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update. UpdateSlackChannelConfiguration API Version 2021-08-20 33 AWS Support App in Slack Type: String API Reference Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^.+$ Required: No channelRoleArn The Amazon Resource Name (ARN) of an IAM role that you want to use to perform operations on AWS services. For more information, see Managing access to the Support App in the AWS Support User Guide. Type: String Length Constraints: Minimum length of 31. Maximum length of 2048. Pattern: ^arn:aws:iam::[0-9]{12}:role/(.+)$ Required: No notifyOnAddCorrespondenceToCase Whether you want to get notified when a support case has a new correspondence. Type: Boolean Required: No notifyOnCaseSeverity The case severity for a support case that you want to receive notifications. If you specify high or all, at least one of the following parameters must be true: • notifyOnAddCorrespondenceToCase • notifyOnCreateOrReopenCase • notifyOnResolveCase If you specify none, any of the following parameters that you specify in your request must be false: • notifyOnAddCorrespondenceToCase • notifyOnCreateOrReopenCase • notifyOnResolveCase Request Body API Version 2021-08-20 34 AWS Support App in Slack API Reference Note If you don't specify these parameters in your request, the Support App uses the current values by default. Type: String Valid Values: none | all | high Required: No notifyOnCreateOrReopenCase Whether you want to get notified when a support case is created or reopened. Type: Boolean Required: No notifyOnResolveCase Whether you want to get notified when a support case is resolved. Type: Boolean Required: No teamId The team ID in Slack. This ID uniquely identifies a Slack workspace, such as T012ABCDEFG. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^\S+$ Required: Yes Response Syntax HTTP/1.1 200 Content-type: application/json Response Syntax API Version 2021-08-20 35 AWS Support App in Slack API Reference { "channelId": "string", "channelName": "string", "channelRoleArn": "string", "notifyOnAddCorrespondenceToCase": boolean, "notifyOnCaseSeverity": "string", "notifyOnCreateOrReopenCase": boolean, "notifyOnResolveCase": boolean, "teamId": "string" } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. channelId The channel ID in Slack. This ID identifies a channel within a Slack workspace. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^\S+$ channelName The name of the Slack channel that you configure for the Support App. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^.+$ channelRoleArn The Amazon Resource Name (ARN) of an IAM role that you want to use to perform operations on AWS services. For more information, see Managing access to the Support App in the AWS Support User Guide. Type: String Response Elements API Version 2021-08-20 36 AWS Support App in Slack API Reference Length Constraints: Minimum length of 31. Maximum length of 2048. Pattern: ^arn:aws:iam::[0-9]{12}:role/(.+)$ notifyOnAddCorrespondenceToCase Whether you want to get notified when a support case has a new correspondence. Type: Boolean notifyOnCaseSeverity The case severity for a support case that you want to receive notifications. Type: String Valid Values: none | all | high notifyOnCreateOrReopenCase Whether you want to get notified when a support case is created or reopened. Type: Boolean notifyOnResolveCase Whether you want to get notified when a support case is resolved. Type: Boolean teamId The team ID in Slack. This ID uniquely identifies a Slack workspace, such as T012ABCDEFG. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^\S+$ Errors For information about the errors that are common to all actions, see Common Errors. AccessDeniedException You don't have sufficient permission to perform this action. Errors API Version 2021-08-20 37 AWS Support App in Slack HTTP Status Code: 403 ConflictException API Reference Your request has a conflict. For example, you might receive this error if you try the following: • Add, update, or delete a Slack channel configuration before you add a Slack workspace to your AWS account. • Add a Slack channel configuration that already exists in your AWS account. • Delete a Slack channel configuration for a live chat channel. • Delete a Slack workspace from your AWS account that has an active live chat channel. • Call the RegisterSlackWorkspaceForOrganization API from an AWS account that doesn't belong to an organization. • Call the RegisterSlackWorkspaceForOrganization API from a member account, but the management account hasn't registered that workspace yet for the organization. HTTP Status Code: 409 InternalServerException We can’t process your request right now because of a server issue. Try again later. HTTP Status Code: 500 ResourceNotFoundException The specified resource is missing or doesn't exist, such as an account alias, Slack channel configuration, or Slack workspace configuration. HTTP Status Code: 404 ValidationException Your request input doesn't meet the constraints that the Support App specifies. HTTP Status Code: 400 See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command
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but the management account hasn't registered that workspace yet for the organization. HTTP Status Code: 409 InternalServerException We can’t process your request right now because of a server issue. Try again later. HTTP Status Code: 500 ResourceNotFoundException The specified resource is missing or doesn't exist, such as an account alias, Slack channel configuration, or Slack workspace configuration. HTTP Status Code: 404 ValidationException Your request input doesn't meet the constraints that the Support App specifies. HTTP Status Code: 400 See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface See Also API Version 2021-08-20 38 API Reference AWS Support App in Slack • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2021-08-20 39 AWS Support App in Slack Data Types API Reference The AWS Support App API contains several data types that various actions use. This section describes each data type in detail. Note The order of each element in a data type structure is not guaranteed. Applications should not assume a particular order. The following data types are supported: • SlackChannelConfiguration • SlackWorkspaceConfiguration API Version 2021-08-20 40 AWS Support App in Slack API Reference SlackChannelConfiguration The configuration for a Slack channel that you added for your AWS account. Contents channelId The channel ID in Slack. This ID identifies a channel within a Slack workspace. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^\S+$ Required: Yes teamId The team ID in Slack. This ID uniquely identifies a Slack workspace, such as T012ABCDEFG. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^\S+$ Required: Yes channelName The name of the Slack channel that you configured with the Support App for your AWS account. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^.+$ Required: No channelRoleArn The Amazon Resource Name (ARN) of an IAM role that you want to use to perform operations on AWS services. For more information, see Managing access to the Support App in the AWS Support User Guide. SlackChannelConfiguration API Version 2021-08-20 41 AWS Support App in Slack Type: String API Reference Length Constraints: Minimum length of 31. Maximum length of 2048. Pattern: ^arn:aws:iam::[0-9]{12}:role/(.+)$ Required: No notifyOnAddCorrespondenceToCase Whether you want to get notified when a support case has a new correspondence. Type: Boolean Required: No notifyOnCaseSeverity The case severity for a support case that you want to receive notifications. Type: String Valid Values: none | all | high Required: No notifyOnCreateOrReopenCase Whether you want to get notified when a support case is created or reopened. Type: Boolean Required: No notifyOnResolveCase Whether you want to get notified when a support case is resolved. Type: Boolean Required: No See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: See Also API Version 2021-08-20 42 AWS Support App in Slack • AWS SDK for C++ • AWS SDK for Java V2 • AWS SDK for Ruby V3 API Reference See Also API Version 2021-08-20 43 AWS Support App in Slack API Reference SlackWorkspaceConfiguration The configuration for a Slack workspace that you added to an AWS account. Contents teamId The team ID in Slack. This ID uniquely identifies a Slack workspace, such as T012ABCDEFG. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^\S+$ Required: Yes allowOrganizationMemberAccount Whether to allow member accounts to authorize Slack workspaces. Member accounts must be part of an organization in AWS Organizations. Type: Boolean Required: No teamName The name of the Slack workspace. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Pattern: ^.+$ Required: No See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: SlackWorkspaceConfiguration API Version 2021-08-20 44 AWS Support App in Slack • AWS SDK for C++ • AWS SDK for Java V2 • AWS SDK for Ruby V3 API Reference See Also API Version 2021-08-20 45 AWS Support App in Slack API Reference Common Parameters The following list contains the parameters that all actions use for signing Signature Version 4 requests with a query string. Any action-specific parameters are listed in the topic for that action. For more information about Signature Version 4, see Signing AWS API requests in the IAM User Guide. Action The action to be performed. Type: string Required: Yes Version The API version that the request is written for, expressed in the format YYYY-MM-DD. Type: string Required: Yes X-Amz-Algorithm The hash
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for Ruby V3 API Reference See Also API Version 2021-08-20 45 AWS Support App in Slack API Reference Common Parameters The following list contains the parameters that all actions use for signing Signature Version 4 requests with a query string. Any action-specific parameters are listed in the topic for that action. For more information about Signature Version 4, see Signing AWS API requests in the IAM User Guide. Action The action to be performed. Type: string Required: Yes Version The API version that the request is written for, expressed in the format YYYY-MM-DD. Type: string Required: Yes X-Amz-Algorithm The hash algorithm that you used to create the request signature. Condition: Specify this parameter when you include authentication information in a query string instead of in the HTTP authorization header. Type: string Valid Values: AWS4-HMAC-SHA256 Required: Conditional X-Amz-Credential The credential scope value, which is a string that includes your access key, the date, the region you are targeting, the service you are requesting, and a termination string ("aws4_request"). The value is expressed in the following format: access_key/YYYYMMDD/region/service/ aws4_request. API Version 2021-08-20 46 AWS Support App in Slack API Reference For more information, see Create a signed AWS API request in the IAM User Guide. Condition: Specify this parameter when you include authentication information in a query string instead of in the HTTP authorization header. Type: string Required: Conditional X-Amz-Date The date that is used to create the signature. The format must be ISO 8601 basic format (YYYYMMDD'T'HHMMSS'Z'). For example, the following date time is a valid X-Amz-Date value: 20120325T120000Z. Condition: X-Amz-Date is optional for all requests; it can be used to override the date used for signing requests. If the Date header is specified in the ISO 8601 basic format, X-Amz-Date is not required. When X-Amz-Date is used, it always overrides the value of the Date header. For more information, see Elements of an AWS API request signature in the IAM User Guide. Type: string Required: Conditional X-Amz-Security-Token The temporary security token that was obtained through a call to AWS Security Token Service (AWS STS). For a list of services that support temporary security credentials from AWS STS, see AWS services that work with IAM in the IAM User Guide. Condition: If you're using temporary security credentials from AWS STS, you must include the security token. Type: string Required: Conditional X-Amz-Signature Specifies the hex-encoded signature that was calculated from the string to sign and the derived signing key. Condition: Specify this parameter when you include authentication information in a query string instead of in the HTTP authorization header. API Version 2021-08-20 47 AWS Support App in Slack Type: string Required: Conditional X-Amz-SignedHeaders API Reference Specifies all the HTTP headers that were included as part of the canonical request. For more information about specifying signed headers, see Create a signed AWS API request in the IAM User Guide. Condition: Specify this parameter when you include authentication information in a query string instead of in the HTTP authorization header. Type: string Required: Conditional API Version 2021-08-20 48 AWS Support App in Slack API Reference Common Errors This section lists the errors common to the API actions of all AWS services. For errors specific to an API action for this service, see the topic for that API action. AccessDeniedException You do not have sufficient access to perform this action. HTTP Status Code: 403 ExpiredTokenException The security token included in the request is expired HTTP Status Code: 403 IncompleteSignature The request signature does not conform to AWS standards. HTTP Status Code: 403 InternalFailure The request processing has failed because of an unknown error, exception or failure. HTTP Status Code: 500 MalformedHttpRequestException Problems with the request at the HTTP level, e.g. we can't decompress the body according to the decompression algorithm specified by the content-encoding. HTTP Status Code: 400 NotAuthorized You do not have permission to perform this action. HTTP Status Code: 401 OptInRequired The AWS access key ID needs a subscription for the service. API Version 2021-08-20 49 AWS Support App in Slack HTTP Status Code: 403 RequestAbortedException API Reference Convenient exception that can be used when a request is aborted before a reply is sent back (e.g. client closed connection). HTTP Status Code: 400 RequestEntityTooLargeException Problems with the request at the HTTP level. The request entity is too large. HTTP Status Code: 413 RequestExpired The request reached the service more than 15 minutes after the date stamp on the request or more than 15 minutes after the request expiration date (such as for pre-signed URLs), or the date stamp on the request is more than 15 minutes in the future. HTTP Status Code: 400 RequestTimeoutException Problems with the request at the HTTP level. Reading the Request timed out. HTTP Status Code: 408 ServiceUnavailable The request has failed due to a temporary failure of the
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RequestEntityTooLargeException Problems with the request at the HTTP level. The request entity is too large. HTTP Status Code: 413 RequestExpired The request reached the service more than 15 minutes after the date stamp on the request or more than 15 minutes after the request expiration date (such as for pre-signed URLs), or the date stamp on the request is more than 15 minutes in the future. HTTP Status Code: 400 RequestTimeoutException Problems with the request at the HTTP level. Reading the Request timed out. HTTP Status Code: 408 ServiceUnavailable The request has failed due to a temporary failure of the server. HTTP Status Code: 503 ThrottlingException The request was denied due to request throttling. HTTP Status Code: 400 UnrecognizedClientException The X.509 certificate or AWS access key ID provided does not exist in our records. HTTP Status Code: 403 API Version 2021-08-20 50 AWS Support App in Slack UnknownOperationException API Reference The action or operation requested is invalid. Verify that the action is typed correctly. HTTP Status Code: 404 ValidationError The input fails to satisfy the constraints specified by an AWS service. HTTP Status Code: 400 API Version 2021-08-20 51
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Developer Guide AWS Flow Framework for Java API Version 2021-04-28 Copyright © 2025 Amazon Web Services, Inc. and/or its affiliates. All rights reserved. AWS Flow Framework for Java Developer Guide AWS Flow Framework for Java: Developer Guide Copyright © 2025 Amazon Web Services, Inc. and/or its affiliates. All rights reserved. Amazon's trademarks and trade dress may not be used in connection with any product or service that is not Amazon's, in any manner that is likely to cause confusion among customers, or in any manner that disparages or discredits Amazon. All other trademarks not owned by Amazon are the property of their respective owners, who may or may not be affiliated with, connected to, or sponsored by Amazon. AWS Flow Framework for Java Table of Contents Developer Guide What is the AWS Flow Framework for Java? ................................................................................. 1 What's in this Guide? ................................................................................................................................... 1 Getting Started ................................................................................................................................ 3 Setting up the Framework ......................................................................................................................... 3 Add the flow framework with Maven ................................................................................................. 4 HelloWorld Application ............................................................................................................................... 4 HelloWorld Activities Implementation ................................................................................................ 5 HelloWorld Workflow Worker ............................................................................................................... 6 HelloWorld Workflow Starter ............................................................................................................... 7 HelloWorldWorkflow Application .............................................................................................................. 7 HelloWorldWorkflow Activities Worker ............................................................................................ 10 HelloWorldWorkflow Workflow Worker ........................................................................................... 12 HelloWorldWorkflow Workflow and Activities Implementation ................................................. 16 HelloWorldWorkflow Starter .............................................................................................................. 20 HelloWorldWorkflowAsync Application ................................................................................................. 25 HelloWorldWorkflowAsync Activities Implementation ................................................................. 26 HelloWorldWorkflowAsync Workflow Implementation ................................................................ 27 HelloWorldWorkflowAsync Workflow and Activities Host and Starter ...................................... 29 HelloWorldWorkflowDistributed Application ....................................................................................... 30 HelloWorldWorkflowParallel Application .............................................................................................. 33 HelloWorldWorkflowParallel Activities Worker .............................................................................. 33 HelloWorldWorkflowParallel Workflow Worker ............................................................................. 35 HelloWorldWorkflowParallel Workflow and Activities Host and Starter ................................... 36 Understanding AWS Flow Framework .......................................................................................... 37 Application Structure ................................................................................................................................ 37 Role of the Activity Worker ................................................................................................................ 39 Role of the Workflow Worker ............................................................................................................ 39 Role of the Workflow Starter ............................................................................................................. 40 How Amazon SWF Interacts with Your Application ....................................................................... 40 For More Information .......................................................................................................................... 40 Reliable Execution ...................................................................................................................................... 41 Providing Reliable Communication ................................................................................................... 41 Ensuring that Results are Not Lost ................................................................................................... 42 Handling Failed Distributed Components ........................................................................................ 42 API Version 2021-04-28 iii AWS Flow Framework for Java Developer Guide Distributed Execution ................................................................................................................................ 43 Replaying Workflows ............................................................................................................................ 43 Replay and Asynchronous Workflow Methods ............................................................................... 44 Replay and Workflow Implementation ............................................................................................ 45 Task Lists and Task Execution ................................................................................................................. 45 Scalable Applications ................................................................................................................................. 47 Data Exchange Between Activities and Workflows ............................................................................. 48 The Promise<T> Type .......................................................................................................................... 48 Data Converters and Marshaling ....................................................................................................... 50 Data Exchange Between Applications and Workflow Executions ..................................................... 50 Timeout Types ............................................................................................................................................ 51 Timeouts in Workflow and Decision Tasks ...................................................................................... 51 Timeouts in Activity Tasks .................................................................................................................. 52 Understanding Tasks ..................................................................................................................... 55 Task ............................................................................................................................................................... 55 Order of Execution ..................................................................................................................................... 56 Workflow Execution ................................................................................................................................... 57 Nondeterminism ......................................................................................................................................... 60 Programming Guide ...................................................................................................................... 61 Implementing Workflow Applications ................................................................................................... 61 Workflow and Activity Contracts ............................................................................................................ 63 Workflow and Activity Type Registration .............................................................................................. 66 Workflow Type Name and Version .................................................................................................... 67 Signal Name ........................................................................................................................................... 67 Activity Type Name and Version ....................................................................................................... 67 Default Task List ................................................................................................................................... 67 Other Registration Options ................................................................................................................ 68 Activity and Workflow Clients ................................................................................................................. 68 Workflow Clients ................................................................................................................................... 69 Activity Clients ....................................................................................................................................... 77 Scheduling Options .............................................................................................................................. 81 Dynamic Clients ..................................................................................................................................... 82 Workflow Implementation ....................................................................................................................... 84 Decision Context ................................................................................................................................... 85 Exposing Execution State .................................................................................................................... 85 Workflow Locals .................................................................................................................................... 87 API Version 2021-04-28 iv AWS Flow Framework for Java Developer Guide Activity Implementation ........................................................................................................................... 89 Manually Completing Activities ......................................................................................................... 89 Implementing Lambda Tasks ................................................................................................................... 91 About AWS Lambda ............................................................................................................................. 91 Benefits and limitations of using Lambda tasks ............................................................................ 92 Using Lambda tasks in your AWS Flow Framework for Java workflows .................................... 92 View the HelloLambda sample .......................................................................................................... 97 Running Programs Written with the AWS Flow Framework for Java .............................................. 98 WorkflowWorker .................................................................................................................................... 99 ActivityWorker ....................................................................................................................................... 99 Worker Threading Model .................................................................................................................. 100 Worker Extensibility ........................................................................................................................... 102 Execution Context .................................................................................................................................... 103 Decision Context ................................................................................................................................. 103 Activity Execution Context ............................................................................................................... 105 Child Workflow Executions .................................................................................................................... 106 Continuous Workflows ............................................................................................................................ 108 Setting task priority ................................................................................................................................ 110 Setting Task Priority for Workflows ............................................................................................... 110 Setting Task Priority for Activities .................................................................................................. 111 DataConverters ......................................................................................................................................... 112 Passing Data to Asynchronous Methods ............................................................................................. 113 Passing Collections and Maps to Asynchronous Methods ......................................................... 113 Settable<T> .......................................................................................................................................... 114 @NoWait ............................................................................................................................................... 115 Promise<Void> .................................................................................................................................... 116 AndPromise and OrPromise ............................................................................................................. 116 Testability and Dependency Injection ................................................................................................. 116 Spring Integration .............................................................................................................................. 116 JUnit Integration ................................................................................................................................. 123 Error Handling .......................................................................................................................................... 129 TryCatchFinally Semantics ................................................................................................................ 131 Cancellation ......................................................................................................................................... 132 Nested TryCatchFinally ...................................................................................................................... 137 Retry Failed Activities ............................................................................................................................. 138 Retry-Until-Success Strategy ............................................................................................................ 138 API Version 2021-04-28 v AWS Flow Framework for Java Developer Guide Exponential Retry Strategy .............................................................................................................. 141 Custom Retry Strategy ...................................................................................................................... 148 Daemon Tasks ........................................................................................................................................... 151 Replay Behavior ........................................................................................................................................ 153 Example 1: Synchronous Replay ..................................................................................................... 153 Example 2: Asynchronous Replay ................................................................................................... 155 See Also ................................................................................................................................................ 155 Best Practices ............................................................................................................................... 156 Making Changes to Decider Code ........................................................................................................ 156 The Replay Process and Code Changes ......................................................................................... 156 Example Scenario ............................................................................................................................... 157 Solutions ............................................................................................................................................... 164 Troubleshooting ........................................................................................................................... 169 Compilation errors ................................................................................................................................... 169 Unknown resource fault .........................................................................................................................
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................................................................................................................ 131 Cancellation ......................................................................................................................................... 132 Nested TryCatchFinally ...................................................................................................................... 137 Retry Failed Activities ............................................................................................................................. 138 Retry-Until-Success Strategy ............................................................................................................ 138 API Version 2021-04-28 v AWS Flow Framework for Java Developer Guide Exponential Retry Strategy .............................................................................................................. 141 Custom Retry Strategy ...................................................................................................................... 148 Daemon Tasks ........................................................................................................................................... 151 Replay Behavior ........................................................................................................................................ 153 Example 1: Synchronous Replay ..................................................................................................... 153 Example 2: Asynchronous Replay ................................................................................................... 155 See Also ................................................................................................................................................ 155 Best Practices ............................................................................................................................... 156 Making Changes to Decider Code ........................................................................................................ 156 The Replay Process and Code Changes ......................................................................................... 156 Example Scenario ............................................................................................................................... 157 Solutions ............................................................................................................................................... 164 Troubleshooting ........................................................................................................................... 169 Compilation errors ................................................................................................................................... 169 Unknown resource fault ......................................................................................................................... 169 Exceptions when calling get() on a Promise ...................................................................................... 170 Nondeterministic workflows .................................................................................................................. 170 Problems due to versioning .................................................................................................................. 171 Troubleshooting and debugging a workflow execution .................................................................. 171 Lost tasks ................................................................................................................................................... 172 Validation failure due to API parameter length constraints ........................................................... 173 Reference ...................................................................................................................................... 174 Annotations ............................................................................................................................................... 174 @Activities ............................................................................................................................................ 174 @Activity .............................................................................................................................................. 175 @ActivityRegistrationOptions .......................................................................................................... 175 @Asynchronous ................................................................................................................................... 176 @Execute .............................................................................................................................................. 177 @ExponentialRetry ............................................................................................................................. 177 @GetState ............................................................................................................................................ 178 @ManualActivityCompletion ............................................................................................................ 178 @Signal ................................................................................................................................................. 179 @SkipRegistration .............................................................................................................................. 179 @Wait and @NoWait ......................................................................................................................... 179 @Workflow .......................................................................................................................................... 179 @WorkflowRegistrationOptions ...................................................................................................... 180 API Version 2021-04-28 vi AWS Flow Framework for Java Developer Guide Exceptions .................................................................................................................................................. 182 ActivityFailureException .................................................................................................................... 182 ActivityTaskException ........................................................................................................................ 183 ActivityTaskFailedException .............................................................................................................. 183 ActivityTaskTimedOutException ...................................................................................................... 183 ChildWorkflowException ................................................................................................................... 183 ChildWorkflowFailedException ......................................................................................................... 183 ChildWorkflowTerminatedException ............................................................................................... 184 ChildWorkflowTimedOutException ................................................................................................. 184 DataConverterException .................................................................................................................... 184 DecisionException ............................................................................................................................... 184 ScheduleActivityTaskFailedException ............................................................................................. 184 SignalExternalWorkflowException .................................................................................................. 184 StartChildWorkflowFailedException ................................................................................................ 185 StartTimerFailedException ................................................................................................................ 185 TimerException .................................................................................................................................... 185 WorkflowException ............................................................................................................................. 185 Packages .................................................................................................................................................... 185 Document History ........................................................................................................................ 187 API Version 2021-04-28 vii AWS Flow Framework for Java Developer Guide What is the AWS Flow Framework for Java? With the AWS Flow Framework, you can focus on implementing your workflow logic. Behind the scenes, the framework uses the scheduling, routing, and state management capabilities of Amazon SWF to manage your workflow's execution and make it scalable, reliable, and auditable. AWS Flow Framework-based workflows are highly concurrent. The workflows can be distributed across multiple components, which can run as separate processes on separate computers and be scaled independently. The application can continue to progress if any of its components are running, making it highly fault tolerant. What's in this Guide? This guide has information about how to install, set up, and use the AWS Flow Framework to build Amazon SWF applications. Getting Started with the AWS Flow Framework for Java If you are just starting out with the AWS Flow Framework for Java, read the Getting Started with the AWS Flow Framework for Java section. It will guide you through downloading and installing the AWS Flow Framework for Java, how to set up your development environment, and lead you through a simple example of creating a workflow. Understanding AWS Flow Framework for Java Introduces basic Amazon SWF and AWS Flow Framework concepts, describing the basic structure of a AWS Flow Framework application and how data is exchanged between parts of a distributed workflow. AWS Flow Framework for Java Programming Guide This chapter provides basic programming guidance for developing workflow applications with the AWS Flow Framework for Java, including how to register activity and workflow types, implement workflow clients, create child workflows, handle errors, and more. Understanding a Task in AWS Flow Framework for Java This chapter provides a more in-depth look at the way the AWS Flow Framework for Java works, providing you with additional information about the order of execution of asynchronous workflows and a logical step-through of a standard workflow execution. What's in this Guide? API Version 2021-04-28 1 AWS Flow Framework for Java Developer Guide Troubleshooting and debugging tips for AWS Flow Framework for Java This chapter provides information about common errors that you can use to troubleshoot your workflows, or that you can use to learn to avoid common errors. AWS Flow Framework for Java Reference This chapter is a reference to the Annotations, Exceptions and Packages that the AWS Flow Framework for Java adds to the SDK for Java. What's in this Guide? API Version 2021-04-28 2 AWS Flow Framework for Java Developer Guide Getting Started with the AWS Flow Framework for Java This section introduces the AWS Flow Framework by walking you through a series of simple example applications that introduce the basic programming model and API. The example applications are based on the standard Hello World application that is used to introduce C and related programming languages. Here is a typical Java implementation of Hello World: public class HelloWorld { public static void main(String[] args) { System.out.println("Hello World!"); } } The following is a brief description of the example applications. They include complete source code so you can implement and run the applications yourself. Before starting, you should first configure your development environment and create an AWS Flow Framework for Java project, like in Setting
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simple example applications that introduce the basic programming model and API. The example applications are based on the standard Hello World application that is used to introduce C and related programming languages. Here is a typical Java implementation of Hello World: public class HelloWorld { public static void main(String[] args) { System.out.println("Hello World!"); } } The following is a brief description of the example applications. They include complete source code so you can implement and run the applications yourself. Before starting, you should first configure your development environment and create an AWS Flow Framework for Java project, like in Setting up the AWS Flow Framework for Java. • HelloWorld Application introduces workflow applications by implementing Hello World as a standard Java application, but structuring it like a workflow application. • HelloWorldWorkflow Application uses the AWS Flow Framework for Java to convert HelloWorld into an Amazon SWF workflow. • HelloWorldWorkflowAsync Application modifies HelloWorldWorkflow to use an asynchronous workflow method. • HelloWorldWorkflowDistributed Application modifies HelloWorldWorkflowAsync so that the workflow and activity workers can run on separate systems. • HelloWorldWorkflowParallel Application modifies HelloWorldWorkflow to run two activities in parallel. Setting up the AWS Flow Framework for Java The AWS Flow Framework for Java is included with the AWS SDK for Java. If you have not already set up the AWS SDK for Java, visit Getting Started in the AWS SDK for Java Developer Guide for information about installing and configuring the SDK itself. Setting up the Framework API Version 2021-04-28 3 AWS Flow Framework for Java Developer Guide Add the flow framework with Maven The Amazon SWF build tools are open source—to view or download the code or to build the tools yourself, visit the repository at https://github.com/aws/aws-swf-build-tools. Amazon provides Amazon SWF build tools in the Maven Central Repository. To set up the flow framework for Maven, add the following dependency to your project's pom.xml file: <dependency> <groupId>com.amazonaws</groupId> <artifactId>aws-swf-build-tools</artifactId> <version>2.0.0</version> </dependency> HelloWorld Application To introduce the way Amazon SWF applications are structured, we'll create a Java application that behaves like a workflow, but that runs locally in a single process. No connection to Amazon Web Services will be needed. Note The HelloWorldWorkflow example builds upon this one, connecting to Amazon SWF to handle management of the workflow. A workflow application consists of three basic components: • An activities worker supports a set of activities, each of which is a method that executes independently to perform a particular task. • A workflow worker orchestrates the activities' execution and manages data flow. It is a programmatic realization of a workflow topology, which is basically a flow chart that defines when the various activities execute, whether they execute sequentially or concurrently, and so on. • A workflow starter starts a workflow instance, called an execution, and can interact with it during execution. Add the flow framework with Maven API Version 2021-04-28 4 AWS Flow Framework for Java Developer Guide HelloWorld is implemented as three classes and two related interfaces, which are described in the following sections. Before starting, you should set up your development environment and create a new AWS Java project as described in Setting up the AWS Flow Framework for Java. The packages used for the following walkthroughs are all named helloWorld.XYZ. To use those names, set the within attribute in aop.xml as follows: ... <weaver options="-verbose"> <include within="helloWorld..*"/> </weaver> To implement HelloWorld, create a new Java package in your AWS SDK project named helloWorld.HelloWorld and add the following files: • An interface file named GreeterActivities.java • A class file named GreeterActivitiesImpl.java, which implements the activities worker. • An interface file named GreeterWorkflow.java. • A class file named GreeterWorkflowImpl.java, which implements the workflow worker. • A class file named GreeterMain.java, which implements the workflow starter. The details are discussed in the following sections and include the complete code for each component, which you can add to the appropriate file. HelloWorld Activities Implementation HelloWorld breaks the overall task of printing a "Hello World!" greeting to the console into three tasks, each of which is performed by an activity method. The activity methods are defined in the GreeterActivities interface, as follows. public interface GreeterActivities { public String getName(); public String getGreeting(String name); public void say(String what); } HelloWorld has one activity implementation, GreeterActivitiesImpl, which provides the GreeterActivities methods as shown: HelloWorld Activities Implementation API Version 2021-04-28 5 AWS Flow Framework for Java Developer Guide public class GreeterActivitiesImpl implements GreeterActivities { @Override public String getName() { return "World"; } @Override public String getGreeting(String name) { return "Hello " + name + "!"; } @Override public void say(String what) { System.out.println(what); } } Activities are independent of each other and can often be used by different workflows. For example, any workflow can use the say activity to print a string to the console. Workflows can also have multiple
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} HelloWorld has one activity implementation, GreeterActivitiesImpl, which provides the GreeterActivities methods as shown: HelloWorld Activities Implementation API Version 2021-04-28 5 AWS Flow Framework for Java Developer Guide public class GreeterActivitiesImpl implements GreeterActivities { @Override public String getName() { return "World"; } @Override public String getGreeting(String name) { return "Hello " + name + "!"; } @Override public void say(String what) { System.out.println(what); } } Activities are independent of each other and can often be used by different workflows. For example, any workflow can use the say activity to print a string to the console. Workflows can also have multiple activity implementations, each performing a different set of tasks. HelloWorld Workflow Worker To print "Hello World!" to the console, the activity tasks must execute in sequence in the correct order with the correct data. The HelloWorld workflow worker orchestrates the activities' execution based on a simple linear workflow topology, which is shown in the following figure. The three activities execute in sequence, and the data flows from one activity to the next. The HelloWorld workflow worker has a single method, the workflow's entry point, which is defined in the GreeterWorkflow interface, as follows: public interface GreeterWorkflow { public void greet(); } The GreeterWorkflowImpl class implements this interface, as follows: HelloWorld Workflow Worker API Version 2021-04-28 6 AWS Flow Framework for Java Developer Guide public class GreeterWorkflowImpl implements GreeterWorkflow{ private GreeterActivities operations = new GreeterActivitiesImpl(); public void greet() { String name = operations.getName(); String greeting = operations.getGreeting(name); operations.say(greeting); } } The greet method implements HelloWorld topology by creating an instance of GreeterActivitiesImpl, calling each activity method in the correct order, and passing the appropriate data to each method. HelloWorld Workflow Starter A workflow starter is an application that starts a workflow execution, and might also communicate with the workflow while it is executing. The GreeterMain class implements the HelloWorld workflow starter, as follows: public class GreeterMain { public static void main(String[] args) { GreeterWorkflow greeter = new GreeterWorkflowImpl(); greeter.greet(); } } GreeterMain creates an instance of GreeterWorkflowImpl and calls greet to run the workflow worker. Run GreeterMain as a Java application and you should see "Hello World!" in the console output. HelloWorldWorkflow Application Although the basic HelloWorld example is structured like a workflow, it differs from an Amazon SWF workflow in several key respects: HelloWorld Workflow Starter API Version 2021-04-28 7 AWS Flow Framework for Java Developer Guide Conventional and Amazon SWF Workflow Applications HelloWorld Amazon SWF Workflow Runs locally as a single process. Runs as multiple processes that can be distribut ed across multiple systems, including Amazon EC2 instances, private data centers, client computers, and so on. They don't even have to run the same operating system. Activities are synchronous methods, which block until they complete. Activities are represented by asynchronous methods, which return immediately and allow the workflow to perform other tasks while waiting for the activity to complete. The workflow worker interacts with an activities worker by calling the Workflow workers interact with activities workers by using HTTP requests, with Amazon SWF acting as an appropriate method. intermediary. The workflow starter interacts with workflow worker by calling the Workflow starters interact with workflow workers by using HTTP requests, with Amazon SWF acting as an appropriate method. intermediary. You could implement a distributed asynchronous workflow application from scratch, for example, by having your workflow worker interact with an activities worker directly through web services calls. However, you must then implement all the complicated code required to manage the asynchronous execution of multiple activities, handle the data flow, and so on. The AWS Flow Framework for Java and Amazon SWF take care of all those details, which allows you to focus on implementing the business logic. HelloWorldWorkflow is a modified version of HelloWorld that runs as an Amazon SWF workflow. The following figure summarizes how the two applications work. HelloWorldWorkflow Application API Version 2021-04-28 8 AWS Flow Framework for Java Developer Guide HelloWorld runs as a single process and the starter, workflow worker, and activities worker interact by using conventional method calls. With HelloWorldWorkflow, the starter, workflow worker, and activities worker are distributed components that interact through Amazon SWF by using HTTP requests. Amazon SWF manages the interaction by maintaining lists of workflow and activities tasks, which it dispatches to the respective components. This section describes how the framework works for HelloWorldWorkflow. HelloWorldWorkflow is implemented by using the AWS Flow Framework for Java API, which handles the sometimes complicated details of interacting with Amazon SWF in the background and simplifies the development process considerably. You can use the same project that you did for HelloWorld, which is already configured for AWS Flow Framework for Java applications. However, to run the application, you must set up an Amazon SWF account, as follows: • Sign up for an AWS account, if you
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lists of workflow and activities tasks, which it dispatches to the respective components. This section describes how the framework works for HelloWorldWorkflow. HelloWorldWorkflow is implemented by using the AWS Flow Framework for Java API, which handles the sometimes complicated details of interacting with Amazon SWF in the background and simplifies the development process considerably. You can use the same project that you did for HelloWorld, which is already configured for AWS Flow Framework for Java applications. However, to run the application, you must set up an Amazon SWF account, as follows: • Sign up for an AWS account, if you don't already have one, at Amazon Web Services. • Assign your account's Access ID and secret ID to the AWS_ACCESS_KEY_ID and AWS_SECRET_KEY environment variables, respectively. It's a good practice to not expose the literal key values in your code. Storing them in environment variables is a convenient way to handle the issue. • Sign up for Amazon SWF account at Amazon Simple Workflow Service. HelloWorldWorkflow Application API Version 2021-04-28 9 AWS Flow Framework for Java Developer Guide • Log into the AWS Management Console and select the Amazon SWF service. • Choose Manage Domains in the upper right corner and register a new Amazon SWF domain. A domain is a logical container for your application resources, such as workflow and activity types, and workflow executions. You can use any convenient domain name, but the walkthroughs use "helloWorldWalkthrough". To implement the HelloWorldWorkflow, create a copy of the helloWorld.HelloWorld package in your project directory and name it helloWorld.HelloWorldWorkflow. The following sections describe how to modify the original HelloWorld code to use the AWS Flow Framework for Java and run as an Amazon SWF workflow application. HelloWorldWorkflow Activities Worker HelloWorld implemented its activities worker as a single class. An AWS Flow Framework for Java activities worker has three basic components: • The activity methods—which perform the actual tasks—are defined in an interface and implemented in a related class. • An ActivityWorker class manages the interaction between the activity methods and Amazon SWF. • An activities host application registers and starts the activities worker, and handles cleanup. This section discusses the activity methods; the other two classes are discussed later. HelloWorldWorkflow defines the activities interface in GreeterActivities, as follows: import com.amazonaws.services.simpleworkflow.flow.annotations.Activities; import com.amazonaws.services.simpleworkflow.flow.annotations.ActivityRegistrationOptions; @ActivityRegistrationOptions(defaultTaskScheduleToStartTimeoutSeconds = 300, defaultTaskStartToCloseTimeoutSeconds = 10) @Activities(version="1.0") public interface GreeterActivities { public String getName(); public String getGreeting(String name); public void say(String what); HelloWorldWorkflow Activities Worker API Version 2021-04-28 10 AWS Flow Framework for Java } Developer Guide This interface wasn't strictly necessary for HelloWorld, but it is for an AWS Flow Framework for Java application. Notice that the interface definition itself hasn't changed. However, you must apply two AWS Flow Framework for Java annotations, @ActivityRegistrationOptions and @Activities, to the interface definition. The annotations provide configuration information and direct the AWS Flow Framework for Java annotation processor to use the interface definition to generate an activities client class, which is discussed later. @ActivityRegistrationOptions has several named values that are used to configure the activities' behavior. HelloWorldWorkflow specifies two timeouts: • defaultTaskScheduleToStartTimeoutSeconds specifies how long the tasks can be queued in the activities task list, and is set to 300 seconds (5 minutes). • defaultTaskStartToCloseTimeoutSeconds specifies the maximum time the activity can take to perform the task and is set to 10 seconds. These timeouts ensure that the activity completes its task in a reasonable amount of time. If either timeout is exceeded, the framework generates an error and the workflow worker must decide how to handle the issue. For a discussion of how to handle such errors, see Error Handling. @Activities has several values, but typically it just specifies the activities' version number, which allows you to keep track of different generations of activity implementations. If you change an activity interface after you have registered it with Amazon SWF, including changing the @ActivityRegistrationOptions values, you must use a new version number. HelloWorldWorkflow implements the activity methods in GreeterActivitiesImpl, as follows: public class GreeterActivitiesImpl implements GreeterActivities { @Override public String getName() { return "World"; } @Override public String getGreeting(String name) { return "Hello " + name; } @Override public void say(String what) { System.out.println(what); HelloWorldWorkflow Activities Worker API Version 2021-04-28 11 AWS Flow Framework for Java Developer Guide } } Notice that the code is identical to the HelloWorld implementation. At its core, an AWS Flow Framework activity is just a method that executes some code and perhaps returns a result. The difference between a standard application and an Amazon SWF workflow application lies in how the workflow executes the activities, where the activities execute, and how the results are returned to the workflow worker. HelloWorldWorkflow Workflow Worker An Amazon SWF workflow worker has three basic components. • A workflow implementation, which is a class that performs the workflow-related tasks. • An activities
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Framework for Java Developer Guide } } Notice that the code is identical to the HelloWorld implementation. At its core, an AWS Flow Framework activity is just a method that executes some code and perhaps returns a result. The difference between a standard application and an Amazon SWF workflow application lies in how the workflow executes the activities, where the activities execute, and how the results are returned to the workflow worker. HelloWorldWorkflow Workflow Worker An Amazon SWF workflow worker has three basic components. • A workflow implementation, which is a class that performs the workflow-related tasks. • An activities client class, which is basically a proxy for the activities class and is used by a workflow implementation to execute activity methods asynchronously. • A WorkflowWorker class, which manages the interaction between the workflow and Amazon SWF. This section discusses the workflow implementation and activities client; the WorkflowWorker class is discussed later. HelloWorldWorkflow defines the workflow interface in GreeterWorkflow, as follows: import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; import com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 3600) public interface GreeterWorkflow { @Execute(version = "1.0") public void greet(); } This interface also isn't strictly necessary for HelloWorld but is essential for an AWS Flow Framework for Java application. You must apply two AWS Flow Framework for Java annotations, @Workflow and @WorkflowRegistrationOptions, to the workflow interface definition. The HelloWorldWorkflow Workflow Worker API Version 2021-04-28 12 AWS Flow Framework for Java Developer Guide annotations provide configuration information and also direct the AWS Flow Framework for Java annotation processor to generate a workflow client class based on the interface, as discussed later. @Workflow has one optional parameter, dataConverter, which is often used with its default value, NullDataConverter, which indicates that JsonDataConverter should be used. @WorkflowRegistrationOptions also has a number of optional parameters that can be used to configure the workflow worker. Here, we set defaultExecutionStartToCloseTimeoutSeconds—which specifies how long the workflow can run—to 3600 seconds (1 hour). The GreeterWorkflow interface definition differs from HelloWorld in one important way, the @Execute annotation. Workflow interfaces specify the methods that can be called by applications such as the workflow starter and are limited to a handful of methods, each with a particular role. The framework doesn't specify a name or parameter list for workflow interface methods; you use a name and parameter list that is suitable for your workflow and apply an AWS Flow Framework for Java annotation to identify the method's role. @Execute has two purposes: • It identifies greet as the workflow's entry point—the method that the workflow starter calls to start the workflow. In general, an entry point can take one or more parameters, which allows the starter to initialize the workflow, but this example doesn't require initialization. • It specifies the workflow's version number, which allows you to keep track of different generations of workflow implementations. To change a workflow interface after you have registered it with Amazon SWF, including changing the timeout values, you must use a new version number. For information about the other methods that can be included in a workflow interface, see Workflow and Activity Contracts. HelloWorldWorkflow implements the workflow in GreeterWorkflowImpl, as follows: import com.amazonaws.services.simpleworkflow.flow.core.Promise; public class GreeterWorkflowImpl implements GreeterWorkflow { private GreeterActivitiesClient operations = new GreeterActivitiesClientImpl(); public void greet() { Promise<String> name = operations.getName(); HelloWorldWorkflow Workflow Worker API Version 2021-04-28 13 AWS Flow Framework for Java Developer Guide Promise<String> greeting = operations.getGreeting(name); operations.say(greeting); } } The code is similar to HelloWorld, but with two important differences. • GreeterWorkflowImpl creates an instance of GreeterActivitiesClientImpl, the activities client, instead of GreeterActivitiesImpl, and executes activities by calling methods on the client object. • The name and greeting activities return Promise<String> objects instead of String objects. HelloWorld is a standard Java application that runs locally as a single process, so GreeterWorkflowImpl can implement the workflow topology by simply creating an instance of GreeterActivitiesImpl, calling the methods in order, and passing the return values from one activity to the next. With an Amazon SWF workflow, an activity's task is still performed by an activity method from GreeterActivitiesImpl. However, the method doesn't necessarily run in the same process as the workflow—it might not even run on the same system—and the workflow needs to execute the activity asynchronously. These requirements raise the following issues: • How to execute an activity method that might be running in a different process, perhaps on a different system. • How to execute an activity method asynchronously. • How to manage activities' input and return values. For example, if the Activity A return value is an input to Activity B, you must ensure that Activity B doesn't execute until Activity A is complete. You can implement a variety of workflow topologies through the application's control flow by using familiar Java flow control combined with the activities client and the Promise<T>. Activities Client GreeterActivitiesClientImpl is basically a
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the following issues: • How to execute an activity method that might be running in a different process, perhaps on a different system. • How to execute an activity method asynchronously. • How to manage activities' input and return values. For example, if the Activity A return value is an input to Activity B, you must ensure that Activity B doesn't execute until Activity A is complete. You can implement a variety of workflow topologies through the application's control flow by using familiar Java flow control combined with the activities client and the Promise<T>. Activities Client GreeterActivitiesClientImpl is basically a proxy for GreeterActivitiesImpl that allows a workflow implementation to execute the GreeterActivitiesImpl methods asynchronously. The GreeterActivitiesClient and GreeterActivitiesClientImpl classes are generated automatically for you using the information provided in the annotations applied to your GreeterActivities class. You don't need to implement these yourself. HelloWorldWorkflow Workflow Worker API Version 2021-04-28 14 AWS Flow Framework for Java Developer Guide Note Eclipse generates these classes when you save your project. You can view the generated code in the .apt_generated subdirectory of your project directory. To avoid compilation errors in your GreeterWorkflowImpl class, it is a good practice to move the .apt_generated directory to the top of the Order and Export tab of the Java Build Path dialog box. A workflow worker executes an activity by calling the corresponding client method. The method is asynchronous and immediately returns a Promise<T> object, where T is the activity's return type. The returned Promise<T> object is basically a placeholder for the value that the activity method will eventually return. • When the activities client method returns, the Promise<T> object is initially in an unready state, which indicates that the object doesn't yet represent a valid return value. • When the corresponding activity method completes its task and returns, the framework assigns the return value to the Promise<T> object and puts it in the ready state. Promise<T> Type The primary purpose of Promise<T> objects is to manage data flow between asynchronous components and control when they execute. It relieves your application of the need to explicitly manage synchronization or depend on mechanisms such as timers to ensure that asynchronous components don't execute prematurely. When you call an activities client method, it immediately returns but the framework defers executing the corresponding activity method until any input Promise<T> objects are ready and represent valid data. From GreeterWorkflowImpl perspective, all three activities client methods return immediately. From the GreeterActivitiesImpl perspective, the framework doesn't call getGreeting until name completes, and doesn't call say until getGreeting completes. By using Promise<T> to pass data from one activity to the next, HelloWorldWorkflow not only ensures that activity methods don't attempt to use invalid data, it also controls when the activities execute and implicitly defines the workflow topology. Passing each activity's Promise<T> return value to the next activity requires the activities to execute in sequence, defining the linear topology discussed earlier. With AWS Flow Framework for Java, you don't need to use any special modeling HelloWorldWorkflow Workflow Worker API Version 2021-04-28 15 AWS Flow Framework for Java Developer Guide code to define even complex topologies, just standard Java flow control and Promise<T>. For an example of how to implement a simple parallel topology, see HelloWorldWorkflowParallel Activities Worker. Note When an activity method such as say doesn't return a value, the corresponding client method returns a Promise<Void> object. The object doesn't represent data, but it is initially unready and becomes ready when the activity completes. You can therefore pass a Promise<Void> object to other activities client methods to ensure that they defer execution until the original activity completes. Promise<T> allows a workflow implementation to use activities client methods and their return values much like synchronous methods. However, you must be careful about accessing a Promise<T> object's value. Unlike the Java Future<T> type, the framework handles synchronization for Promise<T>, not the application. If you call Promise<T>.get and the object isn't ready, get throws an exception. Notice that HelloWorldWorkflow never accesses a Promise<T> object directly; it simply passes the objects from one activity to the next. When an object becomes ready, the framework extracts the value and passes it to the activity method as a standard type. Promise<T> objects should be accessed only by asynchronous code, where the framework guarantees that the object is ready and represents a valid value. HelloWorldWorkflow deals with this issue by passing Promise<T> objects only to activities client methods. You can access a Promise<T> object's value in your workflow implementation by passing the object to an asynchronous workflow method, which behaves much like an activity. For an example, see HelloWorldWorkflowAsync Application. HelloWorldWorkflow Workflow and Activities Implementation The workflow and activities implementations have associated worker classes, ActivityWorker and WorkflowWorker. They handle communication between Amazon SWF and the activities and workflow implementations by polling the appropriate
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should be accessed only by asynchronous code, where the framework guarantees that the object is ready and represents a valid value. HelloWorldWorkflow deals with this issue by passing Promise<T> objects only to activities client methods. You can access a Promise<T> object's value in your workflow implementation by passing the object to an asynchronous workflow method, which behaves much like an activity. For an example, see HelloWorldWorkflowAsync Application. HelloWorldWorkflow Workflow and Activities Implementation The workflow and activities implementations have associated worker classes, ActivityWorker and WorkflowWorker. They handle communication between Amazon SWF and the activities and workflow implementations by polling the appropriate Amazon SWF task list for tasks, executing the appropriate method for each task, and managing the data flow. For details, see AWS Flow Framework Basic Concepts: Application Structure HelloWorldWorkflow Workflow and Activities Implementation API Version 2021-04-28 16 AWS Flow Framework for Java Developer Guide To associate the activity and workflow implementations with the corresponding worker objects, you implement one or more worker applications which: • Register workflows or activities with Amazon SWF. • Create worker objects and associate them with the workflow or activity worker implementations. • Direct the worker objects to start communicating with Amazon SWF. If you want to run the workflow and activities as separate processes, you must implement separate workflow and activities worker hosts. For an example, see HelloWorldWorkflowDistributed Application. For simplicity, HelloWorldWorkflow implements a single worker host that runs activities and workflow workers in the same process, as follows: import com.amazonaws.ClientConfiguration; import com.amazonaws.auth.AWSCredentials; import com.amazonaws.auth.BasicAWSCredentials; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflow; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClient; import com.amazonaws.services.simpleworkflow.flow.ActivityWorker; import com.amazonaws.services.simpleworkflow.flow.WorkflowWorker; public class GreeterWorker { public static void main(String[] args) throws Exception { ClientConfiguration config = new ClientConfiguration().withSocketTimeout(70*1000); String swfAccessId = System.getenv("AWS_ACCESS_KEY_ID"); String swfSecretKey = System.getenv("AWS_SECRET_KEY"); AWSCredentials awsCredentials = new BasicAWSCredentials(swfAccessId, swfSecretKey); AmazonSimpleWorkflow service = new AmazonSimpleWorkflowClient(awsCredentials, config); service.setEndpoint("https://swf.us-east-1.amazonaws.com"); String domain = "helloWorldWalkthrough"; String taskListToPoll = "HelloWorldList"; ActivityWorker aw = new ActivityWorker(service, domain, taskListToPoll); aw.addActivitiesImplementation(new GreeterActivitiesImpl()); aw.start(); WorkflowWorker wfw = new WorkflowWorker(service, domain, taskListToPoll); HelloWorldWorkflow Workflow and Activities Implementation API Version 2021-04-28 17 AWS Flow Framework for Java Developer Guide wfw.addWorkflowImplementationType(GreeterWorkflowImpl.class); wfw.start(); } } GreeterWorker has no HelloWorld counterpart, so you must add a Java class named GreeterWorker to the project and copy the example code to that file. The first step is to create and configure an AmazonSimpleWorkflowClient object, which invokes the underlying Amazon SWF service methods. To do so, GreeterWorker: 1. Creates a ClientConfiguration object and specifies a socket timeout of 70 seconds. This value specifies long to wait for data to be transferred over an established open connection before closing the socket. 2. Creates a BasicAWSCredentials object to identify the AWS account and passes the account keys to the constructor. For convenience, and to avoid exposing them as plain text in the code, the keys are stored as environment variables. 3. Creates an AmazonSimpleWorkflowClient object to represent the workflow, and passes the BasicAWSCredentials and ClientConfiguration objects to the constructor. 4. Sets the client object's service endpoint URL. Amazon SWF is currently available in all AWS regions. For convenience, GreeterWorker defines two string constants. • domain is the workflow's Amazon SWF domain name, which you created when you set up your Amazon SWF account. HelloWorldWorkflow assumes that you are running the workflow in the "helloWorldWalkthrough" domain. • taskListToPoll is the name of the task lists that Amazon SWF uses to manage communication between the workflow and activities workers. You can set the name to any convenient string. HelloWorldWorkflow uses "HelloWorldList" for both workflow and activity task lists. Behind the scenes, the names end up in different namespaces, so the two task lists are distinct. GreeterWorker uses the string constants and the AmazonSimpleWorkflowClient object to create worker objects, which manage the interaction between the activities and worker implementations and Amazon SWF. In particular, the worker objects handle the task of polling the appropriate task list for tasks. HelloWorldWorkflow Workflow and Activities Implementation API Version 2021-04-28 18 AWS Flow Framework for Java Developer Guide GreeterWorker creates an ActivityWorker object and configures it to handle GreeterActivitiesImpl by adding a new class instance. GreeterWorker then calls the ActivityWorker object's start method, which directs the object to start polling the specified activities task list. GreeterWorker creates a WorkflowWorker object and configures it to handle GreeterWorkflowImpl by adding the class file name, GreeterWorkflowImpl.class. It then calls the WorkflowWorker object's start method, which directs the object to start polling the specified workflow task list. You can run GreeterWorker successfully at this point. It registers the workflow and activities with Amazon SWF and starts the worker objects polling their respective task lists. To verify this, run GreeterWorker and go to the Amazon SWF console and select helloWorldWalkthrough from the list of domains. If you choose Workflow Types in the Navigation pane, you should see GreeterWorkflow.greet: HelloWorldWorkflow Workflow and Activities Implementation API Version 2021-04-28 19 AWS Flow Framework for Java
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adding the class file name, GreeterWorkflowImpl.class. It then calls the WorkflowWorker object's start method, which directs the object to start polling the specified workflow task list. You can run GreeterWorker successfully at this point. It registers the workflow and activities with Amazon SWF and starts the worker objects polling their respective task lists. To verify this, run GreeterWorker and go to the Amazon SWF console and select helloWorldWalkthrough from the list of domains. If you choose Workflow Types in the Navigation pane, you should see GreeterWorkflow.greet: HelloWorldWorkflow Workflow and Activities Implementation API Version 2021-04-28 19 AWS Flow Framework for Java Developer Guide If you choose Activity Types, the GreeterActivities methods are displayed: However, if you choose Workflow Executions, you will not see any active executions. Although the workflow and activities workers are polling for tasks, we have not yet started a workflow execution. HelloWorldWorkflow Starter The final piece of the puzzle is to implement a workflow starter, which is an application that starts the workflow execution. The execution state is stored by Amazon SWF, so that you can view its history and execution status. HelloWorldWorkflow implements a workflow starter by modifying the GreeterMain class, as follows: import com.amazonaws.ClientConfiguration; import com.amazonaws.auth.AWSCredentials; import com.amazonaws.auth.BasicAWSCredentials; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflow; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClient; HelloWorldWorkflow Starter API Version 2021-04-28 20 AWS Flow Framework for Java Developer Guide public class GreeterMain { public static void main(String[] args) throws Exception { ClientConfiguration config = new ClientConfiguration().withSocketTimeout(70*1000); String swfAccessId = System.getenv("AWS_ACCESS_KEY_ID"); String swfSecretKey = System.getenv("AWS_SECRET_KEY"); AWSCredentials awsCredentials = new BasicAWSCredentials(swfAccessId, swfSecretKey); AmazonSimpleWorkflow service = new AmazonSimpleWorkflowClient(awsCredentials, config); service.setEndpoint("https://swf.us-east-1.amazonaws.com"); String domain = "helloWorldWalkthrough"; GreeterWorkflowClientExternalFactory factory = new GreeterWorkflowClientExternalFactoryImpl(service, domain); GreeterWorkflowClientExternal greeter = factory.getClient("someID"); greeter.greet(); } } GreeterMain creates an AmazonSimpleWorkflowClient object by using the same code as GreeterWorker. It then creates a GreeterWorkflowClientExternal object, which acts as a proxy for the workflow in much the same way that the activities client created in GreeterWorkflowClientImpl acts as a proxy for the activity methods. Rather than create a workflow client object by using new, you must: 1. Create an external client factory object and pass the AmazonSimpleWorkflowClient object and Amazon SWF domain name to the constructor. The client factory object is created by the framework's annotation processor, which creates the object name by simply appending "ClientExternalFactoryImpl" to the workflow interface name. 2. Create an external client object by calling the factory object's getClient method, which creates the object name by appending "ClientExternal" to the workflow interface name. You can optionally pass getClient a string which Amazon SWF will use to identify this instance of the workflow. Otherwise, Amazon SWF represents a workflow instance by using a generated GUID. HelloWorldWorkflow Starter API Version 2021-04-28 21 AWS Flow Framework for Java Developer Guide The client returned from the factory will only create workflows that are named with the string passed into the getClient method, (the client returned from the factory already has state in Amazon SWF). To run a workflow with a different id, you need to go back to the factory and create a new client with the different id specified. The workflow client exposes a greet method that GreeterMain calls to begin the workflow, as greet() was the method specified with the @Execute annotation. Note The annotation processor also creates an internal client factory object that is used to create child workflows. For details, see Child Workflow Executions. Shut down GreeterWorker for the moment if it is still running, and run GreeterMain. You should now see someID on the Amazon SWF console's list of active workflow executions:. If you choose someID and choose the Events tab, the events are displayed: HelloWorldWorkflow Starter API Version 2021-04-28 22 AWS Flow Framework for Java Developer Guide Note If you started GreeterWorker earlier, and it is still running, you will see a longer event list for reasons discussed shortly. Stop GreeterWorker and try running GreaterMain again. The Events tab shows only two events: • WorkflowExecutionStarted indicates that the workflow has started executing. • DecisionTaskScheduled indicates that Amazon SWF has queued the first decision task. The reason that the workflow is blocked at the first decision task is that the workflow is distributed across two applications, GreeterMain and GreeterWorker. GreeterMain started the workflow execution, but GreeterWorker isn't running, so the workers aren't polling the lists and executing tasks. You can run either application independently, but you need both for workflow execution to proceed beyond the first decision task. If you now run GreeterWorker, the workflow and activity workers will start polling and the various tasks will be completed rapidly. If you now check the Events tab, the first batch of events is displayed. HelloWorldWorkflow Starter API Version 2021-04-28 23 AWS Flow Framework for Java Developer Guide You can choose individual events to get more information. By the time you've finished looking, the workflow should have printed "Hello World!" to
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the workers aren't polling the lists and executing tasks. You can run either application independently, but you need both for workflow execution to proceed beyond the first decision task. If you now run GreeterWorker, the workflow and activity workers will start polling and the various tasks will be completed rapidly. If you now check the Events tab, the first batch of events is displayed. HelloWorldWorkflow Starter API Version 2021-04-28 23 AWS Flow Framework for Java Developer Guide You can choose individual events to get more information. By the time you've finished looking, the workflow should have printed "Hello World!" to your console. After the workflow completes, it no longer appears on the list of active executions. However, if you want to review it, choose the Closed execution status button and then choose List Executions. This displays all the completed workflow instances in the specified domain (helloWorldWalkthrough) that have not exceeded their retention time, which you specified when you created the domain. HelloWorldWorkflow Starter API Version 2021-04-28 24 AWS Flow Framework for Java Developer Guide Notice that each workflow instance has a unique Run ID value. You can use the same Workflow ID for different workflow instances, but only for one active execution at a time. HelloWorldWorkflowAsync Application Sometimes, it's preferable to have a workflow perform certain tasks locally instead of using an activity. However, workflow tasks often involve processing the values represented by Promise<T> objects. If you pass a Promise<T> object to a synchronous workflow method, the method executes immediately but it can't access the Promise<T> object's value until the object is ready. You could poll Promise<T>.isReady until it returns true, but that's inefficient and the method might block for a long time. A better approach is to use an asynchronous method. An asynchronous method is implemented much like a standard method—often as a member of the workflow implementation class—and runs in the workflow implementation's context. You designate it as an asynchronous method by applying an @Asynchronous annotation, which directs the framework to treat it much like an activity. HelloWorldWorkflowAsync Application API Version 2021-04-28 25 AWS Flow Framework for Java Developer Guide • When a workflow implementation calls an asynchronous method, it returns immediately. Asynchronous methods typically return a Promise<T> object, which becomes ready when the method completes. • If you pass an asynchronous method one or more Promise<T> objects, it defers execution until all the input objects are ready. An asynchronous method can therefore access its input Promise<T> values without risking an exception. Note Because of the way that the AWS Flow Framework for Java executes the workflow, asynchronous methods typically execute multiple times, so you should use them only for quick low-overhead tasks. You should use activities to perform lengthy tasks such as large computations. For details, see AWS Flow Framework Basic Concepts: Distributed Execution. This topic is a walkthrough of HelloWorldWorkflowAsync, a modified version of HelloWorldWorkflow that replaces one of the activities with an asynchronous method. To implement the application, create a copy of the helloWorld.HelloWorldWorkflow package in your project directory and name it helloWorld.HelloWorldWorkflowAsync. Note This topic builds on the concepts and files presented in the HelloWorld Application and HelloWorldWorkflow Application topics. Familiarize yourself with the files and concepts presented in those topics before proceeding. The following sections describe how to modify the original HelloWorldWorkflow code to use an asynchronous method. HelloWorldWorkflowAsync Activities Implementation HelloWorldWorkflowAsync implements its activities worker interface in GreeterActivities, as follows: import com.amazonaws.services.simpleworkflow.flow.annotations.Activities; import com.amazonaws.services.simpleworkflow.flow.annotations.ActivityRegistrationOptions; HelloWorldWorkflowAsync Activities Implementation API Version 2021-04-28 26 AWS Flow Framework for Java Developer Guide @Activities(version="2.0") @ActivityRegistrationOptions(defaultTaskScheduleToStartTimeoutSeconds = 300, defaultTaskStartToCloseTimeoutSeconds = 10) public interface GreeterActivities { public String getName(); public void say(String what); } This interface is similar to the one used by HelloWorldWorkflow, with the following exceptions: • It omits the getGreeting activity; that task is now handled by an asynchronous method. • The version number is set to 2.0. After you have registered an activities interface with Amazon SWF, you can't modify it unless you change the version number. The remaining activity method implementations are identical to HelloWorldWorkflow. Just delete getGreeting from GreeterActivitiesImpl. HelloWorldWorkflowAsync Workflow Implementation HelloWorldWorkflowAsync defines the workflow interface as follows: import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; import com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 3600) public interface GreeterWorkflow { @Execute(version = "2.0") public void greet(); } The interface is identical to HelloWorldWorkflow apart from a new version number. As with activities, if you want to change a registered workflow, you must change its version. HelloWorldWorkflowAsync implements the workflow as follows: import com.amazonaws.services.simpleworkflow.flow.annotations.Asynchronous; HelloWorldWorkflowAsync Workflow Implementation API Version 2021-04-28 27 AWS Flow Framework for Java Developer Guide import com.amazonaws.services.simpleworkflow.flow.core.Promise; public class GreeterWorkflowImpl implements GreeterWorkflow { private GreeterActivitiesClient operations = new GreeterActivitiesClientImpl(); @Override public void greet() { Promise<String> name = operations.getName(); Promise<String> greeting = getGreeting(name); operations.say(greeting); } @Asynchronous private Promise<String> getGreeting(Promise<String> name) { String returnString = "Hello " + name.get() +
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@Execute(version = "2.0") public void greet(); } The interface is identical to HelloWorldWorkflow apart from a new version number. As with activities, if you want to change a registered workflow, you must change its version. HelloWorldWorkflowAsync implements the workflow as follows: import com.amazonaws.services.simpleworkflow.flow.annotations.Asynchronous; HelloWorldWorkflowAsync Workflow Implementation API Version 2021-04-28 27 AWS Flow Framework for Java Developer Guide import com.amazonaws.services.simpleworkflow.flow.core.Promise; public class GreeterWorkflowImpl implements GreeterWorkflow { private GreeterActivitiesClient operations = new GreeterActivitiesClientImpl(); @Override public void greet() { Promise<String> name = operations.getName(); Promise<String> greeting = getGreeting(name); operations.say(greeting); } @Asynchronous private Promise<String> getGreeting(Promise<String> name) { String returnString = "Hello " + name.get() + "!"; return Promise.asPromise(returnString); } } HelloWorldWorkflowAsync replaces the getGreeting activity with a getGreeting asynchronous method but the greet method works in much the same way: 1. Execute the getName activity, which immediately returns a Promise<String> object, name, that represents the name. 2. Call the getGreeting asynchronous method and pass it the name object. getGreeting immediately returns a Promise<String> object, greeting, that represents the greeting. 3. Execute the say activity and pass it the greeting object. 4. When getName completes, name becomes ready and getGreeting uses its value to construct the greeting. 5. When getGreeting completes, greeting becomes ready and say prints the string to the console. The difference is that, instead of calling the activities client to execute a getGreeting activity, greet calls the asynchronous getGreeting method. The net result is the same, but the getGreeting method works somewhat differently than the getGreeting activity. • The workflow worker uses standard function call semantics to execute getGreeting. However, the asynchronous execution of the activity is mediated by Amazon SWF. • getGreeting runs in the workflow implementation's process. HelloWorldWorkflowAsync Workflow Implementation API Version 2021-04-28 28 AWS Flow Framework for Java Developer Guide • getGreeting returns a Promise<String> object rather than a String object. To get the String value held by the Promise, you call its get() method. However, because the activity is being run asynchronously, its return value might not be ready immediately; get() will raise an exception until the return value of the asynchronous method is available. For more information about how Promise works, see AWS Flow Framework Basic Concepts: Data Exchange Between Activities and Workflows. getGreeting creates a return value by passing the greeting string to the static Promise.asPromise method. This method creates a Promise<T> object of the appropriate type, sets the value, and puts it in the ready state. HelloWorldWorkflowAsync Workflow and Activities Host and Starter HelloWorldWorkflowAsync implements GreeterWorker as the host class for the workflow and activity implementations. It is identical to the HelloWorldWorkflow implementation except for the taskListToPoll name, which is set to "HelloWorldAsyncList". import com.amazonaws.ClientConfiguration; import com.amazonaws.auth.AWSCredentials; import com.amazonaws.auth.BasicAWSCredentials; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflow; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClient; import com.amazonaws.services.simpleworkflow.flow.ActivityWorker; import com.amazonaws.services.simpleworkflow.flow.WorkflowWorker; public class GreeterWorker { public static void main(String[] args) throws Exception { ClientConfiguration config = new ClientConfiguration().withSocketTimeout(70*1000); String swfAccessId = System.getenv("AWS_ACCESS_KEY_ID"); String swfSecretKey = System.getenv("AWS_SECRET_KEY"); AWSCredentials awsCredentials = new BasicAWSCredentials(swfAccessId, swfSecretKey); AmazonSimpleWorkflow service = new AmazonSimpleWorkflowClient(awsCredentials, config); service.setEndpoint("https://swf.us-east-1.amazonaws.com"); String domain = "helloWorldWalkthrough"; HelloWorldWorkflowAsync Workflow and Activities Host and Starter API Version 2021-04-28 29 AWS Flow Framework for Java Developer Guide String taskListToPoll = "HelloWorldAsyncList"; ActivityWorker aw = new ActivityWorker(service, domain, taskListToPoll); aw.addActivitiesImplementation(new GreeterActivitiesImpl()); aw.start(); WorkflowWorker wfw = new WorkflowWorker(service, domain, taskListToPoll); wfw.addWorkflowImplementationType(GreeterWorkflowImpl.class); wfw.start(); } } HelloWorldWorkflowAsync implements the workflow starter in GreeterMain; it is identical to the HelloWorldWorkflow implementation. To execute the workflow, run GreeterWorker and GreeterMain, just as with HelloWorldWorkflow. HelloWorldWorkflowDistributed Application With HelloWorldWorkflow and HelloWorldWorkflowAsync, Amazon SWF mediates the interaction between the workflow and activities implementations, but they run locally as a single process. GreeterMain is in a separate process, but it still runs on the same system. A key feature of Amazon SWF is that it supports distributed applications. For example, you could run the workflow worker on an Amazon EC2 instance, the workflow starter on a data center computer, and the activities on a client desktop computer. You can even run different activities on different systems. The HelloWorldWorkflowDistributed application extends HelloWorldWorkflowAsync to distribute the application across two systems and three processes. • The workflow and workflow starter run as separate processes on one system. • The activities run on a separate system. To implement the application, create a copy of the helloWorld.HelloWorldWorkflowAsync package in your project directory and name it helloWorld.HelloWorldWorkflowDistributed. The following sections describe how to modify the original HelloWorldWorkflowAsync code to distribute the application across two systems and three processes. HelloWorldWorkflowDistributed Application API Version 2021-04-28 30 AWS Flow Framework for Java Developer Guide You don't need to change the workflow or activities implementations to run them on separate systems, not even the version numbers. You also don't need to modify GreeterMain. All you need to change is the activities and workflow host. With HelloWorldWorkflowAsync, a single application serves as the workflow and activity host. To run the workflow and activity implementations on separate
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project directory and name it helloWorld.HelloWorldWorkflowDistributed. The following sections describe how to modify the original HelloWorldWorkflowAsync code to distribute the application across two systems and three processes. HelloWorldWorkflowDistributed Application API Version 2021-04-28 30 AWS Flow Framework for Java Developer Guide You don't need to change the workflow or activities implementations to run them on separate systems, not even the version numbers. You also don't need to modify GreeterMain. All you need to change is the activities and workflow host. With HelloWorldWorkflowAsync, a single application serves as the workflow and activity host. To run the workflow and activity implementations on separate systems, you must implement separate applications. Delete GreeterWorker from the project and add two new class files, GreeterWorkflowWorker and GreeterActivitiesWorker. HelloWorldWorkflowDistributed implements its activities host in GreeterActivitiesWorker, as follows: import com.amazonaws.ClientConfiguration; import com.amazonaws.auth.AWSCredentials; import com.amazonaws.auth.BasicAWSCredentials; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflow; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClient; import com.amazonaws.services.simpleworkflow.flow.ActivityWorker; public class GreeterActivitiesWorker { public static void main(String[] args) throws Exception { ClientConfiguration config = new ClientConfiguration().withSocketTimeout(70*1000); String swfAccessId = System.getenv("AWS_ACCESS_KEY_ID"); String swfSecretKey = System.getenv("AWS_SECRET_KEY"); AWSCredentials awsCredentials = new BasicAWSCredentials(swfAccessId, swfSecretKey); AmazonSimpleWorkflow service = new AmazonSimpleWorkflowClient(awsCredentials, config); service.setEndpoint("https://swf.us-east-1.amazonaws.com"); String domain = "helloWorldExamples"; String taskListToPoll = "HelloWorldAsyncList"; ActivityWorker aw = new ActivityWorker(service, domain, taskListToPoll); aw.addActivitiesImplementation(new GreeterActivitiesImpl()); aw.start(); } } HelloWorldWorkflowDistributed Application API Version 2021-04-28 31 AWS Flow Framework for Java Developer Guide HelloWorldWorkflowDistributed implements its workflow host in GreeterWorkflowWorker, as follows: import com.amazonaws.ClientConfiguration; import com.amazonaws.auth.AWSCredentials; import com.amazonaws.auth.BasicAWSCredentials; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflow; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClient; import com.amazonaws.services.simpleworkflow.flow.WorkflowWorker; public class GreeterWorkflowWorker { public static void main(String[] args) throws Exception { ClientConfiguration config = new ClientConfiguration().withSocketTimeout(70*1000); String swfAccessId = System.getenv("AWS_ACCESS_KEY_ID"); String swfSecretKey = System.getenv("AWS_SECRET_KEY"); AWSCredentials awsCredentials = new BasicAWSCredentials(swfAccessId, swfSecretKey); AmazonSimpleWorkflow service = new AmazonSimpleWorkflowClient(awsCredentials, config); service.setEndpoint("https://swf.us-east-1.amazonaws.com"); String domain = "helloWorldExamples"; String taskListToPoll = "HelloWorldAsyncList"; WorkflowWorker wfw = new WorkflowWorker(service, domain, taskListToPoll); wfw.addWorkflowImplementationType(GreeterWorkflowImpl.class); wfw.start(); } } Note that GreeterActivitiesWorker is just GreeterWorker without the WorkflowWorker code and GreeterWorkflowWorker is just GreeterWorker without the ActivityWorker code. To run the workflow: 1. Create a runnable JAR file with GreeterActivitiesWorker as the entry point. 2. Copy the JAR file from Step 1 to another system, which can be running any operating system that supports Java. HelloWorldWorkflowDistributed Application API Version 2021-04-28 32 AWS Flow Framework for Java Developer Guide 3. Ensure that AWS credentials with access to the same Amazon SWF domain are made available on the other system. 4. Run the JAR file. 5. On your development system, use Eclipse to run GreeterWorkflowWorker and GreeterMain. Other than the fact that the activities are running on a different system than the workflow worker and workflow starter, the workflow works in exactly the same way as HelloWorldAsync. However, because println call that prints "Hello World!" to the console is in the say activity, the output will appear on the system that is running the activities worker. HelloWorldWorkflowParallel Application The preceding versions of Hello World! all use a linear workflow topology. However, Amazon SWF isn't limited to linear topologies. The HelloWorldWorkflowParallel application is a modified version of HelloWorldWorkflow that uses a parallel topology, as shown in the following figure. With HelloWorldWorkflowParallel, getName and getGreeting run in parallel and each return part of the greeting. say then merges the two strings into a greeting, and prints it to the console. To implement the application, create a copy of the helloWorld.HelloWorldWorkflow package in your project directory and name it helloWorld.HelloWorldWorkflowParallel. The following sections describe how to modify the original HelloWorldWorkflow code to run getName and getGreeting in parallel. HelloWorldWorkflowParallel Activities Worker The HelloWorldWorkflowParallel activities interface is implemented in GreeterActivities, as shown in the following example. import com.amazonaws.services.simpleworkflow.flow.annotations.Activities; HelloWorldWorkflowParallel Application API Version 2021-04-28 33 AWS Flow Framework for Java import Developer Guide com.amazonaws.services.simpleworkflow.flow.annotations.ActivityRegistrationOptions; @Activities(version="5.0") @ActivityRegistrationOptions(defaultTaskScheduleToStartTimeoutSeconds = 300, defaultTaskStartToCloseTimeoutSeconds = 10) public interface GreeterActivities { public String getName(); public String getGreeting(); public void say(String greeting, String name); } The interface is similar to HelloWorldWorkflow, with the following exceptions: • getGreeting doesn't take any input; it simply returns a greeting string. • say takes two input strings, the greeting and the name. • The interface has a new version number, which is required any time that you change a registered interface. HelloWorldWorkflowParallel implements the activities in GreeterActivitiesImpl, as follows: public class GreeterActivitiesImpl implements GreeterActivities { @Override public String getName() { return "World!"; } @Override public String getGreeting() { return "Hello "; } @Override public void say(String greeting, String name) { System.out.println(greeting + name); } } getName and getGreeting now simply return half of the greeting string. say concatenates the two pieces to produce the complete phrase, and prints it to the console. HelloWorldWorkflowParallel Activities Worker API Version 2021-04-28 34 AWS Flow Framework for Java Developer Guide HelloWorldWorkflowParallel Workflow Worker The HelloWorldWorkflowParallel workflow interface is implemented in GreeterWorkflow, as follows: import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; import com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 3600) public interface GreeterWorkflow { @Execute(version = "5.0") public void greet(); } The class is identical to the HelloWorldWorkflow
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{ return "Hello "; } @Override public void say(String greeting, String name) { System.out.println(greeting + name); } } getName and getGreeting now simply return half of the greeting string. say concatenates the two pieces to produce the complete phrase, and prints it to the console. HelloWorldWorkflowParallel Activities Worker API Version 2021-04-28 34 AWS Flow Framework for Java Developer Guide HelloWorldWorkflowParallel Workflow Worker The HelloWorldWorkflowParallel workflow interface is implemented in GreeterWorkflow, as follows: import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; import com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 3600) public interface GreeterWorkflow { @Execute(version = "5.0") public void greet(); } The class is identical to the HelloWorldWorkflow version, except that the version number has been changed to match the activities worker. The workflow is implemented in GreeterWorkflowImpl, as follows: import com.amazonaws.services.simpleworkflow.flow.core.Promise; public class GreeterWorkflowImpl implements GreeterWorkflow { private GreeterActivitiesClient operations = new GreeterActivitiesClientImpl(); public void greet() { Promise<String> name = operations.getName(); Promise<String> greeting = operations.getGreeting(); operations.say(greeting, name); } } At a glance, this implementation looks very similar to HelloWorldWorkflow; the three activities client methods execute in sequence. However, the activities don't. • HelloWorldWorkflow passed name to getGreeting. Because name was a Promise<T> object, getGreeting deferred executing the activity until getName completed, so the two activities executed in sequence. HelloWorldWorkflowParallel Workflow Worker API Version 2021-04-28 35 AWS Flow Framework for Java Developer Guide • HelloWorldWorkflowParallel doesn't pass any input getName or getGreeting. Neither method defers execution and the associated activity methods execute immediately, in parallel. The say activity takes both greeting and name as input parameters. Because they are Promise<T> objects, say defers execution until both activities complete, and then constructs and prints the greeting. Notice that HelloWorldWorkflowParallel doesn't use any special modeling code to define the workflow topology. It does it implicitly by using standard Java flow control and taking advantage of the properties of Promise<T> objects. AWS Flow Framework for Java applications can implement even complex topologies simply by using Promise<T> objects in conjunction with conventional Java control flow constructs. HelloWorldWorkflowParallel Workflow and Activities Host and Starter HelloWorldWorkflowParallel implements GreeterWorker as the host class for the workflow and activity implementations. It is identical to the HelloWorldWorkflow implementation except for the taskListToPoll name, which is set to "HelloWorldParallelList". HelloWorldWorkflowParallel implements the workflow starter in GreeterMain, and it is identical to the HelloWorldWorkflow implementation. To execute the workflow, run GreeterWorker and GreeterMain, just as with HelloWorldWorkflow. HelloWorldWorkflowParallel Workflow and Activities Host and Starter API Version 2021-04-28 36 AWS Flow Framework for Java Developer Guide Understanding AWS Flow Framework for Java The AWS Flow Framework for Java works with Amazon SWF to make it easy to create scalable and fault-tolerant applications to perform asynchronous tasks that may be long running, remote, or both. The "Hello World!" examples in What is the AWS Flow Framework for Java? introduced the basics of how to use the AWS Flow Framework to implement basic workflow applications. This section provides conceptual information about how AWS Flow Framework applications work. The first section summarizes the basic structure of an AWS Flow Framework application, and the remaining sections provide further detail about how AWS Flow Framework applications work. Topics • AWS Flow Framework Basic Concepts: Application Structure • AWS Flow Framework Basic Concepts: Reliable Execution • AWS Flow Framework Basic Concepts: Distributed Execution • AWS Flow Framework Basic Concepts: Task Lists and Task Execution • AWS Flow Framework Basic Concepts: Scalable Applications • AWS Flow Framework Basic Concepts: Data Exchange Between Activities and Workflows • AWS Flow Framework Basic Concepts: Data Exchange Between Applications and Workflow Executions • Amazon SWF Timeout Types AWS Flow Framework Basic Concepts: Application Structure Conceptually, an AWS Flow Framework application consists of three basic components: workflow starters, workflow workers, and activity workers. One or more host applications are responsible for registering the workers (workflow and activity) with Amazon SWF, starting the workers, and handling cleanup. The workers handle the mechanics of executing the workflow and may be implemented on several hosts. This diagram represents a basic AWS Flow Framework application: Application Structure API Version 2021-04-28 37 AWS Flow Framework for Java Developer Guide Note Implementing these components in three separate applications is convenient conceptually, but you can create applications to implement this functionality in a variety of ways. For example, you can use a single host application for the activity and workflow workers, or use separate activity and workflow hosts. You can also have multiple activity workers, each handling a different set of activities on separate hosts, and so on. The three AWS Flow Framework components interact indirectly by sending HTTP requests to Amazon SWF, which manages the requests. Amazon SWF does the following: • Maintains one or more decision task lists, which determine the next step to be performed by a workflow worker. Application Structure API Version 2021-04-28 38 AWS Flow Framework for Java Developer Guide • Maintains one or
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can use a single host application for the activity and workflow workers, or use separate activity and workflow hosts. You can also have multiple activity workers, each handling a different set of activities on separate hosts, and so on. The three AWS Flow Framework components interact indirectly by sending HTTP requests to Amazon SWF, which manages the requests. Amazon SWF does the following: • Maintains one or more decision task lists, which determine the next step to be performed by a workflow worker. Application Structure API Version 2021-04-28 38 AWS Flow Framework for Java Developer Guide • Maintains one or more activities task lists, which determine which tasks will be performed by an activity worker. • Maintains a detailed step-by-step history of the workflow's execution. With the AWS Flow Framework, your application code doesn't need to deal directly with many of the details shown in the figure, such as sending HTTP requests to Amazon SWF. You simply call AWS Flow Framework methods and the framework handles the details behind the scenes. Role of the Activity Worker The activity worker performs the various tasks that the workflow must accomplish. It consists of: • The activities implementation, which includes a set of activity methods that perform particular tasks for the workflow. • An ActivityWorker object, which uses HTTP long poll requests to poll Amazon SWF for activity tasks to be performed. When a task is needed, Amazon SWF responds to the request by sending the information required to perform the task. The ActivityWorker object then calls the appropriate activity method, and returns the results to Amazon SWF. Role of the Workflow Worker The workflow worker orchestrates the execution of the various activities, manages data flow, and handles failed activities. It consists of: • The workflow implementation, which includes the activity orchestration logic, handles failed activities, and so on. • An activities client, which serves as a proxy for the activity worker and enables the workflow worker to schedule activities to be executed asynchronously. • A WorkflowWorker object, which uses HTTP long poll requests to poll Amazon SWF for decision tasks. If there are tasks on the workflow task list, Amazon SWF responds to the request by returning the information that is required to perform the task. The framework then executes the workflow to perform the task and returns the results to Amazon SWF. Role of the Activity Worker API Version 2021-04-28 39 AWS Flow Framework for Java Developer Guide Role of the Workflow Starter The workflow starter starts a workflow instance, also referred to as a workflow execution, and can interact with an instance during execution in order to pass additional data to the workflow worker or obtain the current workflow state. The workflow starter uses a workflow client to start the workflow execution, interacts with the workflow as needed during execution, and handles cleanup. The workflow starter could be a locally-run application, a web application, the AWS CLI or even the AWS Management Console. How Amazon SWF Interacts with Your Application Amazon SWF mediates the interaction between the workflow components and maintains a detailed workflow history. Amazon SWF doesn't initiate communication with the components; it waits for HTTP requests from the components and manages the requests as required. For example: • If the request is from a worker, polling for available tasks, Amazon SWF responds directly to the worker if a task is available. For more information about how polling works, see Polling for Tasks in the Amazon Simple Workflow Service Developer Guide. • If the request is a notification from an activity worker that a task is complete, Amazon SWF records the information in the execution history and adds a task to the decision task list to inform the workflow worker that the task is complete, allowing it to proceed to the next step. • If the request is from the workflow worker to execute an activity, Amazon SWF records the information in the execution history and adds a task to the activities task list to direct an activity worker to execute the appropriate activity method. This approach allows workers to run on any system with an Internet connection, including Amazon EC2 instances, corporate data centers, client computers, and so on. They don't even have to be running the same operating system. Because the HTTP requests originate with the workers, there is no need for externally visible ports; workers can run behind a firewall. For More Information For a more thorough discussion of how Amazon SWF works, see Amazon Simple Workflow Service Developer Guide. Role of the Workflow Starter API Version 2021-04-28 40 AWS Flow Framework for Java Developer Guide AWS Flow Framework Basic Concepts: Reliable Execution Asynchronous distributed applications must deal with reliability issues that are not encountered by conventional applications, including: • How to provide reliable communication between
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on. They don't even have to be running the same operating system. Because the HTTP requests originate with the workers, there is no need for externally visible ports; workers can run behind a firewall. For More Information For a more thorough discussion of how Amazon SWF works, see Amazon Simple Workflow Service Developer Guide. Role of the Workflow Starter API Version 2021-04-28 40 AWS Flow Framework for Java Developer Guide AWS Flow Framework Basic Concepts: Reliable Execution Asynchronous distributed applications must deal with reliability issues that are not encountered by conventional applications, including: • How to provide reliable communication between asynchronous distributed components, such as long-running components on remote systems. • How to ensure that results are not lost if a component fails or is disconnected, especially for long- running applications. • How to handle failed distributed components. Applications can rely on the AWS Flow Framework and Amazon SWF to manage these issues. We'll explore how Amazon SWF provides mechanisms to ensure that your workflows operate reliably and in a predictable way, even when they are long-running and depend on asynchronous tasks carried out computationally and with human interaction. Providing Reliable Communication AWS Flow Framework provides reliable communication between a workflow worker and its activities workers by using Amazon SWF to dispatch tasks to distributed activities workers and return the results to the workflow worker. Amazon SWF uses the following methods to ensure reliable communication between a worker and its activities: • Amazon SWF durably stores scheduled activity and workflow tasks and guarantees that they will be performed at most once. • Amazon SWF guarantees that an activity task will either complete successfully and return a valid result or it will notify the workflow worker that the task failed. • Amazon SWF durably stores each completed activity's result or, for failed activities, it stores relevant error information. The AWS Flow Framework then uses the activity results from Amazon SWF to determine how to proceed with the workflow's execution. Reliable Execution API Version 2021-04-28 41 AWS Flow Framework for Java Developer Guide Ensuring that Results are Not Lost Maintaining Workflow History An activity that performs a data-mining operation on a petabyte of data might take hours to complete, and an activity that directs a human worker to perform a complex task might take days, or even weeks to complete! To accommodate scenarios such as these, AWS Flow Framework workflows and activities can take arbitrarily long to complete: up to a limit of one year for a workflow execution. Reliably executing long running processes requires a mechanism to durably store the workflow's execution history on an ongoing basis. The AWS Flow Framework handles this by depending on Amazon SWF, which maintains a running history of each workflow instance. The workflow's history provides a complete and authoritative record of the workflow's progress, including all the workflow and activity tasks that have been scheduled and completed, and the information returned by completed or failed activities. AWS Flow Framework applications usually don't need to interact with the workflow history directly, although they can access it if necessary. For most purposes, applications can simply let the framework interact with the workflow history behind the scenes. For a full discussion of workflow history, see Workflow History in the Amazon Simple Workflow Service Developer Guide. Stateless Execution The execution history allows workflow workers to be stateless. If you have multiple instances of a workflow or activity worker, any worker can perform any task. The worker receives all the state information that it needs to perform the task from Amazon SWF. This approach makes workflows more reliable. For example, if an activity worker fails, you don't have to restart the workflow. Just restart the worker and it will start polling the task list and processing whatever tasks are on the list, regardless of when the failure occurred. You can make your overall workflow fault-tolerant by using two or more workflow and activity workers, perhaps on separate systems. Then, if one of the workers fails, the others will continue to handle scheduled tasks without any interruption in workflow progress. Handling Failed Distributed Components Activities often fail for ephemeral reasons, such as a brief disconnection, so a common strategy for handling failed activities is to retry the activity. Instead of handling the retry process by Ensuring that Results are Not Lost API Version 2021-04-28 42 AWS Flow Framework for Java Developer Guide implementing complex message passing strategies, applications can depend on the AWS Flow Framework. It provides several mechanisms for retrying failed activities, and provides a built-in exception-handling mechanism that works with asynchronous, distributed execution of tasks in a workflow. AWS Flow Framework Basic Concepts: Distributed Execution A workflow instance is essentially a virtual thread of execution that can span activities and orchestration logic running on multiple remote computers. Amazon SWF
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failed activities is to retry the activity. Instead of handling the retry process by Ensuring that Results are Not Lost API Version 2021-04-28 42 AWS Flow Framework for Java Developer Guide implementing complex message passing strategies, applications can depend on the AWS Flow Framework. It provides several mechanisms for retrying failed activities, and provides a built-in exception-handling mechanism that works with asynchronous, distributed execution of tasks in a workflow. AWS Flow Framework Basic Concepts: Distributed Execution A workflow instance is essentially a virtual thread of execution that can span activities and orchestration logic running on multiple remote computers. Amazon SWF and the AWS Flow Framework function as an operating system that manages workflow instances on a virtual CPU by: • Maintaining each instance's execution state. • Switching between instances. • Resuming execution of an instance at the point that it was switched out. Replaying Workflows Because activities can be long-running, it's undesirable to have the workflow simply block until it completes. Instead, the AWS Flow Framework manages workflow execution by using a replay mechanism, which relies on the workflow history maintained by Amazon SWF to execute the workflow in episodes. Each episode replays the workflow logic in a way that executes each activity only once, and ensures that activities and asynchronous methods don't execute until their Promise objects are ready. The workflow starter initiates the first replay episode when it starts the workflow execution. The framework calls the workflow's entry point method and: 1. Executes all workflow tasks that don't depend on activity completion, including calling all activity client methods. 2. Gives Amazon SWF a list of activities tasks to be scheduled for execution. For the first episode, this list consists of only those activities that don't depend on a Promise and can be executed immediately. 3. Notifies Amazon SWF that the episode is complete. Amazon SWF stores the activity tasks in the workflow history and schedules them for execution by placing them on the activity task list. The activity workers poll the task list and execute the tasks. Distributed Execution API Version 2021-04-28 43 AWS Flow Framework for Java Developer Guide When an activity worker completes a task, it returns the result to Amazon SWF, which records it in the workflow execution history and schedules a new workflow task for the workflow worker by placing it on the workflow task list. The workflow worker polls the task list and when it receives the task, it runs the next replay episode, as follows: 1. The framework runs the workflow's entry point method again and: • Executes all workflow tasks that don't depend on activity completion, including calling all activity client methods. However, the framework checks the execution history and doesn't schedule duplicate activity tasks. • Checks the history to see which activity tasks have completed and executes any asynchronous workflow methods that depend on those activities. 2. When all workflow tasks that can be executed have completed, the framework reports back to Amazon SWF: • It gives Amazon SWF a list of any activities whose input Promise<T> objects have become ready since the last episode and can be scheduled for execution. • If the episode generated no additional activity tasks but there are still uncompleted activities, the framework notifies Amazon SWF that the episode is complete. It then waits for another activity to complete, initiating the next replay episode. • If the episode generated no additional activity tasks and all activities have completed, the framework notifies Amazon SWF that the workflow execution is complete. For examples of replay behavior, see AWS Flow Framework for Java Replay Behavior. Replay and Asynchronous Workflow Methods Asynchronous workflow methods are often used much like activities, because the method defers execution until all input Promise<T> objects are ready. However, the replay mechanism handles asynchronous methods differently than activities. • Replay doesn't guarantee that an asynchronous method will execute only once. It defers execution on an asynchronous method until its input Promise objects are ready, but it then executes that method for all subsequent episodes. • When an asynchronous method completes, it doesn't start a new episode. An example of replaying an asynchronous workflow is provided in AWS Flow Framework for Java Replay Behavior. Replay and Asynchronous Workflow Methods API Version 2021-04-28 44 AWS Flow Framework for Java Developer Guide Replay and Workflow Implementation For the most part, you don't need to be concerned with the details of the replay mechanism. It is basically something that happens behind the scenes. However, replay has two important implications for your workflow implementation. • Do not use workflow methods to perform long-running tasks, because replay will repeat that task multiple times. Even asynchronous workflow methods typically run more than once. Instead, use activities for long running tasks; replay executes activities only once. • Your workflow logic must be completely
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Asynchronous Workflow Methods API Version 2021-04-28 44 AWS Flow Framework for Java Developer Guide Replay and Workflow Implementation For the most part, you don't need to be concerned with the details of the replay mechanism. It is basically something that happens behind the scenes. However, replay has two important implications for your workflow implementation. • Do not use workflow methods to perform long-running tasks, because replay will repeat that task multiple times. Even asynchronous workflow methods typically run more than once. Instead, use activities for long running tasks; replay executes activities only once. • Your workflow logic must be completely deterministic; every episode must take the same control flow path. For example, the control flow path should not depend on the current time. For a detailed description of replay and the determinism requirement, see Nondeterminism. AWS Flow Framework Basic Concepts: Task Lists and Task Execution Amazon SWF manages workflow and activity tasks by posting them to named lists. Amazon SWF maintains at least two task lists, one for workflow workers and one for activity workers. Note You can specify as many task lists as you need, with different workers assigned to each list. There is no limit to the number of task lists. You typically specify a worker's task list in the worker host application when you create the worker object. The following excerpt from the HelloWorldWorkflow host application creates a new activity worker and assigns it to the HelloWorldList activities task list. public class GreeterWorker { public static void main(String[] args) throws Exception { ... String domain = " helloWorldExamples"; String taskListToPoll = "HelloWorldList"; ActivityWorker aw = new ActivityWorker(service, domain, taskListToPoll); aw.addActivitiesImplementation(new GreeterActivitiesImpl()); aw.start(); Replay and Workflow Implementation API Version 2021-04-28 45 AWS Flow Framework for Java Developer Guide ... } } By default, Amazon SWF schedules the worker's tasks on the HelloWorldList list. Then the worker polls that list for tasks. You can assign any name to a task list. You can even use the same name for both workflow and activity lists. Internally, Amazon SWF puts workflow and activity task list names in different namespaces, so the two lists will be distinct. If you don't specify a task list, the AWS Flow Framework specifies a default list when the worker registers the type with Amazon SWF. For more information, see Workflow and Activity Type Registration. Sometimes it's useful to have a specific worker or group of workers perform certain tasks. For example, an image processing workflow might use one activity to download an image and another activity to process the image. It's more efficient to perform both tasks on the same system, and avoid the overhead of transferring large files over the network. To support such scenarios, you can explicitly specify a task list when you call an activity client method by using an overload that includes a schedulingOptions parameter. You specify the task list by passing the method an appropriately configured ActivitySchedulingOptions object. For example, suppose that the say activity of the HelloWorldWorkflow application is hosted by an activity worker different from getName and getGreeting. The following example shows how to ensure that say uses the same task list as getName and getGreeting, even if they were originally assigned to different lists. public class GreeterWorkflowImpl implements GreeterWorkflow { private GreeterActivitiesClient operations1 = new GreeterActivitiesClientImpl1(); // getGreeting and getName private GreeterActivitiesClient operations2 = new GreeterActivitiesClientImpl2(); // say @Override public void greet() { Promise<String> name = operations1.getName(); Promise<String> greeting = operations1.getGreeting(name); runSay(greeting); } @Asynchronous private void runSay(Promise<String> greeting){ Task Lists and Task Execution API Version 2021-04-28 46 AWS Flow Framework for Java Developer Guide String taskList = operations1.getSchedulingOptions().getTaskList(); ActivitySchedulingOptions schedulingOptions = new ActivitySchedulingOptions(); schedulingOptions.setTaskList(taskList); operations2.say(greeting, schedulingOptions); } } The asynchronous runSay method gets the getGreeting task list from its client object. Then it creates and configures an ActivitySchedulingOptions object that ensures that say polls the same task list as getGreeting. Note When you pass a schedulingOptions parameter to an activity client method, it overrides the original task list only for that activity execution. If you call the activities client method again without specifying a task list, Amazon SWF assigns the task to the original list, and the activity worker will poll that list. AWS Flow Framework Basic Concepts: Scalable Applications Amazon SWF has two key features that make it easy to scale a workflow application to handle the current load: • A complete workflow execution history, which allows you to implement a stateless application. • Task scheduling that is loosely coupled to task execution, which makes it easy to scale your application to meet current demands. Amazon SWF schedules tasks by posting them to dynamically allocated task lists, not by communicating directly with workflow and activity workers. Instead, the workers use HTTP requests to poll their respective lists for tasks. This approach loosely couples task scheduling to task
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Scalable Applications Amazon SWF has two key features that make it easy to scale a workflow application to handle the current load: • A complete workflow execution history, which allows you to implement a stateless application. • Task scheduling that is loosely coupled to task execution, which makes it easy to scale your application to meet current demands. Amazon SWF schedules tasks by posting them to dynamically allocated task lists, not by communicating directly with workflow and activity workers. Instead, the workers use HTTP requests to poll their respective lists for tasks. This approach loosely couples task scheduling to task execution and allows workers to run on any suitable system, including Amazon EC2 instances, corporate data centers, client computers, and so on. Because the HTTP requests originate with the workers, there is no need for externally visible ports, which enables workers to even run behind a firewall. The long-polling mechanism that workers use to poll for tasks ensures that workers don't get overloaded. Even if there is a spike in scheduled tasks, workers pull tasks at their own pace. Scalable Applications API Version 2021-04-28 47 AWS Flow Framework for Java Developer Guide However, because workers are stateless, you can dynamically scale an application to meet increased load by starting additional worker instances. Even if they are running on different systems, each instance polls the same task list and the first available worker instance executes each task, regardless of where the worker is located or when it started. When the load declines, you can reduce the number of workers accordingly. AWS Flow Framework Basic Concepts: Data Exchange Between Activities and Workflows When you call an asynchronous activity client method, it immediately returns a Promise (also known as a Future) object, which represents the activity method's return value. Initially, the Promise is in an unready state and the return value is undefined. After the activity method completes its task and returns, the framework marshals the return value across the network to the workflow worker, which assigns a value to the Promise and puts the object in a ready state. Even if an activity method has no return value, you can still use the Promise for managing workflow execution. If you pass a returned Promise to an activity client method or an asynchronous workflow method, it defers execution until the object is ready. If you pass one or more Promises to an activity client method, the framework queues the task but defers scheduling it until all the objects are ready. It then extracts the data from each Promise and marshals it across the internet to the activity worker, which passes it to the activity method as a standard type. Note If you need to transfer large amounts of data between workflow and activity workers, the preferred approach is to store the data in a convenient location and just pass the retrieval information. For example, you can store the data in an Amazon S3 bucket and pass the associated URL. The Promise<T> Type The Promise<T> type is similar in some ways to the Java Future<T> type. Both types represent values returned by asynchronous methods and are initially undefined. You access an object's value by calling its get method. Beyond that, the two types behave quite differently. Data Exchange Between Activities and Workflows API Version 2021-04-28 48 AWS Flow Framework for Java Developer Guide • Future<T> is a synchronization construct that allows an application to wait on an asynchronous method's completion. If you call get and the object isn't ready, it blocks until the object is ready. • With Promise<T>, synchronization is handled by the framework. If you call get and the object isn't ready, get throws an exception. The primary purpose of Promise<T> is to manage data flow from one activity to another. It ensures that an activity doesn't execute until the input data is valid. In many cases, workflow workers don't need to access Promise<T> objects directly; they simply pass the objects from one activity to another and let the framework and the activity workers handle the details. To access a Promise<T> object's value in a workflow worker, you must be certain that the object is ready before calling its get method. • The preferred approach is to pass the Promise<T> object to an asynchronous workflow method and process the values there. An asynchronous method defers execution until all of its input Promise<T> objects are ready, which guarantees that you can safely access their values. • Promise<T> exposes an isReady method that returns true if the object is ready. Using isReady to poll a Promise<T> object isn't recommended, but isReady is useful in certain circumstances. The AWS Flow Framework for Java also includes a Settable<T> type, which is derived from Promise<T> and has similar behavior. The difference is that the framework usually sets
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The preferred approach is to pass the Promise<T> object to an asynchronous workflow method and process the values there. An asynchronous method defers execution until all of its input Promise<T> objects are ready, which guarantees that you can safely access their values. • Promise<T> exposes an isReady method that returns true if the object is ready. Using isReady to poll a Promise<T> object isn't recommended, but isReady is useful in certain circumstances. The AWS Flow Framework for Java also includes a Settable<T> type, which is derived from Promise<T> and has similar behavior. The difference is that the framework usually sets the value of a Promise<T> object and the workflow worker is responsible for setting the value of a Settable<T>. There are some circumstance where a workflow worker needs to create a Promise<T> object and set its value. For example, an asynchronous method that returns a Promise<T> object needs to create a return value. • To create an object that represents a typed value, call the static Promise.asPromise method, which creates a Promise<T> object of the appropriate type, sets its value, and puts it in the ready state. • To create a Promise<Void> object, call the static Promise.Void method. The Promise<T> Type API Version 2021-04-28 49 AWS Flow Framework for Java Developer Guide Note Promise<T> can represent any valid type. However, if the data must be marshaled across the internet, the type must be compatible with the data converter. See the next section for details. Data Converters and Marshaling The AWS Flow Framework marshals data across the internet by using a data converter. By default, the framework uses a data converter that is based on the Jackson JSON processor. However, this converter has some limitations. For example, it can't marshal maps that don't use strings as keys. If the default converter isn't sufficient for your application, you can implement a custom data converter. For details, see DataConverters. AWS Flow Framework Basic Concepts: Data Exchange Between Applications and Workflow Executions A workflow entry point method can have one or more parameters, which allows the workflow starter to pass initial data to the workflow. It can also useful to provide additional data to the workflow during execution. For example, if a customer changes their shipping address, you could notify the order-processing workflow so that it can make appropriate changes. Amazon SWF allows workflows to implement a signal method, which allows applications such as the workflow starter to pass data to the workflow at any time. A signal method can have any convenient name and parameters. You designate it as a signal method by including it in your workflow interface definition, and applying a @Signal annotation to the method declaration. The following example shows an order processing workflow interface that declares a signal method, changeOrder, which allows the workflow starter to change the original order after the workflow has started. @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 300) public interface WaitForSignalWorkflow { @Execute(version = "1.0") public void placeOrder(int amount); Data Converters and Marshaling API Version 2021-04-28 50 AWS Flow Framework for Java @Signal public void changeOrder(int amount); } Developer Guide The framework's annotation processor creates a workflow client method with the same name as the signal method and the workflow starter calls the client method to pass data to the workflow. For an example, see AWS Flow Framework Recipes Amazon SWF Timeout Types To ensure that workflow executions run correctly, you can set different types of timeouts with Amazon SWF. Some timeouts specify how long the workflow can run in its entirety. Other timeouts specify how long activity tasks can take before being assigned to a worker and how long they can take to complete from the time they are scheduled. All timeouts in the Amazon SWF API are specified in seconds. Amazon SWF also supports the string NONE as a timeout value, which indicates no timeout. For timeouts related to decision tasks and activity tasks, Amazon SWF adds an event to the workflow execution history. The attributes of the event provide information about what type of timeout occurred and which decision task or activity task was affected. Amazon SWF also schedules a decision task. When the decider receives the new decision task, it will see the timeout event in the history and take an appropriate action by calling the RespondDecisionTaskCompleted action. A task is considered open from the time that it is scheduled until it is closed. Therefore a task is reported as open while a worker is processing it. A task is closed when a worker reports it as completed, canceled, or failed. A task may also be closed by Amazon SWF as the result of a timeout. Timeouts in Workflow and Decision Tasks The following diagram shows how workflow and decision timeouts are related to the lifetime of a workflow: Timeout Types API Version 2021-04-28
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event in the history and take an appropriate action by calling the RespondDecisionTaskCompleted action. A task is considered open from the time that it is scheduled until it is closed. Therefore a task is reported as open while a worker is processing it. A task is closed when a worker reports it as completed, canceled, or failed. A task may also be closed by Amazon SWF as the result of a timeout. Timeouts in Workflow and Decision Tasks The following diagram shows how workflow and decision timeouts are related to the lifetime of a workflow: Timeout Types API Version 2021-04-28 51 AWS Flow Framework for Java Developer Guide There are two timeout types that are relevant to workflow and decision tasks: • Workflow Start to Close (timeoutType: START_TO_CLOSE) – This timeout specifies the maximum time that a workflow execution can take to complete. It is set as a default during workflow registration, but it can be overridden with a different value when the workflow is started. If this timeout is exceeded, Amazon SWF closes the workflow execution and adds an event of type WorkflowExecutionTimedOut to the workflow execution history. In addition to the timeoutType, the event attributes specify the childPolicy that is in effect for this workflow execution. The child policy specifies how child workflow executions are handled if the parent workflow execution times out or otherwise terminates. For example, if the childPolicy is set to TERMINATE, then child workflow executions will be terminated. Once a workflow execution has timed out, you can't take any action on it other than visibility calls. • Decision Task Start to Close (timeoutType: START_TO_CLOSE) – This timeout specifies the maximum time that the corresponding decider can take to complete a decision task. It is set during workflow type registration. If this timeout is exceeded, the task is marked as timed out in the workflow execution history, and Amazon SWF adds an event of type DecisionTaskTimedOut to the workflow history. The event attributes will include the IDs for the events that correspond to when this decision task was scheduled (scheduledEventId) and when it was started (startedEventId). In addition to adding the event, Amazon SWF also schedules a new decision task to alert the decider that this decision task timed out. After this timeout occurs, an attempt to complete the timed-out decision task using RespondDecisionTaskCompleted will fail. Timeouts in Activity Tasks The following diagram shows how timeouts are related to the lifetime of an activity task: Timeouts in Activity Tasks API Version 2021-04-28 52 AWS Flow Framework for Java Developer Guide There are four timeout types that are relevant to activity tasks: • Activity Task Start to Close (timeoutType: START_TO_CLOSE) – This timeout specifies the maximum time that an activity worker can take to process a task after the worker has received the task. Attempts to close a timed out activity task using RespondActivityTaskCanceled, RespondActivityTaskCompleted, and RespondActivityTaskFailed will fail. • Activity Task Heartbeat (timeoutType: HEARTBEAT) – This timeout specifies the maximum time that a task can run before providing its progress through the RecordActivityTaskHeartbeat action. • Activity Task Schedule to Start (timeoutType: SCHEDULE_TO_START) – This timeout specifies how long Amazon SWF waits before timing out the activity task if no workers are available to perform the task. Once timed out, the expired task will not be assigned to another worker. • Activity Task Schedule to Close (timeoutType: SCHEDULE_TO_CLOSE) – This timeout specifies how long the task can take from the time it is scheduled to the time it is complete. As a best practice, this value should not be greater than the sum of the task schedule-to-start timeout and the task start-to-close timeout. Note Each of the timeout types has a default value, which is generally set to NONE (infinite). The maximum time for any activity execution is limited to one year, however. Timeouts in Activity Tasks API Version 2021-04-28 53 AWS Flow Framework for Java Developer Guide You set default values for these during activity type registration, but you can override them with new values when you schedule the activity task. When one of these timeouts occurs, Amazon SWF will add an event of type ActivityTaskTimedOut to the workflow history. The timeoutType value attribute of this event will specify which of these timeouts occurred. For each of the timeouts, the value of timeoutType is shown in parentheses. The event attributes will also include the IDs for the events that correspond to when the activity task was scheduled (scheduledEventId) and when it was started (startedEventId). In addition to adding the event, Amazon SWF also schedules a new decision task to alert the decider that the timeout occurred. Timeouts in Activity Tasks API Version 2021-04-28 54 AWS Flow Framework for Java Developer Guide Understanding a Task in AWS Flow Framework for Java Topics • Task • Order
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this event will specify which of these timeouts occurred. For each of the timeouts, the value of timeoutType is shown in parentheses. The event attributes will also include the IDs for the events that correspond to when the activity task was scheduled (scheduledEventId) and when it was started (startedEventId). In addition to adding the event, Amazon SWF also schedules a new decision task to alert the decider that the timeout occurred. Timeouts in Activity Tasks API Version 2021-04-28 54 AWS Flow Framework for Java Developer Guide Understanding a Task in AWS Flow Framework for Java Topics • Task • Order of Execution • Workflow Execution • Nondeterminism Task The underlying primitive that the AWS Flow Framework for Java uses to manage the execution of asynchronous code is the Task class. An object of type Task represents work that has to be performed asynchronously. When you call an asynchronous method, the framework creates a Task to execute the code in that method and puts it in a list for execution at a later time. Similarly, when you invoke an Activity, a Task is created for it. The method call returns after this, usually returning a Promise<T> as the future result of the call. The Task class is public and may be used directly. For example, we can rewrite the Hello World example to use a Task instead of an asynchronous method. @Override public void startHelloWorld(){ final Promise<String> greeting = client.getName(); new Task(greeting) { @Override protected void doExecute() throws Throwable { client.printGreeting("Hello " + greeting.get() +"!"); } }; } The framework calls the doExecute() method when all the Promises passed to the constructor of the Task become ready. For more details about the Task class, see the AWS SDK for Java documentation. Task API Version 2021-04-28 55 AWS Flow Framework for Java Developer Guide The framework also includes a class called Functor which represents a Task that is also a Promise<T>. The Functor object becomes ready when the Task completes. In the following example, a Functor is created to get the greeting message: Promise<String> greeting = new Functor<String>() { @Override protected Promise<String> doExecute() throws Throwable { return client.getGreeting(); } }; client.printGreeting(greeting); Order of Execution Tasks become eligible for execution only when all Promise<T> typed parameters, passed to the corresponding asynchronous method or activity, become ready. A Task that is ready for execution is logically moved to a ready queue. In other words, it is scheduled for execution. The worker class executes the task by invoking the code that you wrote in the body of the asynchronous method, or by scheduling an activity task in Amazon Simple Workflow Service (AWS) in case of an activity method. As tasks execute and produce results, they cause other tasks to become ready and the execution of the program keeps moving forward. The way the framework executes tasks is important to understand the order in which your asynchronous code executes. Code that appears sequentially in your program may not actually execute in that order. Promise<String> name = getUserName(); printHelloName(name); printHelloWorld(); System.out.println("Hello, Amazon!"); @Asynchronous private Promise<String> getUserName(){ return Promise.asPromise("Bob"); } @Asynchronous private void printHelloName(Promise<String> name){ System.out.println("Hello, " + name.get() + "!"); } Order of Execution API Version 2021-04-28 56 Developer Guide AWS Flow Framework for Java @Asynchronous private void printHelloWorld(){ System.out.println("Hello, World!"); } The code in the listing above will print the following: Hello, Amazon! Hello, World! Hello, Bob This may not be what you expected but can be easily explained by thinking through how the tasks for the asynchronous methods were executed: 1. The call to getUserName creates a Task. Let's call it Task1. Because getUserName doesn't take any parameters, Task1 is immediately put in the ready queue. 2. Next, the call to printHelloName creates a Task that needs to wait for the result of getUserName. Let's call it Task2. Because the requisite value isn't ready yet, Task2 is put in the wait list. 3. Then a task for printHelloWorld is created and added to the ready queue. Let's call it Task3. 4. The println statement then prints "Hello, Amazon!" to the console. 5. At this point, Task1 and Task3 are in the ready queue and Task2 is in the wait list. 6. The worker executes Task1, and its result makes Task2 ready. Task2 gets added to ready queue behind Task3. 7. Task3 and Task2 are then executed in that order. The execution of activities follows the same pattern. When you call a method on the activity client, it creates a Task that, upon execution, schedules an activity in Amazon SWF. The framework relies on features like code generation and dynamic proxies to inject the logic for converting method calls to activity invocations and asynchronous tasks in your program. Workflow Execution The execution of the workflow implementation is also managed by the worker class. When you call
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and its result makes Task2 ready. Task2 gets added to ready queue behind Task3. 7. Task3 and Task2 are then executed in that order. The execution of activities follows the same pattern. When you call a method on the activity client, it creates a Task that, upon execution, schedules an activity in Amazon SWF. The framework relies on features like code generation and dynamic proxies to inject the logic for converting method calls to activity invocations and asynchronous tasks in your program. Workflow Execution The execution of the workflow implementation is also managed by the worker class. When you call a method on the workflow client, it calls Amazon SWF to create a workflow instance. The tasks in Amazon SWF should not be confused with the tasks in the framework. A task in Amazon SWF Workflow Execution API Version 2021-04-28 57 AWS Flow Framework for Java Developer Guide is either an activity task or a decision task. The execution of activity tasks is simple. The activity worker class receives activity tasks from Amazon SWF, invokes the appropriate activity method in your implementation, and returns the result to Amazon SWF. The execution of decision tasks is more involved. The workflow worker receives decision tasks from Amazon SWF. A decision task is effectively a request asking the workflow logic what to do next. The first decision task is generated for a workflow instance when it is started through the workflow client. Upon receiving this decision task, the framework starts executing the code in the workflow method annotated with @Execute. This method executes the coordination logic that schedules activities. When the state of the workflow instance changes—for example, when an activity completes—further decision tasks get scheduled. At this point, the workflow logic can decide to take an action based on the result of the activity; for example, it may decide to schedule another activity. The framework hides all these details from the developer by seamlessly translating decision tasks to the workflow logic. From a developer's point of view, the code looks just like a regular program. Under the covers, the framework maps it to calls to Amazon SWF and decision tasks using the history maintained by Amazon SWF. When a decision task arrives, the framework replays the program execution plugging in the results of the activities completed so far. Asynchronous methods and activities that were waiting for these results get unblocked, and the program execution moves forward. The execution of the example image processing workflow and the corresponding history is shown in the following table. Execution of thumbnail workflow Workflow program execution History maintained by Amazon SWF Initial execution 1. Workflow instance started, id="1" 2. downloadImage scheduled 1. Dispatch loop 2. getImageUrls 3. downloadImage 4. createThumbnail (task in wait queue) 5. uploadImage (task in wait queue) 6. <next iteration of the loop> Workflow Execution API Version 2021-04-28 58 AWS Flow Framework for Java Developer Guide Workflow program execution History maintained by Amazon SWF Replay 1. Dispatch loop 2. getImageUrls 1. Workflow instance started, id="1" 2. downloadImage scheduled 3. downloadImage image path="foo" 3. downloadImage completed, return="foo" 4. createThumbnail 4. createThumbnail scheduled 5. uploadImage (task in wait queue) 6. <next iteration of the loop> Replay 1. Dispatch loop 2. getImageUrls 1. Workflow instance started, id="1" 2. downloadImage scheduled 3. downloadImage image path="foo" 3. downloadImage completed, return="foo" 4. createThumbnail thumbnail path="bar" 4. createThumbnail scheduled 5. uploadImage 5. createThumbnail completed, return="bar" 6. <next iteration of the loop> 6. uploadImage scheduled Replay 1. Dispatch loop 2. getImageUrls 1. Workflow instance started, id="1" 2. downloadImage scheduled 3. downloadImage image path="foo" 3. downloadImage completed, return="foo" 4. createThumbnail thumbnail path="bar" 4. createThumbnail scheduled 5. uploadImage 5. createThumbnail completed, return="bar" 6. <next iteration of the loop> 6. uploadImage scheduled 7. uploadImage completed ... When a call to processImage is made, the framework creates a new workflow instance in Amazon SWF. This is a durable record of the workflow instance being started. The program executes until Workflow Execution API Version 2021-04-28 59 AWS Flow Framework for Java Developer Guide the call to the downloadImage activity, which asks Amazon SWF to schedule an activity. The workflow executes further and creates tasks for subsequent activities, but they can't be executed until the downloadImage activity completes; hence, this episode of replay ends. Amazon SWF dispatches the task for downloadImage activity for execution, and once it is completed, a record is made in the history along with the result. The workflow is now ready to move forward and a decision task is generated by Amazon SWF. The framework receives the decision task and replays the workflow plugging in the result of the downloaded image as recorded in the history. This unblocks the task for createThumbnail, and the execution of the program continues farther by scheduling the createThumbnail activity task in Amazon SWF. The same process repeats for
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hence, this episode of replay ends. Amazon SWF dispatches the task for downloadImage activity for execution, and once it is completed, a record is made in the history along with the result. The workflow is now ready to move forward and a decision task is generated by Amazon SWF. The framework receives the decision task and replays the workflow plugging in the result of the downloaded image as recorded in the history. This unblocks the task for createThumbnail, and the execution of the program continues farther by scheduling the createThumbnail activity task in Amazon SWF. The same process repeats for uploadImage. The execution of the program continues this way until the workflow has processed all images and there are no pending tasks. Because no execution state is stored locally, each decision task may be potentially executed on a different machine. This allows you to easily write programs that are fault tolerant and easily scalable. Nondeterminism Because the framework relies on replay, it is important that the orchestration code (all workflow code with the exception of activity implementations) be deterministic. For example, the control flow in your program should not depend on a random number or the current time. Because these things will change between invocations, the replay may not follow the same path through the orchestration logic. This will lead to unexpected results or errors. The framework provides a WorkflowClock that you can use to get the current time in a deterministic way. See the section on Execution Context for more details. Note Incorrect Spring wiring of workflow implementation objects can also lead to nondeterminism. Workflow implementation beans as well as beans that they depend on must be in the workflow scope (WorkflowScope). For example, wiring a workflow implementation bean to a bean that keeps state and is in the global context will result in unexpected behavior. See the Spring Integration section for more details. Nondeterminism API Version 2021-04-28 60 AWS Flow Framework for Java Developer Guide AWS Flow Framework for Java Programming Guide This section provides details about how to use the features of the AWS Flow Framework for Java to implement workflow applications. Topics • Implementing Workflow Applications with the AWS Flow Framework • Workflow and Activity Contracts • Workflow and Activity Type Registration • Activity and Workflow Clients • Workflow Implementation • Activity Implementation • Implementing AWS Lambda Tasks • Running Programs Written with the AWS Flow Framework for Java • Execution Context • Child Workflow Executions • Continuous Workflows • Setting task priority in Amazon SWF • DataConverters • Passing Data to Asynchronous Methods • Testability and Dependency Injection • Error Handling • Retry Failed Activities • Daemon Tasks • AWS Flow Framework for Java Replay Behavior Implementing Workflow Applications with the AWS Flow Framework The typical steps involved in developing a workflow with the AWS Flow Framework are: Implementing Workflow Applications API Version 2021-04-28 61 AWS Flow Framework for Java Developer Guide 1. Define activity and workflow contracts. Analyze your application's requirements, then determine the required activities and the workflow topology. The activities handle the required processing tasks, while the workflow topology defines the workflow's basic structure and business logic. For example, a media processing application might need to download a file, process it, and then upload the processed file to an Amazon Simple Storage Service (S3) bucket. This can broken down into four activity tasks: 1. download the file from a server 2. process the file (for instance, by transcoding it to a different media format) 3. upload the file to the S3 bucket 4. perform cleanup by deleting the local files This workflow would have an entry point method and would implement a simple linear topology that runs the activities in sequence, much like the HelloWorldWorkflow Application. 2. Implement activity and workflow interfaces. The workflow and activity contracts are defined by Java interfaces, making their calling conventions predictable by SWF, and providing you flexibility when implementing your workflow logic and activity tasks. The various parts of your program can act as consumers of each others' data, yet don't need to be aware of much of the implementation details of any of the other parts. For example, you can define a FileProcessingWorkflow interface and provide different workflow implementations for video encoding, compression, thumbnails, and so on. Each of those workflows can have different control flows and can call different activity methods; your workflow starter doesn't need to know. By using interfaces, it is also simple to test your workflows by using mock implementations that can be replaced later with working code. 3. Generate activity and workflow clients. The AWS Flow Framework eliminates the need for you to implement the details of managing asynchronous execution, sending HTTP requests, marshaling data, and so forth. Instead, the workflow starter executes a workflow instance by calling a method
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provide different workflow implementations for video encoding, compression, thumbnails, and so on. Each of those workflows can have different control flows and can call different activity methods; your workflow starter doesn't need to know. By using interfaces, it is also simple to test your workflows by using mock implementations that can be replaced later with working code. 3. Generate activity and workflow clients. The AWS Flow Framework eliminates the need for you to implement the details of managing asynchronous execution, sending HTTP requests, marshaling data, and so forth. Instead, the workflow starter executes a workflow instance by calling a method on the workflow client, and the workflow implementation executes activities by calling methods on the activities client. The framework handles the details of these interactions in the background. If you are using Eclipse and you have configured your project, like in Setting up the AWS Flow Framework for Java, the AWS Flow Framework annotation processor uses the interface Implementing Workflow Applications API Version 2021-04-28 62 AWS Flow Framework for Java Developer Guide definitions to automatically generate workflow and activities clients that expose the same set of methods as the corresponding interface. 4. Implement activity and workflow host applications. Your workflow and activity implementations must be embedded in host applications that poll Amazon SWF for tasks, marshal any data, and call the appropriate implementation methods. AWS Flow Framework for Java includes WorkflowWorker and ActivityWorker classes that make implementing host applications straightforward and easy to do. 5. Test your workflow. AWS Flow Framework for Java provides JUnit integration that you can use to test your workflows inline and locally. 6. Deploy the workers. You can deploy your workers as appropriate—for example, you can deploy them to Amazon EC2 instances or to computers in your data center. Once deployed and started, the workers start polling Amazon SWF for tasks and handle them as required. 7. Start executions. An application starts a workflow instance by using the workflow client to call the workflow's entry point. You can also start workflows by using the Amazon SWF console. Regardless of how you start a workflow instance, you can use Amazon SWF console to monitor running workflow instance and examine the workflow history for running, completed, and failed instances. The AWS SDK for Java includes a set of AWS Flow Framework for Java samples that you can browse and run by following the instructions in the readme.html file in the root directory. There are also a set of recipes —simple applications — that show how to handle a variety of specific programming issue, which are available from AWS Flow Framework Recipes. Workflow and Activity Contracts Java interfaces are used to declare the signatures of workflows and activities. The interface forms the contract between the implementation of the workflow (or activity) and the client of that workflow (or activity). For example, a workflow type MyWorkflow is defined using an interface that is annotated with the @Workflow annotation: @Workflow @WorkflowRegistrationOptions( defaultExecutionStartToCloseTimeoutSeconds = 60, defaultTaskStartToCloseTimeoutSeconds = 10) public interface MyWorkflow { Workflow and Activity Contracts API Version 2021-04-28 63 AWS Flow Framework for Java Developer Guide @Execute(version = "1.0") void startMyWF(int a, String b); @Signal void signal1(int a, int b, String c); @GetState MyWorkflowState getState(); } The contract has no implementation-specific settings. This use of implementation-neutral contracts allows clients to be decoupled from the implementation and hence provides the flexibility to change the implementation details without breaking the client. Conversely, you may also change the client without necessitating changes to the workflow or activity being consumed. For example, the client may be modified to call an activity asynchronously using promises (Promise<T>) without requiring a change to the activity implementation. Similarly, the activity implementation may be changed so that it is completed asynchronously, for example, by a person sending an email—without requiring the clients of the activity to be changed. In the example above, the workflow interface MyWorkflow contains a method, startMyWF, for starting a new execution. This method is annotated with the @Execute annotation and must have a return type of void or Promise<>. In a given workflow interface, at most one method can be annotated with this annotation. This method is the entry point of the workflow logic, and the framework calls this method to execute the workflow logic when a decision task is received. The workflow interface also defines the signals that may be sent to the workflow. The signal method gets invoked when a signal with a matching name is received by the workflow execution. For example, the MyWorkflow interface declares a signal method, signal1, annotated with the @Signal annotation. The @Signal annotation is required on signal methods. The return type of a signal method must be void. A workflow interface may have zero or more signal methods defined in it. You may declare a workflow interface
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the framework calls this method to execute the workflow logic when a decision task is received. The workflow interface also defines the signals that may be sent to the workflow. The signal method gets invoked when a signal with a matching name is received by the workflow execution. For example, the MyWorkflow interface declares a signal method, signal1, annotated with the @Signal annotation. The @Signal annotation is required on signal methods. The return type of a signal method must be void. A workflow interface may have zero or more signal methods defined in it. You may declare a workflow interface without an @Execute method and some @Signal methods to generate clients that can't start their execution but can send signals to running executions. Methods annotated with @Execute and @Signal annotations may have any number of parameters of any type other than Promise<T> or its derivatives. This allows you to pass strongly typed inputs to a workflow execution at start and while it is running. The return type of the @Execute method must be void or Promise<>. Workflow and Activity Contracts API Version 2021-04-28 64 AWS Flow Framework for Java Developer Guide Additionally, you may also declare a method in the workflow interface to report the latest state of a workflow execution, for instance, the getState method in the previous example. This state isn't the entire application state of the workflow. The intended use of this feature is to allow you to store up to 32 KB of data to indicate the latest status of the execution. For example, in an order processing workflow, you may store a string that indicates that the order has been received, processed, or canceled. This method is called by the framework every time a decision task is completed to get the latest state. The state is stored in Amazon Simple Workflow Service (Amazon SWF) and can be retrieved using the generated external client. This allows you to check the latest state of a workflow execution. Methods annotated with @GetState must not take any arguments and must not have a void return type. You can return any type, which fits your needs, from this method. In the above example, an object of MyWorkflowState (see definition below) is returned by the method that is used to store a string state and a numeric percent complete. The method is expected to perform read-only access of the workflow implementation object and is invoked synchronously, which disallows use of any asynchronous operations like calling methods annotated with @Asynchronous. At most one method in a workflow interface can be annotated with @GetState annotation. public class MyWorkflowState { public String status; public int percentComplete; } Similarly, a set of activities are defined using an interface annotated with @Activities annotation. Each method in the interface corresponds to an activity—for example: @Activities(version = "1.0") @ActivityRegistrationOptions( defaultTaskScheduleToStartTimeoutSeconds = 300, defaultTaskStartToCloseTimeoutSeconds = 3600) public interface MyActivities { // Overrides values from annotation found on the interface @ActivityRegistrationOptions(description = "This is a sample activity", defaultTaskScheduleToStartTimeoutSeconds = 100, defaultTaskStartToCloseTimeoutSeconds = 60) int activity1(); void activity2(int a); } Workflow and Activity Contracts API Version 2021-04-28 65 AWS Flow Framework for Java Developer Guide The interface allows you to group together a set of related activities. You can define any number of activities within an activities interface, and you can define as many activities interfaces as you want. Similar to @Execute and @Signal methods, activity methods can take any number of arguments of any type other than Promise<T> or its derivatives. The return type of an activity must not be Promise<T> or its derivatives. Workflow and Activity Type Registration Amazon SWF requires activity and workflow types to be registered before they can be used. The framework automatically registers the workflows and activities in the implementations you add to the worker. The framework looks for types that implement workflows and activities and registers them with Amazon SWF. By default, the framework uses the interface definitions to infer registration options for workflow and activity types. All workflow interfaces are required to have either the @WorkflowRegistrationOptions annotation or the @SkipRegistration annotation. The workflow worker registers all workflow types it is configured with that have the @WorkflowRegistrationOptions annotation. Similarly, each activity method is required to be annotated with either the @ActivityRegistrationOptions annotation or the @SkipRegistration annotation or one of these annotations must be present on the @Activities interface. The activity worker registers all activity types that it is configured with that an @ActivityRegistrationOptions annotation applies to. The registration is performed automatically when you start one of the workers. Workflow and activity types that have the @SkipRegistration annotation are not registered. @ActivityRegistrationOptions, and @SkipRegistration annotations have override semantics and the most specific one is applied to an activity type. Note that Amazon SWF doesn't allow you to re-register or modify the type once it has
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to be annotated with either the @ActivityRegistrationOptions annotation or the @SkipRegistration annotation or one of these annotations must be present on the @Activities interface. The activity worker registers all activity types that it is configured with that an @ActivityRegistrationOptions annotation applies to. The registration is performed automatically when you start one of the workers. Workflow and activity types that have the @SkipRegistration annotation are not registered. @ActivityRegistrationOptions, and @SkipRegistration annotations have override semantics and the most specific one is applied to an activity type. Note that Amazon SWF doesn't allow you to re-register or modify the type once it has been registered. The framework will try to register all types, but if the type is already registered it will not be re-registered and no error will be reported. If you need to modify registered settings, you must register a new version of the type. You can also override registered settings when starting a new execution or when calling an activity that uses the generated clients. The registration requires a type name and some other registration options. The default implementation determines these as follows: Workflow and Activity Type Registration API Version 2021-04-28 66 AWS Flow Framework for Java Developer Guide Workflow Type Name and Version The framework determines the name of the workflow type from the workflow interface. The form of the default workflow type name is {prefix}{name}. The {prefix} is set to the name of the @Workflow interface followed by a '.' and the {name} is set to the name of the @Execute method. The default name of the workflow type in the preceding example is MyWorkflow.startMyWF. You can override the default name using the name parameter of the @Execute method. The default name of the workflow type in the example is startMyWF. The name must not be an empty string. Note that when you override the name using @Execute, the framework doesn't automatically prepend a prefix to it. You are free to use your own naming scheme. The workflow version is specified using the version parameter of the @Execute annotation. There is no default for version and it must be explicitly specified; versionis a free form string, and you are free to use your own versioning scheme. Signal Name The name of the signal can be specified using the name parameter of the @Signal annotation. If not specified, it is defaulted to the name of the signal method. Activity Type Name and Version The framework determines the name of the activity type from the activities interface. The form of the default activity type name is {prefix}{name}. The {prefix} is set to the name of the @Activities interface followed by a '.' and the {name} is set to the method name. The default {prefix} can be overridden in the @Activities annotation on the activities interface. You can also specify the activity type name using the @Activity annotation on the activity method. Note that when you override the name using @Activity, the framework will not automatically prepend a prefix to it. You are free to user your own naming scheme. The activity version is specified using the version parameter of the @Activities annotation. This version is used as the default for all activities defined in the interface and can be overridden on a per-activity basis using the @Activity annotation. Default Task List The default task list can be configured using the @WorkflowRegistrationOptions and @ActivityRegistrationOptions annotations and setting the defaultTaskList parameter. By default, it is set to USE_WORKER_TASK_LIST. This is a special value that instructs the Workflow Type Name and Version API Version 2021-04-28 67 AWS Flow Framework for Java Developer Guide framework to use the task list that is configured on the worker object that is used to register the activity or workflow type. You can also choose to not register a default task list by setting the default task list to NO_DEFAULT_TASK_LIST using these annotations. This can be used in cases where you want to require that the task list be specified at run time. If no default task list has been registered, then you must specify the task list when starting the workflow or calling the activity method using the StartWorkflowOptions and ActivitySchedulingOptions parameters on the respective method overload of the generated client. Other Registration Options All workflow and activity type registration options that are allowed by the Amazon SWF API can be specified through the framework. For a complete list of workflow registration options, see the following: • @Workflow • @Execute • @WorkflowRegistrationOptions • @Signal For a complete list of activity registration options, see the following: • @Activity • @Activities • @ActivityRegistrationOptions If you want to have complete control over type registration, see Worker Extensibility. Activity and Workflow Clients Workflow and activity clients are generated by the framework based on the @Workflow and @Activities interfaces. Separate client interfaces
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of the generated client. Other Registration Options All workflow and activity type registration options that are allowed by the Amazon SWF API can be specified through the framework. For a complete list of workflow registration options, see the following: • @Workflow • @Execute • @WorkflowRegistrationOptions • @Signal For a complete list of activity registration options, see the following: • @Activity • @Activities • @ActivityRegistrationOptions If you want to have complete control over type registration, see Worker Extensibility. Activity and Workflow Clients Workflow and activity clients are generated by the framework based on the @Workflow and @Activities interfaces. Separate client interfaces are generated that contain methods and settings that make sense only on the client. If you are developing using Eclipse, this is done by the Amazon SWF Eclipse plug-in every time you save the file containing the appropriate interface. The generated code is placed in the generated sources directory in your project in the same package as the interface. Other Registration Options API Version 2021-04-28 68 AWS Flow Framework for Java Developer Guide Note Note that the default directory name used by Eclipse is .apt_generated. Eclipse doesn't show directories whose names start with a '.' in Package Explorer. Use a different directory name if you want to view the generated files in Project Explorer. In Eclipse, right-click the package in Package Explorer, and then choose Properties, Java Compiler, Annotation processing, and modify the Generate source directory setting. Workflow Clients The generated artifacts for the workflow contain three client-side interfaces and the classes that implement them. The generated clients include: • An asynchronous client intended to be consumed from within a workflow implementation that provides asynchronous methods to start workflow executions and send signals • An external client that can be used to start executions and send signals and retrieve workflow state from outside the scope of a workflow implementation • A self client that can be used to create continuous workflows For example, the generated client interfaces for the example MyWorkflow interface are: //Client for use from within a workflow public interface MyWorkflowClient extends WorkflowClient { Promise<Void> startMyWF( int a, String b); Promise<Void> startMyWF( int a, String b, Promise<?>... waitFor); Promise<Void> startMyWF( int a, String b, StartWorkflowOptions optionsOverride, Promise<?>... waitFor); Promise<Void> startMyWF( Promise<Integer> a, Workflow Clients API Version 2021-04-28 69 Developer Guide AWS Flow Framework for Java Promise<String> b); Promise<Void> startMyWF( Promise<Integer> a, Promise<String> b, Promise<?>... waitFor); Promise<Void> startMyWF( Promise<Integer> a, Promise<String> b, StartWorkflowOptions optionsOverride, Promise<?>... waitFor); void signal1( int a, int b, String c); } //External client for use outside workflows public interface MyWorkflowClientExternal extends WorkflowClientExternal { void startMyWF( int a, String b); void startMyWF( int a, String b, StartWorkflowOptions optionsOverride); void signal1( int a, int b, String c); MyWorkflowState getState(); } //self client for creating continuous workflows public interface MyWorkflowSelfClient extends WorkflowSelfClient { void startMyWF( int a, String b); void startMyWF( int a, String b, Promise<?>... waitFor); void startMyWF( Workflow Clients API Version 2021-04-28 70 AWS Flow Framework for Java int a, String b, StartWorkflowOptions optionsOverride, Promise<?>... waitFor); Developer Guide void startMyWF( Promise<Integer> a, Promise<String> b); void startMyWF( Promise<Integer> a, Promise<String> b, Promise<?>... waitFor); void startMyWF( Promise<Integer> a, Promise<String> b, StartWorkflowOptions optionsOverride, Promise<?>... waitFor); The interfaces have overloaded methods corresponding to each method in the @Workflow interface that you declared. The external client mirrors the methods on the @Workflow interface with one additional overload of the @Execute method that takes StartWorkflowOptions. You can use this overload to pass additional options when starting a new workflow execution. These options allow you to override the default task list, timeout settings, and associate tags with the workflow execution. On the other hand, the asynchronous client has methods that allow asynchronous invocation of the @Execute method. The following method overloads are generated in the client interface for the @Execute method in the workflow interface: 1. An overload that takes the original arguments as is. The return type of this overload will be Promise<Void> if the original method returned void; otherwise, it will be the Promise<> as declared on the original method. For example: Original method: void startMyWF(int a, String b); Generated method: Workflow Clients API Version 2021-04-28 71 AWS Flow Framework for Java Developer Guide Promise<Void> startMyWF(int a, String b); This overload should be used when all the arguments of the workflow are available and don't need to be waited for. 2. An overload that takes the original arguments as is and additional variable arguments of type Promise<?>. The return type of this overload will be Promise<Void> if the original method returned void; otherwise, it will be the Promise<> as declared on the original method. For example: Original method: void startMyWF(int a, String b); Generated method: Promise<void> startMyWF(int a, String b, Promise<?>...waitFor); This overload should be used when all the arguments of the workflow are available and don't need to be waited
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should be used when all the arguments of the workflow are available and don't need to be waited for. 2. An overload that takes the original arguments as is and additional variable arguments of type Promise<?>. The return type of this overload will be Promise<Void> if the original method returned void; otherwise, it will be the Promise<> as declared on the original method. For example: Original method: void startMyWF(int a, String b); Generated method: Promise<void> startMyWF(int a, String b, Promise<?>...waitFor); This overload should be used when all the arguments of the workflow are available and don't need to be waited for, but you want to wait for some other promises to become ready. The variable argument can be used to pass such Promise<?> objects that were not declared as arguments, but you want to wait for before executing the call. 3. An overload that takes the original arguments as is, an additional argument of type StartWorkflowOptions and additional variable arguments of type Promise<?>. The return type of this overload will be Promise<Void> if the original method returned void; otherwise, it will be the Promise<> as declared on the original method. For example: Original method: void startMyWF(int a, String b); Generated method: Promise<void> startMyWF( int a, String b, StartWorkflowOptions optionOverrides, Workflow Clients API Version 2021-04-28 72 AWS Flow Framework for Java Developer Guide Promise<?>...waitFor); This overload should be used when all the arguments of the workflow are available and don't need to be waited for, when you want to override default settings used to start the workflow execution, or when you want to wait for some other promises to become ready. The variable argument can be used to pass such Promise<?> objects that were not declared as arguments, but you want to wait for before executing the call. 4. An overload with each argument in the original method replaced with a Promise<> wrapper. The return type of this overload will be Promise<Void> if the original method returned void; otherwise, it will be the Promise<> as declared on the original method. For example: Original method: void startMyWF(int a, String b); Generated method: Promise<Void> startMyWF( Promise<Integer> a, Promise<String> b); This overload should be used when the arguments to be passed to the workflow execution are to be evaluated asynchronously. A call to this method overload will not execute until all arguments passed to it become ready. If some of the arguments are already ready, then convert them to a Promise that is already in ready state through the Promise.asPromise(value) method. For example: Promise<Integer> a = getA(); String b = getB(); startMyWF(a, Promise.asPromise(b)); 5. An overload with each argument in the original method is replaced with a Promise<> wrapper. The overload also has additional variable arguments of type Promise<?>. The return type of this overload will be Promise<Void> if the original method returned void; otherwise, it will be the Promise<> as declared on the original method. For example: Original method: Workflow Clients API Version 2021-04-28 73 AWS Flow Framework for Java Developer Guide void startMyWF(int a, String b); Generated method: Promise<Void> startMyWF( Promise<Integer> a, Promise<String> b, Promise<?>...waitFor); This overload should be used when the arguments to be passed to the workflow execution are to be evaluated asynchronously and you want to wait for some other promises to become ready as well. A call to this method overload will not execute until all arguments passed to it become ready. 6. An overload with each argument in the original method replaced with a Promise<?> wrapper. The overload also has an additional argument of type StartWorkflowOptions and variable arguments of type Promise<?>. The return type of this overload will be Promise<Void> if the original method returned void; otherwise, it will be the Promise<> as declared on the original method. For example: Original method: void startMyWF(int a, String b); Generated method: Promise<Void> startMyWF( Promise<Integer> a, Promise<String> b, StartWorkflowOptions optionOverrides, Promise<?>...waitFor); Use this overload when the arguments to be passed to the workflow execution will be evaluated asynchronously and you want to override default settings used to start the workflow execution. A call to this method overload will not execute until all arguments passed to it become ready. A method is also generated corresponding to each signal in the workflow interface—for example: Workflow Clients API Version 2021-04-28 74 AWS Flow Framework for Java Original method: void signal1(int a, int b, String c); Generated method: void signal1(int a, int b, String c); Developer Guide The asynchronous client doesn't contain a method corresponding to the method annotated with @GetState in the original interface. Because retrieval of state requires a web service call, it is not suitable for use within a workflow. Hence, it is provided only through the external client. The self client is intended to be used from within a workflow to start a new execution on completion of the
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workflow interface—for example: Workflow Clients API Version 2021-04-28 74 AWS Flow Framework for Java Original method: void signal1(int a, int b, String c); Generated method: void signal1(int a, int b, String c); Developer Guide The asynchronous client doesn't contain a method corresponding to the method annotated with @GetState in the original interface. Because retrieval of state requires a web service call, it is not suitable for use within a workflow. Hence, it is provided only through the external client. The self client is intended to be used from within a workflow to start a new execution on completion of the current execution. The methods on this client are similar to the ones on the asynchronous client, but return void. This client doesn't have methods corresponding to methods annotated with @Signal and @GetState. For more details, see the Continuous Workflows. The generated clients derive from base interfaces: WorkflowClient and WorkflowClientExternal, respectively, which provide methods that you can use to cancel or terminate the workflow execution. For more details about these interfaces, see the AWS SDK for Java documentation. The generated clients allow you to interact with workflow executions in a strongly typed fashion. Once created, an instance of a generated client is tied to a specific workflow execution and can be used only for that execution. In addition, the framework also provides dynamic clients that are not specific to a workflow type or execution. The generated clients rely on this client under the covers. You may also directly use these clients. See the section on Dynamic Clients. The framework also generates factories for creating the strongly typed clients. The generated client factories for the example MyWorkflow interface are: //Factory for clients to be used from within a workflow public interface MyWorkflowClientFactory extends WorkflowClientFactory<MyWorkflowClient> { } //Factory for clients to be used outside the scope of a workflow public interface MyWorkflowClientExternalFactory { Workflow Clients API Version 2021-04-28 75 AWS Flow Framework for Java Developer Guide GenericWorkflowClientExternal getGenericClient(); void setGenericClient(GenericWorkflowClientExternal genericClient); DataConverter getDataConverter(); void setDataConverter(DataConverter dataConverter); StartWorkflowOptions getStartWorkflowOptions(); void setStartWorkflowOptions(StartWorkflowOptions startWorkflowOptions); MyWorkflowClientExternal getClient(); MyWorkflowClientExternal getClient(String workflowId); MyWorkflowClientExternal getClient(WorkflowExecution workflowExecution); MyWorkflowClientExternal getClient( WorkflowExecution workflowExecution, GenericWorkflowClientExternal genericClient, DataConverter dataConverter, StartWorkflowOptions options); } The WorkflowClientFactory base interface is: public interface WorkflowClientFactory<T> { GenericWorkflowClient getGenericClient(); void setGenericClient(GenericWorkflowClient genericClient); DataConverter getDataConverter(); void setDataConverter(DataConverter dataConverter); StartWorkflowOptions getStartWorkflowOptions(); void setStartWorkflowOptions(StartWorkflowOptions startWorkflowOptions); T getClient(); T getClient(String workflowId); T getClient(WorkflowExecution execution); T getClient(WorkflowExecution execution, StartWorkflowOptions options); T getClient(WorkflowExecution execution, StartWorkflowOptions options, DataConverter dataConverter); } You should use these factories to create instances of the client. The factory allows you to configure the generic client (the generic client should be used for providing custom client implementation) and the DataConverter used by the client to marshal data, as well as the options used to start the workflow execution. For more details, see the DataConverters and Child Workflow Executions sections. The StartWorkflowOptions contains settings that you can use to override the defaults—for example, timeouts—specified at registration time. For more details about the StartWorkflowOptions class, see the AWS SDK for Java documentation. Workflow Clients API Version 2021-04-28 76 AWS Flow Framework for Java Developer Guide The external client can be used to start workflow executions from outside of the scope of a workflow while the asynchronous client can be used to start a workflow execution from code within a workflow. In order to start an execution, you simply use the generated client to call the method that corresponds to the method annotated with @Execute in the workflow interface. The framework also generates implementation classes for the client interfaces. These clients create and send requests to Amazon SWF to perform the appropriate action. The client version of the @Execute method either starts a new workflow execution or creates a child workflow execution using Amazon SWF APIs. Similarly, the client version of the @Signal method uses Amazon SWF APIs to send a signal. Note The external workflow client must be configured with the Amazon SWF client and domain. You can either use the client factory constructor that takes these as parameters or pass in a generic client implementation that is already configured with the Amazon SWF client and domain. The framework walks the type hierarchy of the workflow interface and also generates client interfaces for parent workflow interfaces and derives from them. Activity Clients Similar to the workflow client, a client is generated for each interface annotated with @Activities. The generated artifacts include a client side interface and a client class. The generated interface for the example @Activities interface above (MyActivities) is as follows: public interface MyActivitiesClient extends ActivitiesClient { Promise<Integer> activity1(); Promise<Integer> activity1(Promise<?>... waitFor); Promise<Integer> activity1(ActivitySchedulingOptions optionsOverride, Promise<?>... waitFor); Promise<Void> activity2(int a); Promise<Void> activity2(int a, Promise<?>... waitFor); Promise<Void> activity2(int a, ActivitySchedulingOptions optionsOverride, Promise<?>... waitFor); Promise<Void> activity2(Promise<Integer> a); Activity Clients API Version 2021-04-28 77 AWS Flow Framework for Java Developer Guide Promise<Void> activity2(Promise<Integer> a, Promise<?>... waitFor); Promise<Void> activity2(Promise<Integer>
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and derives from them. Activity Clients Similar to the workflow client, a client is generated for each interface annotated with @Activities. The generated artifacts include a client side interface and a client class. The generated interface for the example @Activities interface above (MyActivities) is as follows: public interface MyActivitiesClient extends ActivitiesClient { Promise<Integer> activity1(); Promise<Integer> activity1(Promise<?>... waitFor); Promise<Integer> activity1(ActivitySchedulingOptions optionsOverride, Promise<?>... waitFor); Promise<Void> activity2(int a); Promise<Void> activity2(int a, Promise<?>... waitFor); Promise<Void> activity2(int a, ActivitySchedulingOptions optionsOverride, Promise<?>... waitFor); Promise<Void> activity2(Promise<Integer> a); Activity Clients API Version 2021-04-28 77 AWS Flow Framework for Java Developer Guide Promise<Void> activity2(Promise<Integer> a, Promise<?>... waitFor); Promise<Void> activity2(Promise<Integer> a, ActivitySchedulingOptions optionsOverride, Promise<?>... waitFor); } The interface contains a set of overloaded methods corresponding to each activity method in the @Activities interface. These overloads are provided for convenience and allow calling activities asynchronously. For each activity method in the @Activities interface, the following method overloads are generated in the client interface: 1. An overload that takes the original arguments as is. The return type of this overload is Promise<T>, where T is the return type of the original method. For example: Original method: void activity2(int foo); Generated method: Promise<Void> activity2(int foo); This overload should be used when all the arguments of the workflow are available and don't need to be waited for. 2. An overload that takes the original arguments as is, an argument of type ActivitySchedulingOptions and additional variable arguments of type Promise<?>. The return type of this overload is Promise<T>, where T is the return type of the original method. For example: Original method: void activity2(int foo); Generated method: Promise<Void> activity2( int foo, ActivitySchedulingOptions optionsOverride, Activity Clients API Version 2021-04-28 78 AWS Flow Framework for Java Developer Guide Promise<?>... waitFor); This overload should be used when all the arguments of the workflow are available and don't need to be waited for, when you want to override the default settings, or when you want to wait for additional Promises to become ready. The variable arguments can be used to pass such additional Promise<?> objects that were not declared as arguments, but you want to wait for before executing the call. 3. An overload with each argument in the original method replaced with a Promise<> wrapper. The return type of this overload is Promise<T>, where T is the return type of the original method. For example: Original method: void activity2(int foo); Generated method: Promise<Void> activity2(Promise<Integer> foo); This overload should be used when the arguments to be passed to the activity will be evaluated asynchronously. A call to this method overload will not execute until all arguments passed to it become ready. 4. An overload with each argument in the original method replaced with a Promise<> wrapper. The overload also has an additional argument of type ActivitySchedulingOptions and variable arguments of type Promise<?>. The return type of this overload is Promise<T>, where T is the return type of the original method. For example: Original method: void activity2(int foo); Generated method: Promise<Void> activity2( Promise<Integer> foo, ActivitySchedulingOptions optionsOverride, Promise<?>...waitFor); Activity Clients API Version 2021-04-28 79 AWS Flow Framework for Java Developer Guide This overload should be used when the arguments to be passed to the activity will be evaluated asynchronously, when you want to override the default settings registered with the type, or when you want to wait for additional Promises to become ready. A call to this method overload will not execute until all arguments passed to it become ready. The generated client class implements this interface. The implementation of each interface method creates and sends a request to Amazon SWF to schedule an activity task of the appropriate type using Amazon SWF APIs. 5. An overload that takes the original arguments as is and additional variable arguments of type Promise<?>. The return type of this overload is Promise<T>, where T is the return type of the original method. For example: Original method: void activity2(int foo); Generated method: Promise< Void > activity2(int foo, Promise<?>...waitFor); This overload should be used when all the activity's arguments are available and don't need to be waited for, but you want to wait for other Promise objects to become ready. 6. An overload with each argument in the original method replaced with a Promise wrapper and additional variable arguments of type Promise<?>. The return type of this overload is Promise<T>, where T is the return type of the original method. For example: Original method: void activity2(int foo); Generated method: Promise<Void> activity2( Promise<Integer> foo, Promise<?>... waitFor); Activity Clients API Version 2021-04-28 80 AWS Flow Framework for Java Developer Guide This overload should be used when all the arguments of the activity will be waited for asynchronously and you also want to wait for some other Promises to become ready. A call to this method overload will execute asynchronously when all Promise objects passed become ready. The generated
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additional variable arguments of type Promise<?>. The return type of this overload is Promise<T>, where T is the return type of the original method. For example: Original method: void activity2(int foo); Generated method: Promise<Void> activity2( Promise<Integer> foo, Promise<?>... waitFor); Activity Clients API Version 2021-04-28 80 AWS Flow Framework for Java Developer Guide This overload should be used when all the arguments of the activity will be waited for asynchronously and you also want to wait for some other Promises to become ready. A call to this method overload will execute asynchronously when all Promise objects passed become ready. The generated activity client also has a protected method corresponding to each activity method, named {activity method name}Impl(), that all activity overloads call into. You can override this method to create mock client implementations. This method takes as arguments: all the arguments to the original method in Promise<> wrappers, ActivitySchedulingOptions, and variable arguments of type Promise<?>. For example: Original method: void activity2(int foo); Generated method: Promise<Void> activity2Impl( Promise<Integer> foo, ActivitySchedulingOptions optionsOverride, Promise<?>...waitFor); Scheduling Options The generated activity client allows you to pass in ActivitySchedulingOptions as an argument. The ActivitySchedulingOptions structure contains settings that determine the configuration of the activity task that the framework schedules in Amazon SWF. These settings override the defaults that are specified as registration options. To specify scheduling options dynamically, create an ActivitySchedulingOptions object, configure it as desired, and pass it to the activity method. In the following example, we have specified the task list that should be used for the activity task. This will override the default registered task list for this invocation of the activity. public class OrderProcessingWorkflowImpl implements OrderProcessingWorkflow { OrderProcessingActivitiesClient activitiesClient = new OrderProcessingActivitiesClientImpl(); Scheduling Options API Version 2021-04-28 81 AWS Flow Framework for Java Developer Guide // Workflow entry point @Override public void processOrder(Order order) { Promise<Void> paymentProcessed = activitiesClient.processPayment(order); ActivitySchedulingOptions schedulingOptions = new ActivitySchedulingOptions(); if (order.getLocation() == "Japan") { schedulingOptions.setTaskList("TasklistAsia"); } else { schedulingOptions.setTaskList("TasklistNorthAmerica"); } activitiesClient.shipOrder(order, schedulingOptions, paymentProcessed); } } Dynamic Clients In addition to the generated clients, the framework also provides general purpose clients —DynamicWorkflowClient and DynamicActivityClient—that you can use to dynamically start workflow executions, send signals, schedule activities, etc. For instance, you may want to schedule an activity whose type isn't known at design time. You can use the DynamicActivityClient for scheduling such an activity task. Similarly, you can dynamically schedule a child workflow execution by using the DynamicWorkflowClient. In the following example, the workflow looks up the activity from a database and uses the dynamic activity client to schedule it: //Workflow entrypoint @Override public void start() { MyActivitiesClient client = new MyActivitiesClientImpl(); Promise<ActivityType> activityType = client.lookUpActivityFromDB(); Promise<String> input = client.getInput(activityType); scheduleDynamicActivity(activityType, input); } @Asynchronous void scheduleDynamicActivity(Promise<ActivityType> type, Promise<String> input){ Dynamic Clients API Version 2021-04-28 82 AWS Flow Framework for Java Developer Guide Promise<?>[] args = new Promise<?>[1]; args[0] = input; DynamicActivitiesClient activityClient = new DynamicActivitiesClientImpl(); activityClient.scheduleActivity(type.get(), args, null, Void.class); } For more details, see the AWS SDK for Java documentation. Signaling and Canceling Workflow Executions The generated workflow client has methods corresponding to each signal that can be sent to the workflow. You can use them from within a workflow to send signals to other workflow executions. This provides a typed mechanism for sending signals. However, sometimes you may need to dynamically determine the signal name—for example, when the signal name is received in a message. You can use the dynamic workflow client to dynamically send signals to any workflow execution. Similarly, you can use the client to request cancellation of another workflow execution. In the following example, the workflow looks up the execution to send a signal to from a database and sends the signal dynamically using the dynamic workflow client. //Workflow entrypoint public void start() { MyActivitiesClient client = new MyActivitiesClientImpl(); Promise<WorkflowExecution> execution = client.lookUpExecutionInDB(); Promise<String> signalName = client.getSignalToSend(); Promise<String> input = client.getInput(signalName); sendDynamicSignal(execution, signalName, input); } @Asynchronous void sendDynamicSignal( Promise<WorkflowExecution> execution, Promise<String> signalName, Promise<String> input) { DynamicWorkflowClient workflowClient = new DynamicWorkflowClientImpl(execution.get()); Dynamic Clients API Version 2021-04-28 83 AWS Flow Framework for Java Developer Guide Object[] args = new Promise<?>[1]; args[0] = input.get(); workflowClient.signalWorkflowExecution(signalName.get(), args); } Workflow Implementation In order to implement a workflow, you write a class that implements the desired @Workflow interface. For instance, the example workflow interface (MyWorkflow) can be implemented like so: public class MyWFImpl implements MyWorkflow { MyActivitiesClient client = new MyActivitiesClientImpl(); @Override public void startMyWF(int a, String b){ Promise<Integer> result = client.activity1(); client.activity2(result); } @Override public void signal1(int a, int b, String c){ //Process signal client.activity2(a + b); } } The @Execute method in this class is the entry point of the workflow logic. Because the framework uses replay to reconstruct the object state when a decision task is to be processed, a new object is created for each decision task. The use of Promise<T> as a parameter is disallowed in the
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workflow interface (MyWorkflow) can be implemented like so: public class MyWFImpl implements MyWorkflow { MyActivitiesClient client = new MyActivitiesClientImpl(); @Override public void startMyWF(int a, String b){ Promise<Integer> result = client.activity1(); client.activity2(result); } @Override public void signal1(int a, int b, String c){ //Process signal client.activity2(a + b); } } The @Execute method in this class is the entry point of the workflow logic. Because the framework uses replay to reconstruct the object state when a decision task is to be processed, a new object is created for each decision task. The use of Promise<T> as a parameter is disallowed in the @Execute method within a @Workflow interface. This is done because making an asynchronous call is purely a decision of the caller. The workflow implementation itself doesn't depend on whether the invocation was synchronous or asynchronous. Therefore, the generated client interface has overloads that take Promise<T> parameters so that these methods can be called asynchronously. The return type of an @Execute method can only be void or Promise<T>. Note that a return type of the corresponding external client is void and not Promise<>. Because the external client isn't intended to be used from the asynchronous code, the external client doesn't return Promise objects. For getting results of workflow executions stated externally, you can design the workflow to update state in an external data store through an activity. Amazon SWF's visibility APIs can also Workflow Implementation API Version 2021-04-28 84 AWS Flow Framework for Java Developer Guide be used to retrieve the result of a workflow for diagnostic purposes. It isn't recommended that you use the visibility APIs to retrieve results of workflow executions as a general practice because these API calls may get throttled by Amazon SWF. The visibility APIs require you to identify the workflow execution using a WorkflowExecution structure. You can get this structure from the generated workflow client by calling the getWorkflowExecution method. This method will return the WorkflowExecution structure corresponding to the workflow execution that the client is bound to. See the Amazon Simple Workflow Service API Reference for more details about the visibility APIs. When calling activities from your workflow implementation, you should use the generated activities client. Similarly, to send signals, use the generated workflow clients. Decision Context The framework provides an ambient context anytime workflow code is executed by the framework. This context provides context-specific functionality that you may access in your workflow implementation, such as creating a timer. See the section on Execution Context for more information. Exposing Execution State Amazon SWF allows you to add custom state in the workflow history. The latest state reported by the workflow execution is returned to you through visibility calls to the Amazon SWF service and in the Amazon SWF console. For example, in an order processing workflow, you may report the order status at different stages like 'order received', 'order shipped', and so on. In the AWS Flow Framework for Java, this is accomplished through a method on your workflow interface that is annotated with the @GetState annotation. When the decider is done processing a decision task, it calls this method to get the latest state from the workflow implementation. Besides visibility calls, the state can also be retrieved using the generated external client (which uses the visibility API calls internally). The following example demonstrates how to set the execution context. @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 60, defaultTaskStartToCloseTimeoutSeconds = 10) public interface PeriodicWorkflow { @Execute(version = "1.0") void periodicWorkflow(); Decision Context API Version 2021-04-28 85 AWS Flow Framework for Java Developer Guide @GetState String getState(); } @Activities(version = "1.0") @ActivityRegistrationOptions(defaultTaskScheduleToStartTimeoutSeconds = 300, defaultTaskStartToCloseTimeoutSeconds = 3600) public interface PeriodicActivity { void activity1(); } public class PeriodicWorkflowImpl implements PeriodicWorkflow { private DecisionContextProvider contextProvider = new DecisionContextProviderImpl(); private WorkflowClock clock = contextProvider.getDecisionContext().getWorkflowClock(); private PeriodicActivityClient activityClient = new PeriodicActivityClientImpl(); private String state; @Override public void periodicWorkflow() { state = "Just Started"; callPeriodicActivity(0); } @Asynchronous private void callPeriodicActivity(int count, Promise<?>... waitFor) { if(count == 100) { state = "Finished Processing"; return; } // call activity activityClient.activity1(); Exposing Execution State API Version 2021-04-28 86 AWS Flow Framework for Java Developer Guide // Repeat the activity after 1 hour. Promise<Void> timer = clock.createTimer(3600); state = "Waiting for timer to fire. Count = "+count; callPeriodicActivity(count+1, timer); } @Override public String getState() { return state; } } public class PeriodicActivityImpl implements PeriodicActivity { @Override public static void activity1() { ... } } The generated external client can be used to retrieve the latest state of the workflow execution at any time. PeriodicWorkflowClientExternal client = new PeriodicWorkflowClientExternalFactoryImpl().getClient(); System.out.println(client.getState()); In the above example, the execution state is reported at various stages. When the workflow instance starts, periodicWorkflow reports the initial state as 'Just Started'. Each call to callPeriodicActivity then updates the workflow state. Once activity1 has been called 100 times, the method returns and the workflow instance completes.
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timer); } @Override public String getState() { return state; } } public class PeriodicActivityImpl implements PeriodicActivity { @Override public static void activity1() { ... } } The generated external client can be used to retrieve the latest state of the workflow execution at any time. PeriodicWorkflowClientExternal client = new PeriodicWorkflowClientExternalFactoryImpl().getClient(); System.out.println(client.getState()); In the above example, the execution state is reported at various stages. When the workflow instance starts, periodicWorkflow reports the initial state as 'Just Started'. Each call to callPeriodicActivity then updates the workflow state. Once activity1 has been called 100 times, the method returns and the workflow instance completes. Workflow Locals Sometimes, you may have a need for the use of static variables in your workflow implementation. For example, you may want to store a counter that is to be accessed from various places (possibly different classes) in the implementation of the workflow. However, you can't rely on static variables in your workflows because static variables are shared across threads, which is problematic because a worker may process different decision tasks on different threads at the same time. Workflow Locals API Version 2021-04-28 87 AWS Flow Framework for Java Developer Guide Alternatively, you may store such state in a field on the workflow implementation, but then you will need to pass the implementation object around. To address this need, the framework provides a WorkflowExecutionLocal<?> class. Any state that needs to have static variable like semantics should be kept as an instance local using WorkflowExecutionLocal<?>. You can declare and use a static variable of this type. For example, in the following snippet, a WorkflowExecutionLocal<String> is used to store a user name. public class MyWFImpl implements MyWF { public static WorkflowExecutionLocal<String> username = new WorkflowExecutionLocal<String>(); @Override public void start(String username){ this.username.set(username); Processor p = new Processor(); p.updateLastLogin(); p.greetUser(); } public static WorkflowExecutionLocal<String> getUsername() { return username; } public static void setUsername(WorkflowExecutionLocal<String> username) { MyWFImpl.username = username; } } public class Processor { void updateLastLogin(){ UserActivitiesClient c = new UserActivitiesClientImpl(); c.refreshLastLogin(MyWFImpl.getUsername().get()); } void greetUser(){ GreetingActivitiesClient c = new GreetingActivitiesClientImpl(); c.greetUser(MyWFImpl.getUsername().get()); } } Workflow Locals API Version 2021-04-28 88 AWS Flow Framework for Java Developer Guide Activity Implementation Activities are implemented by providing an implementation of the @Activities interface. The AWS Flow Framework for Java uses the activity implementation instances configured on the worker to process activity tasks at run time. The worker automatically looks up the activity implementation of the appropriate type. You can use properties and fields to pass resources to activity instances, such as database connections. Because the activity implementation object may be accessed from multiple threads, shared resources must be thread safe. Note that the activity implementation doesn't take parameters of type Promise<> or return objects of that type. This is because the implementation of the activity should not depend on how it was invoked (synchronously or asynchronously). The activities interface shown before can be implemented like this: public class MyActivitiesImpl implements MyActivities { @Override @ManualActivityCompletion public int activity1(){ //implementation } @Override public void activity2(int foo){ //implementation } } A thread local context is available to the activity implementation that can be used to retrieve the task object, data converter object being used, etc. The current context can be accessed through ActivityExecutionContextProvider.getActivityExecutionContext(). For more details, see the AWS SDK for Java documentation for ActivityExecutionContext and the section Execution Context. Manually Completing Activities The @ManualActivityCompletion annotation in the example above is an optional annotation. It is allowed only on methods that implement an activity and is used to configure the activity to Activity Implementation API Version 2021-04-28 89 AWS Flow Framework for Java Developer Guide not automatically complete when the activity method returns. This could be useful when you want to complete the activity asynchronously—for example, manually after a human action has been completed. By default, the framework considers the activity completed when your activity method returns. This means that the activity worker reports activity task completion to Amazon SWF and provides it with the results (if any). However, there are use cases where you don't want the activity task to be marked completed when the activity method returns. This is especially useful when you are modeling human tasks. For example, the activity method may send an email to a person who must complete some work before the activity task is completed. In such cases, you can annotate the activity method with @ManualActivityCompletion annotation to tell the activity worker that it should not complete the activity automatically. In order to complete the activity manually, you can either use the ManualActivityCompletionClient provided in the framework or use the RespondActivityTaskCompleted method on the Amazon SWF Java client provided in the Amazon SWF SDK. For more details, see the AWS SDK for Java documentation. In order to complete the activity task, you need to provide a task token. The task token is used
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person who must complete some work before the activity task is completed. In such cases, you can annotate the activity method with @ManualActivityCompletion annotation to tell the activity worker that it should not complete the activity automatically. In order to complete the activity manually, you can either use the ManualActivityCompletionClient provided in the framework or use the RespondActivityTaskCompleted method on the Amazon SWF Java client provided in the Amazon SWF SDK. For more details, see the AWS SDK for Java documentation. In order to complete the activity task, you need to provide a task token. The task token is used by Amazon SWF to uniquely identify tasks. You can access this token from the ActivityExecutionContext in your activity implementation. You must pass this token to the party that is responsible for completing the task. This token can be retrieved from the ActivityExecutionContext by calling ActivityExecutionContextProvider.getActivityExecutionContext().getTaskToken(). The getName activity of the Hello World example can be implemented to send an email asking someone to provide a greeting message: @ManualActivityCompletion @Override public String getName() throws InterruptedException { ActivityExecutionContext executionContext = contextProvider.getActivityExecutionContext(); String taskToken = executionContext.getTaskToken(); sendEmail("[email protected]", "Please provide a name for the greeting message and close task with token: " + taskToken); return "This will not be returned to the caller"; } The following code snippet can be used to provide the greeting and close the task by using the ManualActivityCompletionClient. Alternatively, you can also fail the task: Manually Completing Activities API Version 2021-04-28 90 AWS Flow Framework for Java Developer Guide public class CompleteActivityTask { public void completeGetNameActivity(String taskToken) { AmazonSimpleWorkflow swfClient = new AmazonSimpleWorkflowClient(...); // use AWS access keys ManualActivityCompletionClientFactory manualCompletionClientFactory = new ManualActivityCompletionClientFactoryImpl(swfClient); ManualActivityCompletionClient manualCompletionClient = manualCompletionClientFactory.getClient(taskToken); String result = "Hello World!"; manualCompletionClient.complete(result); } public void failGetNameActivity(String taskToken, Throwable failure) { AmazonSimpleWorkflow swfClient = new AmazonSimpleWorkflowClient(...); // use AWS access keys ManualActivityCompletionClientFactory manualCompletionClientFactory = new ManualActivityCompletionClientFactoryImpl(swfClient); ManualActivityCompletionClient manualCompletionClient = manualCompletionClientFactory.getClient(taskToken); manualCompletionClient.fail(failure); } } Implementing AWS Lambda Tasks Topics • About AWS Lambda • Benefits and limitations of using Lambda tasks • Using Lambda tasks in your AWS Flow Framework for Java workflows • View the HelloLambda sample About AWS Lambda AWS Lambda is a fully managed compute service that runs your code in response to events generated by custom code or from various AWS services such as Amazon S3, DynamoDB, Amazon Kinesis, Amazon SNS, and Amazon Cognito. For more information about Lambda, see the AWS Lambda Developer Guide. Implementing Lambda Tasks API Version 2021-04-28 91 AWS Flow Framework for Java Developer Guide Amazon Simple Workflow Service provides a Lambda task so that you can run Lambda functions in place of, or alongside traditional Amazon SWF activities. Important Your AWS account will be charged for Lambda executions (requests) executed by Amazon SWF on your behalf. For details about Lambda pricing, see https://aws.amazon.com/ lambda/pricing/. Benefits and limitations of using Lambda tasks There are a number of benefits of using Lambda tasks in place of a traditional Amazon SWF activity: • Lambda tasks don’t need to be registered or versioned like Amazon SWF activity types. • You can use any existing Lambda functions that you've already defined in your workflows. • Lambda functions are called directly by Amazon SWF; there is no need for you to implement a worker program to execute them as you must do with traditional activities. • Lambda provides you with metrics and logs for tracking and analyzing your function executions. There are also a number of limitations regarding Lambda tasks that you should be aware of: • Lambda tasks can only be run in AWS regions that provide support for Lambda. See Lambda Regions and Endpoints in the Amazon Web Services General Reference for details about the currently-supported regions for Lambda. • Lambda tasks are currently supported only by the base SWF HTTP API and in the AWS Flow Framework for Java. There is currently no support for Lambda tasks in the AWS Flow Framework for Ruby. Using Lambda tasks in your AWS Flow Framework for Java workflows There are three requirements to use Lambda tasks in your AWS Flow Framework for Java workflows: • A Lambda function to execute. You can use any Lambda function that you've defined. For more information about how to create Lambda functions, see the AWS Lambda Developer Guide. Benefits and limitations of using Lambda tasks API Version 2021-04-28 92 AWS Flow Framework for Java Developer Guide • An IAM role that provides access to execute Lambda functions from your Amazon SWF workflows. • Code to schedule the Lambda task from within your workflow. Set up an IAM role Before you can invoke Lambda functions from Amazon SWF you must provide an IAM role that provides access to Lambda from Amazon SWF. You can either: • choose a pre-defined role, AWSLambdaRole, to give your workflows permission to invoke any Lambda function associated
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functions, see the AWS Lambda Developer Guide. Benefits and limitations of using Lambda tasks API Version 2021-04-28 92 AWS Flow Framework for Java Developer Guide • An IAM role that provides access to execute Lambda functions from your Amazon SWF workflows. • Code to schedule the Lambda task from within your workflow. Set up an IAM role Before you can invoke Lambda functions from Amazon SWF you must provide an IAM role that provides access to Lambda from Amazon SWF. You can either: • choose a pre-defined role, AWSLambdaRole, to give your workflows permission to invoke any Lambda function associated with your account. • define your own policy and associated role to give workflows permission to invoke particular Lambda functions, specified by their Amazon Resource Names (ARNs). Limit permissions on an IAM role You can limit permissions on an IAM role you provide to Amazon SWF by using the SourceArn and SourceAccount context keys in your resource trust policy. These keys limit the usage of an IAM policy so that it is used only from Amazon Simple Workflow Service executions that belong in the specified domain ARN. If you use both global condition context keys, the aws:SourceAccount value and the account referenced in the aws:SourceArn value must use the same account ID when used in the same policy statement. In the following trust policy example, we use the SourceArn context key to restrict the IAM service role to only be used in Amazon Simple Workflow Service executions that belong to someDomain in the account, 123456789012. { "Version": "2012-10-17", "Statement": [ { "Sid": "", "Effect": "Allow", "Principal": { "Service": "swf.amazonaws.com" }, "Action": "sts:AssumeRole", "Condition": { "ArnLike": { Using Lambda tasks in your AWS Flow Framework for Java workflows API Version 2021-04-28 93 AWS Flow Framework for Java Developer Guide "aws:SourceArn": "arn:aws:swf:*:123456789012:/domain/someDomain" } } } ] } In the following trust policy example, we use the SourceAccount context key to restrict the IAM service role to only be used in Amazon Simple Workflow Service executions in the account, 123456789012. { "Version": "2012-10-17", "Statement": [ { "Sid": "", "Effect": "Allow", "Principal": { "Service": "swf.amazonaws.com" }, "Action": "sts:AssumeRole", "Condition": { "StringLike": { "aws:SourceAccount": "123456789012" } } } ] } Providing Amazon SWF with access to invoke any Lambda role You can use the pre-defined role, AWSLambdaRole, to give your Amazon SWF workflows the ability to invoke any Lambda function associated with your account. To use AWSLambdaRole to give Amazon SWF access to invoke Lambda functions 1. Open the Amazon IAM console. 2. Choose Roles, then Create New Role. 3. Give your role a name, such as swf-lambda and choose Next Step. 4. Under AWS Service Roles, choose Amazon SWF, and choose Next Step. Using Lambda tasks in your AWS Flow Framework for Java workflows API Version 2021-04-28 94 AWS Flow Framework for Java Developer Guide 5. On the Attach Policy screen, choose AWSLambdaRole from the list. 6. Choose Next Step and then Create Role once you've reviewed the role. Defining an IAM role to provide access to invoke a specific Lambda function If you want to provide access to invoke a specific Lambda function from your workflow, you will need to define your own IAM policy. To create an IAM policy to provide access to a particular Lambda function 1. Open the Amazon IAM console. 2. Choose Policies, then Create Policy. 3. Choose Copy an AWS Managed Policy and select AWSLambdaRole from the list. A policy will be generated for you. Optionally edit its name and description to suit your needs. 4. In the Resource field of the Policy Document, add the ARN of your Lambda function(s). For example: { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": [ "lambda:InvokeFunction" ], "Resource": [ "arn:aws:lambda:us-east-1:111111000000:function:hello_lambda_function" ] } ] } Note For a complete description of how to specify resources in an IAM role, see Overview of IAM Policies in Using IAM. 5. Choose Create Policy to finish creating your policy. Using Lambda tasks in your AWS Flow Framework for Java workflows API Version 2021-04-28 95 AWS Flow Framework for Java Developer Guide You can then select this policy when creating a new IAM role, and use that role to give invoke access to your Amazon SWF workflows. This procedure is very similar to creating a role with the AWSLambdaRole policy. instead, choose your own policy when creating the role. To create a Amazon SWF role using your Lambda policy 1. Open the Amazon IAM console. 2. Choose Roles, then Create New Role. 3. Give your role a name, such as swf-lambda-function and choose Next Step. 4. Under AWS Service Roles, choose Amazon SWF, and choose Next Step. 5. On the Attach Policy screen, choose your Lambda function-specific policy from the list. 6. Choose Next Step and then Create Role once you've reviewed the role. Schedule
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SWF workflows. This procedure is very similar to creating a role with the AWSLambdaRole policy. instead, choose your own policy when creating the role. To create a Amazon SWF role using your Lambda policy 1. Open the Amazon IAM console. 2. Choose Roles, then Create New Role. 3. Give your role a name, such as swf-lambda-function and choose Next Step. 4. Under AWS Service Roles, choose Amazon SWF, and choose Next Step. 5. On the Attach Policy screen, choose your Lambda function-specific policy from the list. 6. Choose Next Step and then Create Role once you've reviewed the role. Schedule a Lambda task for execution Once you've defined an IAM role that allows you to invoke Lambda functions, you can schedule them for execution as part of your workflow. Note This process is fully demonstrated by the HelloLambda sample in the AWS SDK for Java. To schedule a Lambda task for execution 1. In your workflow implementation, get an instance of LambdaFunctionClient by calling getLambdaFunctionClient() on a DecisionContext instance. // Get a LambdaFunctionClient instance DecisionContextProvider decisionProvider = new DecisionContextProviderImpl(); DecisionContext decisionContext = decisionProvider.getDecisionContext(); LambdaFunctionClient lambdaClient = decisionContext.getLambdaFunctionClient(); 2. Schedule the task using the scheduleLambdaFunction() method on the LambdaFunctionClient, passing it the name of the Lambda function that you created and any input data for the Lambda task. Using Lambda tasks in your AWS Flow Framework for Java workflows API Version 2021-04-28 96 AWS Flow Framework for Java Developer Guide // Schedule the Lambda function for execution, using your IAM role for access. String lambda_function_name = "The name of your Lambda function."; String lambda_function_input = "Input data for your Lambda task."; lambdaClient.scheduleLambdaFunction(lambda_function_name, lambda_function_input); 3. In your workflow execution starter, add the IAM lambda role to your default workflow options by using StartWorkflowOptions.withLambdaRole(), and then pass the options when starting the workflow. // Workflow client classes are generated for you when you use the @Workflow // annotation on your workflow interface declaration. MyWorkflowClientExternalFactory clientFactory = new MyWorkflowClientExternalFactoryImpl(sdk_swf_client, swf_domain); MyWorkflowClientExternal workflow_client = clientFactory.getClient(); // Give the ARN of an IAM role that allows SWF to invoke Lambda functions on // your behalf. String lambda_iam_role = "arn:aws:iam::111111000000:role/swf_lambda_role"; StartWorkflowOptions workflow_options = new StartWorkflowOptions().withLambdaRole(lambda_iam_role); // Start the workflow execution workflow_client.helloWorld("User", workflow_options); View the HelloLambda sample A sample that provides an implementation of a workflow that uses a Lambda task is provided in the AWS SDK for Java. To view and/or run it, download the source. A full description of how to build and run the HelloLambda sample is provided in the README file provided with the AWS Flow Framework for Java samples. View the HelloLambda sample API Version 2021-04-28 97 AWS Flow Framework for Java Developer Guide Running Programs Written with the AWS Flow Framework for Java Topics • WorkflowWorker • ActivityWorker • Worker Threading Model • Worker Extensibility The framework provides worker classes to initialize the AWS Flow Framework for Java runtime and communicate with Amazon SWF. In order to implement a workflow or an activity worker, you must create and start an instance of a worker class. These worker classes are responsible for managing ongoing asynchronous operations, invoking asynchronous methods that become unblocked, and communicating with Amazon SWF. They can be configured with workflow and activity implementations, the number of threads, the task list to poll, and so on. The framework comes with two worker classes, one for activities and one for workflows. In order to run the workflow logic, you use the WorkflowWorker class. Similarly for activities the ActivityWorker class is used. These classes automatically poll Amazon SWF for activity tasks and invoke the appropriate methods in your implementation. The following example shows how to instantiate a WorkflowWorker and start polling for tasks: AmazonSimpleWorkflow swfClient = new AmazonSimpleWorkflowClient(awsCredentials); WorkflowWorker worker = new WorkflowWorker(swfClient, "domain1", "tasklist1"); // Add workflow implementation types worker.addWorkflowImplementationType(MyWorkflowImpl.class); // Start worker worker.start(); The basic steps to create an instance of the ActivityWorker and starting polling for tasks are as follows: AmazonSimpleWorkflow swfClient = new AmazonSimpleWorkflowClient(awsCredentials); Running Programs Written with the AWS Flow Framework for Java API Version 2021-04-28 98 AWS Flow Framework for Java Developer Guide ActivityWorker worker = new ActivityWorker(swfClient, "domain1", "tasklist1"); worker.addActivitiesImplementation(new MyActivitiesImpl()); // Start worker worker.start(); When you want to shut down an activity or decider, your application should shut down the instances of the worker classes being used as well as the Amazon SWF Java client instance. This will ensure that all resources used by the worker classes are properly released. worker.shutdown(); worker.awaitTermination(1, TimeUnit.MINUTES); In order to start an execution, simply create an instance of the generated external client and call the @Execute method. MyWorkflowClientExternalFactory factory = new MyWorkflowClientExternalFactoryImpl(); MyWorkflowClientExternal client = factory.getClient(); client.start(); WorkflowWorker As the name suggests, this worker class is intended for use by the workflow implementation. It is configured with a task list and the workflow implementation type. The worker class runs
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application should shut down the instances of the worker classes being used as well as the Amazon SWF Java client instance. This will ensure that all resources used by the worker classes are properly released. worker.shutdown(); worker.awaitTermination(1, TimeUnit.MINUTES); In order to start an execution, simply create an instance of the generated external client and call the @Execute method. MyWorkflowClientExternalFactory factory = new MyWorkflowClientExternalFactoryImpl(); MyWorkflowClientExternal client = factory.getClient(); client.start(); WorkflowWorker As the name suggests, this worker class is intended for use by the workflow implementation. It is configured with a task list and the workflow implementation type. The worker class runs a loop to poll for decision tasks in the specified task list. When a decision task is received, it creates an instance of the workflow implementation and calls the @Execute method to process the task. ActivityWorker For implementing activity workers, you can use the ActivityWorker class to conveniently poll a task list for activity tasks. You configure the activity worker with activity implementation objects. This worker class runs a loop to poll for activity tasks in the specified task list. When an activity task is received, it looks up the appropriate implementation that you provided and calls the activity method to process the task. Unlike the WorkflowWorker, which calls the factory to create a new instance for every decision task, the ActivityWorker simply uses the object you provided. WorkflowWorker API Version 2021-04-28 99 AWS Flow Framework for Java Developer Guide The ActivityWorker class uses the AWS Flow Framework for Java annotations to determine the registration and execution options. Worker Threading Model In the AWS Flow Framework for Java, the embodiment of an activity or decider is an instance of the worker class. Your application is responsible for configuring and instantiating the worker object on each machine and process that should act as a worker. The worker object then automatically receives tasks from Amazon SWF, dispatches them to your activity or workflow implementation and reports results to Amazon SWF. It is possible for a single workflow instance to span many workers. When Amazon SWF has one or more pending activity tasks, it assigns a task to the first available worker, then the next one, and so on. This makes it possible for tasks belonging to the same workflow instance to be processed on different workers concurrently. Moreover, each worker can be configured to process tasks on multiple threads. This means that the activity tasks of a workflow instance can run concurrently even if there is only one worker. Decision tasks behave similarly with the exception that Amazon SWF guarantees that for a given workflow execution only one decision can be executed at a time. A single workflow execution will typically require multiple decision tasks; hence, it may end up executing on multiple processes and threads as well. The decider is configured with the type of the workflow implementation. Worker Threading Model API Version 2021-04-28 100 AWS Flow Framework for Java Developer Guide When a decision task is received by the decider, it creates an instance (object) of the workflow implementation. The framework provides an extensible factory pattern for creating these instances. The default workflow factory creates a new object every time. You can provide custom factories to override this behavior. Contrary to deciders, which are configured with workflow implementation types, activity workers are configured with instances (objects) of the activity implementations. When an activity task is received by the activity worker, it is dispatched to the appropriate activity implementation object. The workflow worker maintains a single pool of threads and executes the workflow on the same thread that was used to poll Amazon SWF for the task. Because activities are long running (at least when compared to the workflow logic), the activity worker class maintains two separate pools of threads; one for polling Amazon SWF for activity tasks and the other for processing tasks by executing the activity implementation. This allows you to configure the number of threads to poll for tasks separate from the number of threads to execute them. For example, you can have a small number of threads to poll and a large number of threads to execute the tasks. The activity worker class polls Amazon SWF for a task only when it has a free poll thread as well as a free thread to process the task. This threading and instancing behavior implies that: 1. Activity implementations must be stateless. You should not use instance variables to store application state in activity objects. You may, however, use fields to store resources such as database connections. 2. Activity implementations must be thread safe. Because the same instance may be used to process tasks from different threads at the same time, access to shared resources from the activity code must be synchronized. Worker Threading Model API Version 2021-04-28 101
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a task only when it has a free poll thread as well as a free thread to process the task. This threading and instancing behavior implies that: 1. Activity implementations must be stateless. You should not use instance variables to store application state in activity objects. You may, however, use fields to store resources such as database connections. 2. Activity implementations must be thread safe. Because the same instance may be used to process tasks from different threads at the same time, access to shared resources from the activity code must be synchronized. Worker Threading Model API Version 2021-04-28 101 AWS Flow Framework for Java Developer Guide 3. Workflow implementation can be stateful, and instance variables may be used to store state. Even though a new instance of the workflow implementation is created to process each decision task, the framework will ensure that state is properly recreated. However, the workflow implementation must be deterministic. See the section Understanding a Task in AWS Flow Framework for Java for more details. 4. Workflow implementations don't need to be thread safe when using the default factory. The default implementation ensures that only one thread uses an instance of the workflow implementation at a time. Worker Extensibility The AWS Flow Framework for Java also contains a couple of low-level worker classes that give you fine-grained control as well as extensibility. Using them, you can completely customize workflow and activity type registration and set factories for creating implementation objects. These workers are GenericWorkflowWorker and GenericActivityWorker. The GenericWorkflowWorker can be configured with a factory for creating workflow definition factories. The workflow definition factory is responsible for creating instances of the workflow implementation and for providing configuration settings such as registration options. Under normal circumstances, you should use the WorkflowWorker class directly. It will automatically create and configure implementation of the factories provided in the framework, POJOWorkflowDefinitionFactoryFactory and POJOWorkflowDefinitionFactory. The factory requires that the workflow implementation class must have a no argument constructor. This constructor is used to create instances of the workflow object at run time. The factory looks at the annotations you used on the workflow interface and implementation to create appropriate registration and execution options. You may provide your own implementation of the factories by implementing WorkflowDefinitionFactory, WorkflowDefinitionFactoryFactory, and WorkflowDefinition. The WorkflowDefinition class is used by the worker class to dispatch decision tasks and signals. By implementing these base classes, you can completely customize the factory and the dispatch of requests to the workflow implementation. For example, you can use these extensibility points to provide a custom programming model for writing workflows, for instance, based on your own annotations or generating it from WSDL instead of the code first approach used by the framework. In order to use your custom factories, you will have to use the GenericWorkflowWorker class. For more details about these classes, see the AWS SDK for Java documentation. Worker Extensibility API Version 2021-04-28 102 AWS Flow Framework for Java Developer Guide Similarly, GenericActivityWorker allows you to provide a custom activity implementation factory. By implementing the ActivityImplementationFactory and ActivityImplementation classes you can completely control activity instantiation as well as customize registration and execution options. For more details of these classes, see the AWS SDK for Java documentation. Execution Context Topics • Decision Context • Activity Execution Context The framework provides an ambient context to workflow and activity implementations. This context is specific to the task being processed and provides some utilities that you can use in your implementation. A context object is created every time a new task is processed by the worker. Decision Context When a decision task is executed, the framework provides the context to workflow implementation through the DecisionContext class. DecisionContext provides context-sensitive information like workflow execution run Id and clock and timer functionality. Accessing DecisionContext in Workflow Implementation You can access the DecisionContext in your workflow implementation using the DecisionContextProviderImpl class. Alternatively, you can inject the context in a field or property of your workflow implementation using Spring as shown in the Testability and Dependency Injection section. DecisionContextProvider contextProvider = new DecisionContextProviderImpl(); DecisionContext context = contextProvider.getDecisionContext(); Creating a Clock and Timer The DecisionContext contains a property of type WorkflowClock that provides timer and clock functionality. Because the workflow logic needs to be deterministic, you should not directly Execution Context API Version 2021-04-28 103 AWS Flow Framework for Java Developer Guide use the system clock in your workflow implementation. The currentTimeMills method on the WorkflowClock returns the time of the start event of the decision being processed. This ensures that you get the same time value during replay, hence, making your workflow logic deterministic. WorkflowClock also has a createTimer method which returns a Promise object that becomes ready after the specified interval. You can use this value as a parameter to other asynchronous methods to delay their execution
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workflow logic needs to be deterministic, you should not directly Execution Context API Version 2021-04-28 103 AWS Flow Framework for Java Developer Guide use the system clock in your workflow implementation. The currentTimeMills method on the WorkflowClock returns the time of the start event of the decision being processed. This ensures that you get the same time value during replay, hence, making your workflow logic deterministic. WorkflowClock also has a createTimer method which returns a Promise object that becomes ready after the specified interval. You can use this value as a parameter to other asynchronous methods to delay their execution by the specified period of time. This way you can effectively schedule an asynchronous method or activity for execution at a later time. The example in the following listing demonstrates how to periodically call an activity. @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 60, defaultTaskStartToCloseTimeoutSeconds = 10) public interface PeriodicWorkflow { @Execute(version = "1.0") void periodicWorkflow(); } @Activities(version = "1.0") @ActivityRegistrationOptions(defaultTaskScheduleToStartTimeoutSeconds = 300, defaultTaskStartToCloseTimeoutSeconds = 3600) public interface PeriodicActivity { void activity1(); } public class PeriodicWorkflowImpl implements PeriodicWorkflow { private DecisionContextProvider contextProvider = new DecisionContextProviderImpl(); private WorkflowClock clock = contextProvider.getDecisionContext().getWorkflowClock(); @Override public void periodicWorkflow() { callPeriodicActivity(0); } @Asynchronous private void callPeriodicActivity(int count, Promise<?>... waitFor) { Decision Context API Version 2021-04-28 104 AWS Flow Framework for Java Developer Guide if (count == 100) { return; } PeriodicActivityClient client = new PeriodicActivityClientImpl(); // call activity Promise<Void> activityCompletion = client.activity1(); Promise<Void> timer = clock.createTimer(3600); // Repeat the activity either after 1 hour or after previous activity run // if it takes longer than 1 hour callPeriodicActivity(count + 1, timer, activityCompletion); } } public class PeriodicActivityImpl implements PeriodicActivity { @Override public void activity1() { ... } } In the above listing, the callPeriodicActivity asynchronous method calls activity1 and then creates a timer using the current AsyncDecisionContext. It passes the returned Promise as an argument to a recursive call to itself. This recursive call waits until the timer fires (1 hour in this example) before executing. Activity Execution Context Just as the DecisionContext provides context information when a decision task is being processed, ActivityExecutionContext provides similar context information when an activity task is being processed. This context is available to your activity code through ActivityExecutionContextProviderImpl class. ActivityExecutionContextProvider provider = new ActivityExecutionContextProviderImpl(); ActivityExecutionContext aec = provider.getActivityExecutionContext(); Using ActivityExecutionContext, you can perform the following: Activity Execution Context API Version 2021-04-28 105 AWS Flow Framework for Java Developer Guide Heartbeat a Long Running Activity If the activity is long running, it must periodically report its progress to Amazon SWF to let it know that the task is still making progress. In the absence of such a heartbeat, the task may timeout if a task heartbeat timeout was set at activity type registration or while scheduling the activity. In order to send a heartbeat, you can use the recordActivityHeartbeat method on ActivityExecutionContext. Heartbeat also provides a mechanism for canceling ongoing activities. See the Error Handling section for more details and an example. Get Details of the Activity Task If you want, you can get all the details of the activity task that were passed by Amazon SWF when the executor got the task. This includes information regarding the inputs to the task, task type, task token, etc. If you want to implement an activity that is manually completed—for example, by a human action—then you must use the ActivityExecutionContext to retrieve the task token and pass it to the process that will eventually complete the activity task. See the section on Manually Completing Activities for more details. Get the Amazon SWF Client Object that is Being Used by the Executor The Amazon SWF client object being used by the executor can be retrieved by calling getService method on ActivityExecutionContext. This is useful if you want to make a direct call to the Amazon SWF service. Child Workflow Executions In the examples so far, we have started workflow execution directly from an application. However, a workflow execution may be started from within a workflow by calling the workflow entry point method on the generated client. When a workflow execution is started from the context of another workflow execution, it is called a child workflow execution. This allows you to refactor complex workflows into smaller units and potentially share them across different workflows. For example, you can create a payment processing workflow and call it from an order processing workflow. Semantically, the child workflow execution behaves the same as a standalone workflow except for the following differences: 1. When the parent workflow terminates due to an explicit action by the user—for example, by calling the TerminateWorkflowExecution Amazon SWF API, or it is terminated due to a Child Workflow Executions API Version 2021-04-28 106 AWS Flow Framework for Java Developer Guide timeout—then the fate of the child workflow execution will be determined by a child policy. You
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and potentially share them across different workflows. For example, you can create a payment processing workflow and call it from an order processing workflow. Semantically, the child workflow execution behaves the same as a standalone workflow except for the following differences: 1. When the parent workflow terminates due to an explicit action by the user—for example, by calling the TerminateWorkflowExecution Amazon SWF API, or it is terminated due to a Child Workflow Executions API Version 2021-04-28 106 AWS Flow Framework for Java Developer Guide timeout—then the fate of the child workflow execution will be determined by a child policy. You can set this child policy to terminate, cancel, or abandon (keep running) child workflow executions. 2. The output of the child workflow (return value of the entry point method) can be used by the parent workflow execution just like the Promise<T> returned by an asynchronous method. This is different from standalone executions where the application must get the output by using Amazon SWF APIs. In the following example, the OrderProcessor workflow creates a PaymentProcessor child workflow: @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 60, defaultTaskStartToCloseTimeoutSeconds = 10) public interface OrderProcessor { @Execute(version = "1.0") void processOrder(Order order); } public class OrderProcessorImpl implements OrderProcessor { PaymentProcessorClientFactory factory = new PaymentProcessorClientFactoryImpl(); @Override public void processOrder(Order order) { float amount = order.getAmount(); CardInfo cardInfo = order.getCardInfo(); PaymentProcessorClient childWorkflowClient = factory.getClient(); childWorkflowClient.processPayment(amount, cardInfo); } } @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 60, defaultTaskStartToCloseTimeoutSeconds = 10) public interface PaymentProcessor { @Execute(version = "1.0") Child Workflow Executions API Version 2021-04-28 107 AWS Flow Framework for Java Developer Guide void processPayment(float amount, CardInfo cardInfo); } public class PaymentProcessorImpl implements PaymentProcessor { PaymentActivitiesClient activitiesClient = new PaymentActivitiesClientImpl(); @Override public void processPayment(float amount, CardInfo cardInfo) { Promise<PaymentType> payType = activitiesClient.getPaymentType(cardInfo); switch(payType.get()) { case Visa: activitiesClient.processVisa(amount, cardInfo); break; case Amex: activitiesClient.processAmex(amount, cardInfo); break; default: throw new UnSupportedPaymentTypeException(); } } } @Activities(version = "1.0") @ActivityRegistrationOptions(defaultTaskScheduleToStartTimeoutSeconds = 3600, defaultTaskStartToCloseTimeoutSeconds = 3600) public interface PaymentActivities { PaymentType getPaymentType(CardInfo cardInfo); void processVisa(float amount, CardInfo cardInfo); void processAmex(float amount, CardInfo cardInfo); } Continuous Workflows In some use cases, you may need a workflow that executes forever or runs for a long duration, for example, a workflow that monitors the health of a server fleet. Continuous Workflows API Version 2021-04-28 108 AWS Flow Framework for Java Developer Guide Note Because Amazon SWF keeps the entire history of a workflow execution, the history will keep growing over time. The framework retrieves this history from Amazon SWF when it performs a replay, and this will become expensive if the history size is too large. In such long running or continuous workflows, you should periodically close the current execution and start a new one to continue processing. This is a logical continuation of the workflow execution. The generated self client can be used for this purpose. In your workflow implementation, simply call the @Execute method on the self client. Once the current execution completes, the framework will start a new execution using the same workflow Id. You can also continue the execution by calling the continueAsNewOnCompletion method on the GenericWorkflowClient that you can retrieve from the current DecisionContext. For example, the following workflow implementation sets a timer to fire after a day and calls its own entry point to start a new execution. public class ContinueAsNewWorkflowImpl implements ContinueAsNewWorkflow { private DecisionContextProvider contextProvider = new DecisionContextProviderImpl(); private ContinueAsNewWorkflowSelfClient selfClient = new ContinueAsNewWorkflowSelfClientImpl(); private WorkflowClock clock = contextProvider.getDecisionContext().getWorkflowClock(); @Override public void startWorkflow() { Promise<Void> timer = clock.createTimer(86400); continueAsNew(timer); } @Asynchronous void continueAsNew(Promise<Void> timer) { selfClient.startWorkflow(); } Continuous Workflows API Version 2021-04-28 109 AWS Flow Framework for Java } Developer Guide When a workflow recursively calls itself, the framework will close the current workflow when all pending tasks have completed and start a new workflow execution. Note that as long as there are pending tasks, the current workflow execution will not close. The new execution will not automatically inherit any history or data from the original execution; if you want to carry over some state to the new execution, then you must pass it explicitly as input. Setting task priority in Amazon SWF By default, tasks on a task list are delivered based upon their arrival time: tasks that are scheduled first are generally run first, as far as possible. By setting an optional task priority, you can give priority to certain tasks: Amazon SWF will attempt to deliver higher-priority tasks on a task list before those with lower priority. You can set task priorities for both workflows and activities. A workflow's task priority doesn't affect the priority of any activity tasks it schedules, nor does it affect any child workflows it starts. The default priority for an activity or workflow is set (either by you or by Amazon SWF) during registration, and the registered task priority is always used unless it is overridden while scheduling the activity or
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possible. By setting an optional task priority, you can give priority to certain tasks: Amazon SWF will attempt to deliver higher-priority tasks on a task list before those with lower priority. You can set task priorities for both workflows and activities. A workflow's task priority doesn't affect the priority of any activity tasks it schedules, nor does it affect any child workflows it starts. The default priority for an activity or workflow is set (either by you or by Amazon SWF) during registration, and the registered task priority is always used unless it is overridden while scheduling the activity or starting a workflow execution. Task priority values can range from "-2147483648" to "2147483647", with higher numbers indicating higher priority. If you don't set the task priority for an activity or workflow, it will be assigned a priority of zero ("0"). Topics • Setting Task Priority for Workflows • Setting Task Priority for Activities Setting Task Priority for Workflows You can set the task priority for a workflow when you register it or start it. The task priority that is set when the workflow type is registered is used as the default for any workflow executions of that type, unless it is overridden when starting the workflow execution. To register a workflow type with a default task priority, set the defaultTaskPriority option in WorkflowRegistrationOptions when declaring it: Setting task priority API Version 2021-04-28 110 AWS Flow Framework for Java Developer Guide @Workflow @WorkflowRegistrationOptions( defaultTaskPriority = 10, defaultTaskStartToCloseTimeoutSeconds = 240) public interface PriorityWorkflow { @Execute(version = "1.0") void startWorkflow(int a); } You can also set the taskPriority for a workflow when you start it, overriding the registered (default) task priority. StartWorkflowOptions priorityWorkflowOptions = new StartWorkflowOptions().withTaskPriority(10); PriorityWorkflowClientExternalFactory cf = new PriorityWorkflowClientExternalFactoryImpl(swfService, domain); priority_workflow_client = cf.getClient(); priority_workflow_client.startWorkflow( "Smith, John", priorityWorkflowOptions); Additionally, you can set the task priority when starting a child workflow or continuing a workflow as new. For example, you can set the taskPriority option in ContinueAsNewWorkflowExecutionParameters or in StartChildWorkflowExecutionParameters. Setting Task Priority for Activities You can set the task priority for an activity either when registering it or when scheduling it. The task priority that is set when registering an activity type is used as the default priority when the activity is run, unless it is overridden when scheduling the activity. To register an activity type with a default task priority, set the defaultTaskPriority option in ActivityRegistrationOptions when declaring it: @Activities(version = "1.0") @ActivityRegistrationOptions( defaultTaskPriority = 10, Setting Task Priority for Activities API Version 2021-04-28 111 AWS Flow Framework for Java Developer Guide defaultTaskStartToCloseTimeoutSeconds = 120) public interface ImportantActivities { int doSomethingImportant(); } You can also set the taskPriority for an activity when you schedule it, overriding the registered (default) task priority. ActivitySchedulingOptions activityOptions = new ActivitySchedulingOptions.withTaskPriority(10); ImportantActivitiesClient activityClient = new ImportantActivitiesClientImpl(); activityClient.doSomethingImportant(activityOptions); DataConverters When your workflow implementation calls a remote activity, the inputs passed to it and the result of executing the activity must be serialized so they can be sent over the wire. The framework uses the DataConverter class for this purpose. This is an abstract class that you can implement to provide your own serializer. A default Jackson serializer–based implementation, JsonDataConverter, is provided in the framework. For more details, see the AWS SDK for Java documentation. Refer to the Jackson JSON Processor documentation for details about how Jackson performs serialization as well as Jackson annotations that can be used to influence it. The wire format used is considered part of the contract. Hence, you can specify a DataConverter on your activities and workflow interfaces by setting the DataConverter property of the @Activities and @Workflow annotations. The framework will create objects of the DataConverter type you specified on @Activities annotation to serialize the inputs to the activity and to deserialize its result. Similarly, objects of the DataConverter type you specify on @Workflow annotation will be used to serialize parameters you pass to the workflow, and in the case of child workflow, to deserialize the result. In addition to inputs, the framework also passes additional data to Amazon SWF—for example, exception details—the workflow serializer will be used for serializing this data as well. You can also provide an instance of the DataConverter if you don't want the framework to automatically create it. The generated clients have constructor overloads that take a DataConverter. DataConverters API Version 2021-04-28 112 AWS Flow Framework for Java Developer Guide If you don't specify a DataConverter type and don't pass a DataConverter object, the JsonDataConverter will be used by default. Passing Data to Asynchronous Methods Topics • Passing Collections and Maps to Asynchronous Methods • Settable<T> • @NoWait • Promise<Void> • AndPromise and OrPromise The use of Promise<T> has been explained in previous sections. Some advanced use cases of Promise<T> are discussed here. Passing Collections and Maps to Asynchronous Methods The framework supports passing arrays, collections, and
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it. The generated clients have constructor overloads that take a DataConverter. DataConverters API Version 2021-04-28 112 AWS Flow Framework for Java Developer Guide If you don't specify a DataConverter type and don't pass a DataConverter object, the JsonDataConverter will be used by default. Passing Data to Asynchronous Methods Topics • Passing Collections and Maps to Asynchronous Methods • Settable<T> • @NoWait • Promise<Void> • AndPromise and OrPromise The use of Promise<T> has been explained in previous sections. Some advanced use cases of Promise<T> are discussed here. Passing Collections and Maps to Asynchronous Methods The framework supports passing arrays, collections, and maps as Promise types to asynchronous methods. For example, an asynchronous method may take Promise<ArrayList<String>> as an argument as shown in the following listing. @Asynchronous public void printList(Promise<List<String>> list) { for (String s: list.get()) { activityClient.printActivity(s); } } Semantically, this behaves as any other Promise typed parameter and the asynchronous method will wait until the collection becomes available before executing. If the members of a collection are Promise objects, then you can make the framework wait for all members to become ready as shown in the following snippet. This will make the asynchronous method wait on each member of the collection to become available. @Asynchronous public void printList(@Wait List<Promise<String>> list) { for (Promise<String> s: list) { activityClient.printActivity(s); Passing Data to Asynchronous Methods API Version 2021-04-28 113 AWS Flow Framework for Java Developer Guide } } Note that the @Wait annotation must be used on the parameter to indicate that it contains Promise objects. Note also that the activity printActivity takes a String argument but the matching method in the generated client takes a Promise<String>. We are calling the method on the client and not invoking the activity method directly. Settable<T> Settable<T> is a derived type of Promise<T> that provides a set method that allows you to manually set the value of a Promise. For example, the following workflow waits for a signal to be received by waiting on a Settable<?>, which is set in the signal method: public class MyWorkflowImpl implements MyWorkflow{ final Settable<String> result = new Settable<String>(); //@Execute method @Override public Promise<String> start() { return done(result); } //Signal @Override public void manualProcessCompletedSignal(String data) { result.set(data); } @Asynchronous public Promise<String> done(Settable<String> result){ return result; } } A Settable<?> can also be chained to another promise at a time. You can use AndPromise and OrPromise to group promises. You can unchain a chained Settable by calling the unchain() method on it. When chained, the Settable<?> automatically becomes ready when the promise that it is chained to becomes ready. Chaining is especially useful when you want to use a Settable<T> API Version 2021-04-28 114 AWS Flow Framework for Java Developer Guide promise returned from within the scope of a doTry() in other parts of your program. Because TryCatchFinally is used as a nested class, you can't declare a Promise<> in the parent's scope and set it in doTry(). This is because Java requires variables to be declared in parent scope and used in nested classes to be marked final. For example: @Asynchronous public Promise<String> chain(final Promise<String> input) { final Settable<String> result = new Settable<String>(); new TryFinally() { @Override protected void doTry() throws Throwable { Promise<String> resultToChain = activity1(input); activity2(resultToChain); // Chain the promise to Settable result.chain(resultToChain); } @Override protected void doFinally() throws Throwable { if (result.isReady()) { // Was a result returned before the exception? // Do cleanup here } } }; return result; } A Settable can be chained to one promise at a time. You can unchain a chained Settable by calling the unchain() method on it. @NoWait When you pass a Promise to an asynchronous method, by default, the framework will wait for the Promise(s) to become ready before executing the method (except for collection types). You may override this behavior by using the @NoWait annotation on parameters in the declaration of the asynchronous method. This is useful if you are passing in Settable<T>, which will be set by the asynchronous method itself. @NoWait API Version 2021-04-28 115 AWS Flow Framework for Java Promise<Void> Developer Guide Dependencies in asynchronous methods are implemented by passing the Promise returned by one method as an argument to another. However, there may be cases where you want to return void from a method, but still want other asynchronous methods to execute after its completion. In such cases, you can use Promise<Void> as the return type of the method. The Promise class provides a static Void method that you can use to create a Promise<Void> object. This Promise will become ready when the asynchronous method finishes execution. You can pass this Promise to another asynchronous method just like any other Promise object. If you are using Settable<Void>, then call the set method on it with null to make it ready. AndPromise and OrPromise AndPromise
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cases where you want to return void from a method, but still want other asynchronous methods to execute after its completion. In such cases, you can use Promise<Void> as the return type of the method. The Promise class provides a static Void method that you can use to create a Promise<Void> object. This Promise will become ready when the asynchronous method finishes execution. You can pass this Promise to another asynchronous method just like any other Promise object. If you are using Settable<Void>, then call the set method on it with null to make it ready. AndPromise and OrPromise AndPromise and OrPromise allow you to group multiple Promise<> objects into a single logical promise. An AndPromise becomes ready when all promises used to construct it become ready. An OrPromise becomes ready when any promise in the collection of promises used to construct it becomes ready. You can call getValues() on AndPromise and OrPromise to retrieve the list of values of the constituent promises. Testability and Dependency Injection Topics • Spring Integration • JUnit Integration The framework is designed to be Inversion of Control (IoC) friendly. Activity and workflow implementations as well as the framework supplied workers and context objects can be configured and instantiated using containers like Spring. Out of the box, the framework provides integration with the Spring Framework. In addition, integration with JUnit has been provided for unit testing workflow and activity implementations. Spring Integration The com.amazonaws.services.simpleworkflow.flow.spring package contains classes that make it easy to use the Spring framework in your applications. These include a custom Scope and Spring-aware activity and workflow workers: WorkflowScope, SpringWorkflowWorker and Promise<Void> API Version 2021-04-28 116 AWS Flow Framework for Java Developer Guide SpringActivityWorker. These classes allow you to configure your workflow and activity implementations as well as the workers entirely through Spring. WorkflowScope WorkflowScope is a custom Spring Scope implementation provided by the framework. This scope allows you to create objects in the Spring container whose lifetime is scoped to that of a decision task. The beans in this scope are instantiated every time a new decision task is received by the worker. You should use this scope for workflow implementation beans and any other beans it depends on. The Spring-provided singleton and prototype scopes should not be used for workflow implementation beans because the framework requires that a new bean be created for each decision task. Failure to do so will result in unexpected behavior. The following example shows a snippet of Spring configuration that registers the WorkflowScope and then uses it for configuring a workflow implementation bean and an activity client bean. <!-- register AWS Flow Framework for Java WorkflowScope --> <bean class="org.springframework.beans.factory.config.CustomScopeConfigurer"> <property name="scopes"> <map> <entry key="workflow"> <bean class="com.amazonaws.services.simpleworkflow.flow.spring.WorkflowScope" /> </entry> </map> </property> </bean> <!-- activities client --> <bean id="activitiesClient" class="aws.flow.sample.MyActivitiesClientImpl" scope="workflow"> </bean> <!-- workflow implementation --> <bean id="workflowImpl" class="aws.flow.sample.MyWorkflowImpl" scope="workflow"> <property name="client" ref="activitiesClient"/> <aop:scoped-proxy proxy-target-class="false" /> </bean> The line of configuration: <aop:scoped-proxy proxy-target-class="false" />, used in the configuration of the workflowImpl bean, is required because the WorkflowScope Spring Integration API Version 2021-04-28 117 AWS Flow Framework for Java Developer Guide doesn't support proxying using CGLIB. You should use this configuration for any bean in the WorkflowScope that is wired to another bean in a different scope. In this case, the workflowImpl bean needs to be wired to a workflow worker bean in singleton scope (see complete example below). You can learn more about using custom scopes in the Spring Framework documentation. Spring-Aware Workers When using Spring, you should use the Spring-aware worker classes provided by the framework: SpringWorkflowWorker and SpringActivityWorker. These workers can be injected in your application using Spring as shown in the next example. The Spring-aware workers implement Spring's SmartLifecycle interface and, by default, automatically start polling for tasks when the Spring context is initialized. You can turn off this functionality by setting the disableAutoStartup property of the worker to true. The following example shows how to configure a decider. This example uses MyActivities and MyWorkflow interfaces (not shown here) and corresponding implementations, MyActivitiesImpl and MyWorkflowImpl. The generated client interfaces and implementations are MyWorkflowClient/MyWorkflowClientImpl and MyActivitiesClient/MyActivitiesClientImpl (also not shown here). The activities client is injected in the workflow implementation using Spring's auto wire feature: public class MyWorkflowImpl implements MyWorkflow { @Autowired public MyActivitiesClient client; @Override public void start() { client.activity1(); } } The Spring configuration for the decider is as follows: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context" Spring Integration API Version 2021-04-28 118 AWS Flow Framework for Java Developer Guide xsi:schemaLocation="http://www.springframework.org/schema/beans http:// www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/ spring-aop-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- register custom workflow scope --> <bean class="org.springframework.beans.factory.config.CustomScopeConfigurer"> <property name="scopes"> <map> <entry key="workflow"> <bean class="com.amazonaws.services.simpleworkflow.flow.spring.WorkflowScope" /> </entry> </map> </property> </bean> <context:annotation-config/> <bean id="accesskeys" class="com.amazonaws.auth.BasicAWSCredentials"> <constructor-arg value="{AWS.Access.ID}"/> <constructor-arg value="{AWS.Secret.Key}"/> </bean> <bean id="clientConfiguration" class="com.amazonaws.ClientConfiguration"> <property name="socketTimeout" value="70000" /> </bean> <!-- Amazon SWF client --> <bean id="swfClient" class="com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClient"> <constructor-arg
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MyWorkflowImpl implements MyWorkflow { @Autowired public MyActivitiesClient client; @Override public void start() { client.activity1(); } } The Spring configuration for the decider is as follows: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context" Spring Integration API Version 2021-04-28 118 AWS Flow Framework for Java Developer Guide xsi:schemaLocation="http://www.springframework.org/schema/beans http:// www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/ spring-aop-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- register custom workflow scope --> <bean class="org.springframework.beans.factory.config.CustomScopeConfigurer"> <property name="scopes"> <map> <entry key="workflow"> <bean class="com.amazonaws.services.simpleworkflow.flow.spring.WorkflowScope" /> </entry> </map> </property> </bean> <context:annotation-config/> <bean id="accesskeys" class="com.amazonaws.auth.BasicAWSCredentials"> <constructor-arg value="{AWS.Access.ID}"/> <constructor-arg value="{AWS.Secret.Key}"/> </bean> <bean id="clientConfiguration" class="com.amazonaws.ClientConfiguration"> <property name="socketTimeout" value="70000" /> </bean> <!-- Amazon SWF client --> <bean id="swfClient" class="com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClient"> <constructor-arg ref="accesskeys" /> <constructor-arg ref="clientConfiguration" /> <property name="endpoint" value="{service.url}" /> </bean> <!-- activities client --> <bean id="activitiesClient" class="aws.flow.sample.MyActivitiesClientImpl" scope="workflow"> </bean> <!-- workflow implementation --> <bean id="workflowImpl" class="aws.flow.sample.MyWorkflowImpl" scope="workflow"> Spring Integration API Version 2021-04-28 119 AWS Flow Framework for Java Developer Guide <property name="client" ref="activitiesClient"/> <aop:scoped-proxy proxy-target-class="false" /> </bean> <!-- workflow worker --> <bean id="workflowWorker" class="com.amazonaws.services.simpleworkflow.flow.spring.SpringWorkflowWorker"> <constructor-arg ref="swfClient" /> <constructor-arg value="domain1" /> <constructor-arg value="tasklist1" /> <property name="registerDomain" value="true" /> <property name="domainRetentionPeriodInDays" value="1" /> <property name="workflowImplementations"> <list> <ref bean="workflowImpl" /> </list> </property> </bean> </beans> Because the SpringWorkflowWorker is fully configured in Spring and automatically starts polling when the Spring context is initialized, the host process for the decider is simple: public class WorkflowHost { public static void main(String[] args){ ApplicationContext context = new FileSystemXmlApplicationContext("resources/spring/ WorkflowHostBean.xml"); System.out.println("Workflow worker started"); } } Similarly, the activity worker can be configured as follows: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http:// www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/ spring-aop-2.5.xsd Spring Integration API Version 2021-04-28 120 AWS Flow Framework for Java Developer Guide http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- register custom scope --> <bean class="org.springframework.beans.factory.config.CustomScopeConfigurer"> <property name="scopes"> <map> <entry key="workflow"> <bean class="com.amazonaws.services.simpleworkflow.flow.spring.WorkflowScope" /> </entry> </map> </property> </bean> <bean id="accesskeys" class="com.amazonaws.auth.BasicAWSCredentials"> <constructor-arg value="{AWS.Access.ID}"/> <constructor-arg value="{AWS.Secret.Key}"/> </bean> <bean id="clientConfiguration" class="com.amazonaws.ClientConfiguration"> <property name="socketTimeout" value="70000" /> </bean> <!-- Amazon SWF client --> <bean id="swfClient" class="com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClient"> <constructor-arg ref="accesskeys" /> <constructor-arg ref="clientConfiguration" /> <property name="endpoint" value="{service.url}" /> </bean> <!-- activities impl --> <bean name="activitiesImpl" class="asadj.spring.test.MyActivitiesImpl"> </bean> <!-- activity worker --> <bean id="activityWorker" class="com.amazonaws.services.simpleworkflow.flow.spring.SpringActivityWorker"> <constructor-arg ref="swfClient" /> <constructor-arg value="domain1" /> <constructor-arg value="tasklist1" /> <property name="registerDomain" value="true" /> Spring Integration API Version 2021-04-28 121 AWS Flow Framework for Java Developer Guide <property name="domainRetentionPeriodInDays" value="1" /> <property name="activitiesImplementations"> <list> <ref bean="activitiesImpl" /> </list> </property> </bean> </beans> The activity worker host process is similar to the decider: public class ActivityHost { public static void main(String[] args) { ApplicationContext context = new FileSystemXmlApplicationContext( "resources/spring/ActivityHostBean.xml"); System.out.println("Activity worker started"); } } Injecting Decision Context If your workflow implementation depends on the context objects, then you can easily inject them through Spring as well. The framework automatically registers context-related beans in the Spring container. For example, in the following snippet, the various context objects have been auto wired. No other Spring configuration of the context objects is required. public class MyWorkflowImpl implements MyWorkflow { @Autowired public MyActivitiesClient client; @Autowired public WorkflowClock clock; @Autowired public DecisionContext dcContext; @Autowired public GenericActivityClient activityClient; @Autowired public GenericWorkflowClient workflowClient; @Autowired public WorkflowContext wfContext; @Override public void start() { client.activity1(); Spring Integration API Version 2021-04-28 122 AWS Flow Framework for Java Developer Guide } } If you want to configure the context objects in the workflow implementation through Spring XML configuration, then use the bean names declared in the WorkflowScopeBeanNames class in the com.amazonaws.services.simpleworkflow.flow.spring package. For example: <!-- workflow implementation --> <bean id="workflowImpl" class="asadj.spring.test.MyWorkflowImpl" scope="workflow"> <property name="client" ref="activitiesClient"/> <property name="clock" ref="workflowClock"/> <property name="activityClient" ref="genericActivityClient"/> <property name="dcContext" ref="decisionContext"/> <property name="workflowClient" ref="genericWorkflowClient"/> <property name="wfContext" ref="workflowContext"/> <aop:scoped-proxy proxy-target-class="false" /> </bean> Alternatively, you may inject a DecisionContextProvider in the workflow implementation bean and use it to create the context. This can be useful if you want to provide custom implementations of the provider and context. Injecting Resources in Activities You can instantiate and configure activity implementations using an Inversion of Control (IoC) container and easily inject resources like database connections by declaring them as properties of the activity implementation class. Such resources will typically be scoped as singletons. Note that activity implementations are called by the activity worker on multiple threads. Therefore, access to shared resources must be synchronized. JUnit Integration The framework provides JUnit extensions as well as test implementations of the context objects, such as a test clock, that you can use to write and run unit tests with JUnit. With these extensions, you can test your workflow implementation locally inline. Writing a Simple Unit Test In order to write tests for your workflow, use the WorkflowTest class in the com.amazonaws.services.simpleworkflow.flow.junit package. This class is a framework-specific JUnit Integration API Version 2021-04-28 123 AWS Flow Framework for Java Developer Guide JUnit MethodRule implementation and runs your workflow code locally, calling activities inline as opposed to going through Amazon SWF. This gives you the flexibility to run your tests as frequently as you desire without incurring any charges. In order to use this class, simply declare
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run unit tests with JUnit. With these extensions, you can test your workflow implementation locally inline. Writing a Simple Unit Test In order to write tests for your workflow, use the WorkflowTest class in the com.amazonaws.services.simpleworkflow.flow.junit package. This class is a framework-specific JUnit Integration API Version 2021-04-28 123 AWS Flow Framework for Java Developer Guide JUnit MethodRule implementation and runs your workflow code locally, calling activities inline as opposed to going through Amazon SWF. This gives you the flexibility to run your tests as frequently as you desire without incurring any charges. In order to use this class, simply declare a field of type WorkflowTest and annotate it with the @Rule annotation. Before running your tests, create a new WorkflowTest object and add your activity and workflow implementations to it. You can then use the generated workflow client factory to create a client and start an execution of the workflow. The framework also provides a custom JUnit runner, FlowBlockJUnit4ClassRunner, that you must use for your workflow tests. For example: @RunWith(FlowBlockJUnit4ClassRunner.class) public class BookingWorkflowTest { @Rule public WorkflowTest workflowTest = new WorkflowTest(); List<String> trace; private BookingWorkflowClientFactory workflowFactory = new BookingWorkflowClientFactoryImpl(); @Before public void setUp() throws Exception { trace = new ArrayList<String>(); // Register activity implementation to be used during test run BookingActivities activities = new BookingActivitiesImpl(trace); workflowTest.addActivitiesImplementation(activities); workflowTest.addWorkflowImplementationType(BookingWorkflowImpl.class); } @After public void tearDown() throws Exception { trace = null; } @Test public void testReserveBoth() { BookingWorkflowClient workflow = workflowFactory.getClient(); Promise<Void> booked = workflow.makeBooking(123, 345, true, true); List<String> expected = new ArrayList<String>(); expected.add("reserveCar-123"); JUnit Integration API Version 2021-04-28 124 AWS Flow Framework for Java Developer Guide expected.add("reserveAirline-123"); expected.add("sendConfirmation-345"); AsyncAssert.assertEqualsWaitFor("invalid booking", expected, trace, booked); } } You can also specify a separate task list for each activity implementation that you add to WorkflowTest. For example, if you have a workflow implementation that schedules activities in host-specific task lists, then you can register the activity in the task list of each host: for (int i = 0; i < 10; i++) { String hostname = "host" + i; workflowTest.addActivitiesImplementation(hostname, new ImageProcessingActivities(hostname)); } Notice that the code in the @Test is asynchronous. Therefore, you should use the asynchronous workflow client to start an execution. In order to verify the results of your test, an AsyncAssert help class is also provided. This class allows you to wait for promises to become ready before verifying results. In this example, we wait for the result of the workflow execution to be ready before verifying the test output. If you are using Spring, then the SpringWorkflowTest class can be used instead of the WorkflowTest class. SpringWorkflowTest provides properties that you can use to configure activity and workflow implementations easily through Spring configuration. Just like the Spring- aware workers, you should use the WorkflowScope to configure workflow implementation beans. This ensures that a new workflow implementation bean is created for every decision task. Make sure to configure these beans with the scoped-proxy proxy-target-class setting set to false. See the Spring Integration section for more details. The example Spring configuration shown in the Spring Integration section can be changed to test the workflow using SpringWorkflowTest: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http:// www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans ht tp://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframe work.org/schema/aop/spring-aop-2.5.xsd JUnit Integration API Version 2021-04-28 125 AWS Flow Framework for Java Developer Guide http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- register custom workflow scope --> <bean class="org.springframework.beans.factory.config.CustomScopeConfigurer"> <property name="scopes"> <map> <entry key="workflow"> <bean class="com.amazonaws.services.simpleworkflow.flow.spring.WorkflowScope" /> </entry> </map> </property> </bean> <context:annotation-config /> <bean id="accesskeys" class="com.amazonaws.auth.BasicAWSCredentials"> <constructor-arg value="{AWS.Access.ID}" /> <constructor-arg value="{AWS.Secret.Key}" /> </bean> <bean id="clientConfiguration" class="com.amazonaws.ClientConfiguration"> <property name="socketTimeout" value="70000" /> </bean> <!-- Amazon SWF client --> <bean id="swfClient" class="com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClient"> <constructor-arg ref="accesskeys" /> <constructor-arg ref="clientConfiguration" /> <property name="endpoint" value="{service.url}" /> </bean> <!-- activities client --> <bean id="activitiesClient" class="aws.flow.sample.MyActivitiesClientImpl" scope="workflow"> </bean> <!-- workflow implementation --> <bean id="workflowImpl" class="aws.flow.sample.MyWorkflowImpl" scope="workflow"> <property name="client" ref="activitiesClient" /> <aop:scoped-proxy proxy-target-class="false" /> </bean> <!-- WorkflowTest --> JUnit Integration API Version 2021-04-28 126 AWS Flow Framework for Java <bean id="workflowTest" Developer Guide class="com.amazonaws.services.simpleworkflow.flow.junit.spring.SpringWorkflowTest"> <property name="workflowImplementations"> <list> <ref bean="workflowImpl" /> </list> </property> <property name="taskListActivitiesImplementationMap"> <map> <entry> <key> <value>list1</value> </key> <ref bean="activitiesImplHost1" /> </entry> </map> </property> </bean> </beans> Mocking Activity Implementations You may use the real activity implementations during testing, but if you want to unit test just the workflow logic, you should mock the activities. This can do this by providing a mock implementation of the activities interface to the WorkflowTest class. For example: @RunWith(FlowBlockJUnit4ClassRunner.class) public class BookingWorkflowTest { @Rule public WorkflowTest workflowTest = new WorkflowTest(); List<String> trace; private BookingWorkflowClientFactory workflowFactory = new BookingWorkflowClientFactoryImpl(); @Before public void setUp() throws Exception { trace = new ArrayList<String>(); // Create and register mock activity implementation to be used during test run BookingActivities activities = new BookingActivities() { JUnit Integration API Version 2021-04-28 127 AWS Flow Framework for Java @Override public void sendConfirmationActivity(int customerId) { trace.add("sendConfirmation-" + customerId); Developer Guide } @Override public void reserveCar(int requestId) { trace.add("reserveCar-" + requestId); }
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do this by providing a mock implementation of the activities interface to the WorkflowTest class. For example: @RunWith(FlowBlockJUnit4ClassRunner.class) public class BookingWorkflowTest { @Rule public WorkflowTest workflowTest = new WorkflowTest(); List<String> trace; private BookingWorkflowClientFactory workflowFactory = new BookingWorkflowClientFactoryImpl(); @Before public void setUp() throws Exception { trace = new ArrayList<String>(); // Create and register mock activity implementation to be used during test run BookingActivities activities = new BookingActivities() { JUnit Integration API Version 2021-04-28 127 AWS Flow Framework for Java @Override public void sendConfirmationActivity(int customerId) { trace.add("sendConfirmation-" + customerId); Developer Guide } @Override public void reserveCar(int requestId) { trace.add("reserveCar-" + requestId); } @Override public void reserveAirline(int requestId) { trace.add("reserveAirline-" + requestId); } }; workflowTest.addActivitiesImplementation(activities); workflowTest.addWorkflowImplementationType(BookingWorkflowImpl.class); } @After public void tearDown() throws Exception { trace = null; } @Test public void testReserveBoth() { BookingWorkflowClient workflow = workflowFactory.getClient(); Promise<Void> booked = workflow.makeBooking(123, 345, true, true); List<String> expected = new ArrayList<String>(); expected.add("reserveCar-123"); expected.add("reserveAirline-123"); expected.add("sendConfirmation-345"); AsyncAssert.assertEqualsWaitFor("invalid booking", expected, trace, booked); } } Alternatively, you can provide a mock implementation of the activities client and inject that into your workflow implementation. Test Context Objects If your workflow implementation depends on the framework context objects—for example, the DecisionContext—you don't have to do anything special to test such workflows. JUnit Integration API Version 2021-04-28 128 AWS Flow Framework for Java Developer Guide When a test is run through WorkflowTest, it automatically injects test context objects. When your workflow implementation accesses the context objects—for example, using DecisionContextProviderImpl—it will get the test implementation. You can manipulate these test context objects in your test code (@Test method) to create interesting test cases. For example, if your workflow creates a timer, you can make the timer fire by calling the clockAdvanceSeconds method on the WorkflowTest class to move the clock forward in time. You can also accelerate the clock to make timers fire earlier than they normally would using the ClockAccelerationCoefficient property on WorkflowTest. For example, if your workflow creates a timer for one hour, you can set the ClockAccelerationCoefficient to 60 to make the timer fire in one minute. By default, ClockAccelerationCoefficient is set to 1. For more details about the com.amazonaws.services.simpleworkflow.flow.test and com.amazonaws.services.simpleworkflow.flow.junit packages, see the AWS SDK for Java documentation. Error Handling Topics • TryCatchFinally Semantics • Cancellation • Nested TryCatchFinally The try/catch/finally construct in Java makes it simple to handle errors and is used ubiquitously. It allows you to associate error handlers to a block of code. Internally, this works by stuffing additional metadata about the error handlers on the call stack. When an exception is thrown, the runtime looks at the call stack for an associated error handler and invokes it; and if no appropriate error handler is found, it propagates the exception up the call chain. This works well for synchronous code, but handling errors in asynchronous and distributed programs poses additional challenges. Because an asynchronous call returns immediately, the caller isn't on the call stack when the asynchronous code executes. This means that unhandled exceptions in the asynchronous code can't be handled by the caller in the usual way. Typically, exceptions that originate in asynchronous code are handled by passing error state to a callback that is passed to the asynchronous method. Alternatively, if a Future<?> is being used, it reports an error when you try to access it. This is less than ideal because the code that receives the exception (the callback or code that uses the Future<?>) doesn't have the context of the original Error Handling API Version 2021-04-28 129 AWS Flow Framework for Java Developer Guide call and may not be able to handle the exception adequately. Furthermore, in a distributed asynchronous system, with components running concurrently, more than one error may occur simultaneously. These errors could be of different types and severities and need to be handled appropriately. Cleaning up resource after an asynchronous call is also difficult. Unlike synchronous code, you can't use try/catch/finally in the calling code to clean up resources because work initiated in the try block may still be ongoing when the finally block executes. The framework provides a mechanism that makes error handling in distributed asynchronous code similar to, and almost as simple as, Java's try/catch/finally. ImageProcessingActivitiesClient activitiesClient = new ImageProcessingActivitiesClientImpl(); public void createThumbnail(final String webPageUrl) { new TryCatchFinally() { @Override protected void doTry() throws Throwable { List<String> images = getImageUrls(webPageUrl); for (String image: images) { Promise<String> localImage = activitiesClient.downloadImage(image); Promise<String> thumbnailFile = activitiesClient.createThumbnail(localImage); activitiesClient.uploadImage(thumbnailFile); } } @Override protected void doCatch(Throwable e) throws Throwable { // Handle exception and rethrow failures LoggingActivitiesClient logClient = new LoggingActivitiesClientImpl(); logClient.reportError(e); throw new RuntimeException("Failed to process images", e); } @Override protected void doFinally() throws Throwable { activitiesClient.cleanUp(); Error Handling API Version 2021-04-28 130 AWS Flow Framework for Java Developer Guide } }; } The TryCatchFinally class and its variants, TryFinally and TryCatch, work similar to Java's try/catch/finally. Using it, you can
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new TryCatchFinally() { @Override protected void doTry() throws Throwable { List<String> images = getImageUrls(webPageUrl); for (String image: images) { Promise<String> localImage = activitiesClient.downloadImage(image); Promise<String> thumbnailFile = activitiesClient.createThumbnail(localImage); activitiesClient.uploadImage(thumbnailFile); } } @Override protected void doCatch(Throwable e) throws Throwable { // Handle exception and rethrow failures LoggingActivitiesClient logClient = new LoggingActivitiesClientImpl(); logClient.reportError(e); throw new RuntimeException("Failed to process images", e); } @Override protected void doFinally() throws Throwable { activitiesClient.cleanUp(); Error Handling API Version 2021-04-28 130 AWS Flow Framework for Java Developer Guide } }; } The TryCatchFinally class and its variants, TryFinally and TryCatch, work similar to Java's try/catch/finally. Using it, you can associate exception handlers to blocks of workflow code that may execute as asynchronous and remote tasks. The doTry() method is logically equivalent to the try block. The framework automatically executes the code in doTry(). A list of Promise objects can be passed to the constructor of TryCatchFinally. The doTry method will be executed when all Promise objects passed in to the constructor become ready. If an exception is raised by code that was asynchronously invoked from within doTry(), any pending work in doTry() is canceled and doCatch() is called to handle the exception. For instance, in the listing above, if downloadImage throws an exception, then createThumbnail and uploadImage will be canceled. Finally, doFinally() is called when all asynchronous work is done (completed, failed, or canceled). It can be used for resource cleanup. You can also nest these classes to suit your needs. When an exception is reported in doCatch(), the framework provides a complete logical call stack that includes asynchronous and remote calls. This can be helpful when debugging, especially if you have asynchronous methods calling other asynchronous methods. For example, an exception from downloadImage will produce an exception like this: RuntimeException: error downloading image at downloadImage(Main.java:35) at ---continuation---.(repeated:1) at errorHandlingAsync$1.doTry(Main.java:24) at ---continuation---.(repeated:1) … TryCatchFinally Semantics The execution of an AWS Flow Framework for Java program can be visualized as a tree of concurrently executing branches. A call to an asynchronous method, an activity, and TryCatchFinally itself creates a new branch in this tree of execution. For example, the image processing workflow can be viewed as the tree shown in the following figure. TryCatchFinally Semantics API Version 2021-04-28 131 AWS Flow Framework for Java Developer Guide An error in one branch of execution will cause the unwinding of that branch, just as an exception causes the unwinding of the call stack in a Java program. The unwinding keeps moving up the execution branch until either the error is handled or the root of the tree is reached, in which case the workflow execution is terminated. The framework reports errors that happen while processing tasks as exceptions. It associates the exception handlers (doCatch() methods) defined in TryCatchFinally with all tasks that are created by the code in the corresponding doTry(). If a task fails—for example, due to a timeout or an unhandled exception—then the appropriate exception will be raised and the corresponding doCatch() will be invoked to handle it. To accomplish this, the framework works in tandem with Amazon SWF to propagate remote errors and resurrects them as exceptions in the caller's context. Cancellation When an exception occurs in synchronous code, the control jumps directly to the catch block, skipping over any remaining code in the try block. For example: try { a(); b(); c(); } catch (Exception e) { e.printStackTrace(); } In this code, if b() throws an exception, then c() is never invoked. Compare that to a workflow: new TryCatch() { @Override protected void doTry() throws Throwable { Cancellation API Version 2021-04-28 132 AWS Flow Framework for Java activityA(); activityB(); activityC(); } @Override Developer Guide protected void doCatch(Throwable e) throws Throwable { e.printStackTrace(); } }; In this case, calls to activityA, activityB, and activityC all return successfully and result in the creation of three tasks that will be executed asynchronously. Let's say at a later time that the task for activityB results in an error. This error is recorded in the history by Amazon SWF. In order to handle this, the framework will first try to cancel all other tasks that originated within the scope of the same doTry(); in this case, activityA and activityC. When all such tasks complete (cancel, fail, or successfully complete), the appropriate doCatch() method will be invoked to handle the error. Unlike the synchronous example, where c() was never executed, activityC was invoked and a task was scheduled for execution; hence, the framework will make an attempt to cancel it, but there is no guarantee that it will be canceled. Cancellation can't be guaranteed because the activity may have already completed, may ignore the cancellation request, or may fail due to an error. However, the framework does provide the guarantee that doCatch() is called only after all tasks started from the corresponding doTry() have
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complete (cancel, fail, or successfully complete), the appropriate doCatch() method will be invoked to handle the error. Unlike the synchronous example, where c() was never executed, activityC was invoked and a task was scheduled for execution; hence, the framework will make an attempt to cancel it, but there is no guarantee that it will be canceled. Cancellation can't be guaranteed because the activity may have already completed, may ignore the cancellation request, or may fail due to an error. However, the framework does provide the guarantee that doCatch() is called only after all tasks started from the corresponding doTry() have completed. It also guarantees that doFinally() is called only after all tasks started from the doTry() and doCatch() have completed. If, for instance, the activities in the above example depend on each other, say activityB depends on activityA and activityC on activityB, then the cancellation of activityC will be immediate because it isn't scheduled in Amazon SWF until activityB completes: new TryCatch() { @Override protected void doTry() throws Throwable { Promise<Void> a = activityA(); Promise<Void> b = activityB(a); activityC(b); } @Override Cancellation API Version 2021-04-28 133 AWS Flow Framework for Java Developer Guide protected void doCatch(Throwable e) throws Throwable { e.printStackTrace(); } }; Activity Heartbeat The AWS Flow Framework for Java's cooperative cancellation mechanism allows in-flight activity tasks to be canceled gracefully. When cancellation is triggered, tasks that blocked or are waiting to be assigned to a worker are automatically canceled. If, however, a task is already assigned to a worker, the framework will request the activity to cancel. Your activity implementation must explicitly handle such cancellation requests. This is done by reporting heartbeat of your activity. Reporting heartbeat allows the activity implementation to report the progress of an ongoing activity task, which is useful for monitoring, and it lets the activity check for cancellation requests. The recordActivityHeartbeat method will throw a CancellationException if a cancellation has been requested. The activity implementation can catch this exception and act on the cancellation request, or it can ignore the request by swallowing the exception. In order to honor the cancellation request, the activity should perform the desired clean up, if any, and then rethrow CancellationException. When this exception is thrown from an activity implementation, the framework records that the activity task has been completed in canceled state. The following example shows an activity that downloads and processes images. It heartbeats after processing each image, and if cancellation is requested, it cleans up and rethrows the exception to acknowledge cancellation. @Override public void processImages(List<String> urls) { int imageCounter = 0; for (String url: urls) { imageCounter++; Image image = download(url); process(image); try { ActivityExecutionContext context = contextProvider.getActivityExecutionContext(); context.recordActivityHeartbeat(Integer.toString(imageCounter)); } catch(CancellationException ex) { cleanDownloadFolder(); Cancellation API Version 2021-04-28 134 AWS Flow Framework for Java throw ex; } } } Developer Guide Reporting activity heartbeat isn't required, but it is recommended if your activity is long running or may be performing expensive operations that you wish to be canceled under error conditions. You should call heartbeatActivityTask periodically from the activity implementation. If the activity times out, the ActivityTaskTimedOutException will be thrown and getDetails on the exception object will return the data passed to the last successful call to heartbeatActivityTask for the corresponding activity task. The workflow implementation may use this information to determine how much progress was made before the activity task was timed out. Note It isn't a good practice to heartbeat too frequently because Amazon SWF may throttle heartbeat requests. See the Amazon Simple Workflow Service Developer Guide for limits placed by Amazon SWF. Explicitly Canceling a Task Besides error conditions, there are other cases where you may explicitly cancel a task. For example, an activity to process payments using a credit card may need to be canceled if the user cancels the order. The framework allows you to explicitly cancel tasks created in the scope of a TryCatchFinally. In the following example, the payment task is canceled if a signal is received while the payment was being processed. public class OrderProcessorImpl implements OrderProcessor { private PaymentProcessorClientFactory factory = new PaymentProcessorClientFactoryImpl(); boolean processingPayment = false; private TryCatchFinally paymentTask = null; @Override public void processOrder(int orderId, final float amount) { paymentTask = new TryCatchFinally() { Cancellation API Version 2021-04-28 135 AWS Flow Framework for Java @Override protected void doTry() throws Throwable { processingPayment = true; Developer Guide PaymentProcessorClient paymentClient = factory.getClient(); paymentClient.processPayment(amount); } @Override protected void doCatch(Throwable e) throws Throwable { if (e instanceof CancellationException) { paymentClient.log("Payment canceled."); } else { throw e; } } @Override protected void doFinally() throws Throwable { processingPayment = false; } }; } @Override public void cancelPayment() { if (processingPayment) { paymentTask.cancel(null); } } } Receiving Notification of Canceled Tasks When a task is completed in canceled state, the framework informs the workflow logic by throwing a CancellationException. When
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{ Cancellation API Version 2021-04-28 135 AWS Flow Framework for Java @Override protected void doTry() throws Throwable { processingPayment = true; Developer Guide PaymentProcessorClient paymentClient = factory.getClient(); paymentClient.processPayment(amount); } @Override protected void doCatch(Throwable e) throws Throwable { if (e instanceof CancellationException) { paymentClient.log("Payment canceled."); } else { throw e; } } @Override protected void doFinally() throws Throwable { processingPayment = false; } }; } @Override public void cancelPayment() { if (processingPayment) { paymentTask.cancel(null); } } } Receiving Notification of Canceled Tasks When a task is completed in canceled state, the framework informs the workflow logic by throwing a CancellationException. When an activity completes in canceled state, a record is made in the history and the framework calls the appropriate doCatch() with a CancellationException. As shown in the previous example, when the payment processing task is canceled, the workflow receives a CancellationException. An unhandled CancellationException is propagated up the execution branch just like any other exception. However, the doCatch() method will receive the CancellationException Cancellation API Version 2021-04-28 136 AWS Flow Framework for Java Developer Guide only if there is no other exception in the scope; other exceptions are prioritized higher than cancellation. Nested TryCatchFinally You may nest TryCatchFinally's to suit your needs. Because each TryCatchFinally creates a new branch in the execution tree, you can create nested scopes. Exceptions in the parent scope will cause cancellation attempts of all tasks initiated by nested TryCatchFinally's within it. However, exceptions in a nested TryCatchFinally don't automatically propagate to the parent. If you wish to propagate an exception from a nested TryCatchFinally to its containing TryCatchFinally, you should rethrow the exception in doCatch(). In other words, only unhandled exceptions are bubbled up, just like Java's try/catch. If you cancel a nested TryCatchFinally by calling the cancel method, the nested TryCatchFinally will be canceled but the containing TryCatchFinally will not automatically get canceled. new TryCatch() { @Override protected void doTry() throws Throwable { activityA(); new TryCatch() { @Override protected void doTry() throws Throwable { activityB(); } @Override protected void doCatch(Throwable e) throws Throwable { reportError(e); } Nested TryCatchFinally API Version 2021-04-28 137 Developer Guide AWS Flow Framework for Java }; activityC(); } @Override protected void doCatch(Throwable e) throws Throwable { reportError(e); } }; Retry Failed Activities Activities sometimes fail for ephemeral reasons, such as a temporary loss of connectivity. At another time, the activity might succeed, so the appropriate way to handle activity failure is often to retry the activity, perhaps multiple times. There are a variety of strategies for retrying activities; the best one depends on the details of your workflow. The strategies fall into three basic categories: • The retry-until-success strategy simply keeps retrying the activity until it completes. • The exponential retry strategy increases the time interval between retry attempts exponentially until the activity completes or the process reaches a specified stopping point, such as a maximum number of attempts. • The custom retry strategy decides whether or how to retry the activity after each failed attempt. The following sections describe how to implement these strategies. The example workflow workers all use a single activity, unreliableActivity, which randomly does one of following: • Completes immediately • Fails intentionally by exceeding the timeout value • Fails intentionally by throwing IllegalStateException Retry-Until-Success Strategy The simplest retry strategy is to keep retrying the activity each time it fails until it eventually succeeds. The basic pattern is: Retry Failed Activities API Version 2021-04-28 138 AWS Flow Framework for Java Developer Guide 1. Implement a nested TryCatch or TryCatchFinally class in your workflow's entry point method. 2. Execute the activity in doTry 3. If the activity fails, the framework calls doCatch, which runs the entry point method again. 4. Repeat Steps 2 - 3 until the activity completes successfully. The following workflow implements the retry-until-success strategy. The workflow interface is implemented in RetryActivityRecipeWorkflow and has one method, runUnreliableActivityTillSuccess, which is the workflow's entry point. The workflow worker is implemented in RetryActivityRecipeWorkflowImpl, as follows: public class RetryActivityRecipeWorkflowImpl implements RetryActivityRecipeWorkflow { @Override public void runUnreliableActivityTillSuccess() { final Settable<Boolean> retryActivity = new Settable<Boolean>(); new TryCatch() { @Override protected void doTry() throws Throwable { Promise<Void> activityRanSuccessfully = client.unreliableActivity(); setRetryActivityToFalse(activityRanSuccessfully, retryActivity); } @Override protected void doCatch(Throwable e) throws Throwable { retryActivity.set(true); } }; restartRunUnreliableActivityTillSuccess(retryActivity); } @Asynchronous private void setRetryActivityToFalse( Promise<Void> activityRanSuccessfully, @NoWait Settable<Boolean> retryActivity) { retryActivity.set(false); } Retry-Until-Success Strategy API Version 2021-04-28 139 Developer Guide AWS Flow Framework for Java @Asynchronous private void restartRunUnreliableActivityTillSuccess( Settable<Boolean> retryActivity) { if (retryActivity.get()) { runUnreliableActivityTillSuccess(); } } } The workflow works as follows: 1. runUnreliableActivityTillSuccess creates a Settable<Boolean> object named retryActivity which is used to indicate whether the activity failed and should be retried. Settable<T> is derived from Promise<T> and works much the same way, but you set a Settable<T> object's value manually. 2. runUnreliableActivityTillSuccess implements an anonymous nested TryCatch class to handle any exceptions
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} }; restartRunUnreliableActivityTillSuccess(retryActivity); } @Asynchronous private void setRetryActivityToFalse( Promise<Void> activityRanSuccessfully, @NoWait Settable<Boolean> retryActivity) { retryActivity.set(false); } Retry-Until-Success Strategy API Version 2021-04-28 139 Developer Guide AWS Flow Framework for Java @Asynchronous private void restartRunUnreliableActivityTillSuccess( Settable<Boolean> retryActivity) { if (retryActivity.get()) { runUnreliableActivityTillSuccess(); } } } The workflow works as follows: 1. runUnreliableActivityTillSuccess creates a Settable<Boolean> object named retryActivity which is used to indicate whether the activity failed and should be retried. Settable<T> is derived from Promise<T> and works much the same way, but you set a Settable<T> object's value manually. 2. runUnreliableActivityTillSuccess implements an anonymous nested TryCatch class to handle any exceptions that are thrown by the unreliableActivity activity. For more discussion of how to handle exceptions thrown by asynchronous code, see Error Handling. 3. doTry executes the unreliableActivity activity, which returns a Promise<Void> object named activityRanSuccessfully. 4. doTry calls the asynchronous setRetryActivityToFalse method, which has two parameters: • activityRanSuccessfully takes the Promise<Void> object returned by the unreliableActivity activity. • retryActivity takes the retryActivity object. If unreliableActivity completes, activityRanSuccessfully becomes ready and setRetryActivityToFalse sets retryActivity to false. Otherwise, activityRanSuccessfully never becomes ready and setRetryActivityToFalse doesn't execute. 5. If unreliableActivity throws an exception, the framework calls doCatch and passes it the exception object. doCatch sets retryActivity to true. 6. runUnreliableActivityTillSuccess calls the asynchronous restartRunUnreliableActivityTillSuccess method and passes it the retryActivity object. Because retryActivity is a Promise<T> type, restartRunUnreliableActivityTillSuccess defers execution until retryActivity is ready, which occurs after TryCatch completes. Retry-Until-Success Strategy API Version 2021-04-28 140 AWS Flow Framework for Java Developer Guide 7. When retryActivity is ready, restartRunUnreliableActivityTillSuccess extracts the value. • If the value is false, the retry succeeded. restartRunUnreliableActivityTillSuccess doesn'thing and the retry sequence terminates. • If the value is true, the retry failed. restartRunUnreliableActivityTillSuccess calls runUnreliableActivityTillSuccess to execute the activity again. 8. Steps 1 - 7 repeat until unreliableActivity completes. Note doCatch doesn't handle the exception; it simply sets the retryActivity object to true to indicate that the activity failed. The retry is handled by the asynchronous restartRunUnreliableActivityTillSuccess method, which defers execution until TryCatch completes. The reason for this approach is that, if you retry an activity in doCatch, you can't cancel it. Retrying the activity in restartRunUnreliableActivityTillSuccess allows you to execute cancellable activities. Exponential Retry Strategy With the exponential retry strategy, the framework executes a failed activity again after a specified period of time, N seconds. If that attempt fails the framework executes the activity again after 2N seconds, and then 4N seconds and so on. Because the wait time can get quite large, you typically stop the retry attempts at some point rather than continuing indefinitely. The framework provides three ways to implement an exponential retry strategy: • The @ExponentialRetry annotation is the simplest approach, but you must set the retry configuration options at compile time. • The RetryDecorator class allows you to set retry configuration at run time and change it as needed. • The AsyncRetryingExecutor class allows you to set retry configuration at run time and change it as needed. In addition, the framework calls a user-implemented AsyncRunnable.run method to run each retry attempt. Exponential Retry Strategy API Version 2021-04-28 141 AWS Flow Framework for Java Developer Guide All approaches support the following configuration options, where time values are in seconds: • The initial retry wait time. • The back-off coefficient, which is used to compute the retry intervals, as follows: retryInterval = initialRetryIntervalSeconds * Math.pow(backoffCoefficient, numberOfTries - 2) The default value is 2.0. • The maximum number of retry attempts. The default value is unlimited. • The maximum retry interval. The default value is unlimited. • The expiration time. Retry attempts stop when the total duration of the process exceeds this value. The default value is unlimited. • The exceptions that will trigger the retry process. By default, every exception triggers the retry process. • The exceptions that will not trigger a retry attempt. By default, no exceptions are excluded. The following sections describe the various ways that you can implement an exponential retry strategy. Exponential Retry with @ExponentialRetry The simplest way to implement an exponential retry strategy for an activity is to apply an @ExponentialRetry annotation to the activity in the interface definition. If the activity fails, the framework handles the retry process automatically, based on the specified option values. The basic pattern is: 1. Apply @ExponentialRetry to the appropriate activities and specify the retry configuration. 2. If an annotated activity fails, the framework automatically retries the activity according to the configuration specified by the annotation's arguments. The ExponentialRetryAnnotationWorkflow workflow worker implements the exponential retry strategy by using an @ExponentialRetry annotation. It uses an unreliableActivity activity whose interface definition is implemented in ExponentialRetryAnnotationActivities, as follows: Exponential Retry Strategy API Version 2021-04-28 142 AWS Flow Framework for Java Developer Guide @Activities(version = "1.0") @ActivityRegistrationOptions( defaultTaskScheduleToStartTimeoutSeconds = 30, defaultTaskStartToCloseTimeoutSeconds = 30) public interface ExponentialRetryAnnotationActivities { @ExponentialRetry(
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based on the specified option values. The basic pattern is: 1. Apply @ExponentialRetry to the appropriate activities and specify the retry configuration. 2. If an annotated activity fails, the framework automatically retries the activity according to the configuration specified by the annotation's arguments. The ExponentialRetryAnnotationWorkflow workflow worker implements the exponential retry strategy by using an @ExponentialRetry annotation. It uses an unreliableActivity activity whose interface definition is implemented in ExponentialRetryAnnotationActivities, as follows: Exponential Retry Strategy API Version 2021-04-28 142 AWS Flow Framework for Java Developer Guide @Activities(version = "1.0") @ActivityRegistrationOptions( defaultTaskScheduleToStartTimeoutSeconds = 30, defaultTaskStartToCloseTimeoutSeconds = 30) public interface ExponentialRetryAnnotationActivities { @ExponentialRetry( initialRetryIntervalSeconds = 5, maximumAttempts = 5, exceptionsToRetry = IllegalStateException.class) public void unreliableActivity(); } The @ExponentialRetry options specify the following strategy: • Retry only if the activity throws IllegalStateException. • Use an initial wait time of 5 seconds. • No more than 5 retry attempts. The workflow interface is implemented in RetryWorkflow and has one method, process, which is the workflow's entry point. The workflow worker is implemented in ExponentialRetryAnnotationWorkflowImpl, as follows: public class ExponentialRetryAnnotationWorkflowImpl implements RetryWorkflow { public void process() { handleUnreliableActivity(); } public void handleUnreliableActivity() { client.unreliableActivity(); } } The workflow works as follows: 1. process runs the synchronous handleUnreliableActivity method. 2. handleUnreliableActivity executes the unreliableActivity activity. If the activity fails by throwing IllegalStateException, the framework automatically runs the retry strategy specified in ExponentialRetryAnnotationActivities. Exponential Retry Strategy API Version 2021-04-28 143 AWS Flow Framework for Java Developer Guide Exponential Retry with the RetryDecorator Class @ExponentialRetry is simple to use. However, the configuration is static and set at compile time, so the framework uses the same retry strategy every time the activity fails. You can implement a more flexible exponential retry strategy by using the RetryDecorator class, which allows you to specify the configuration at run time and change it as needed. The basic pattern is: 1. Create and configure an ExponentialRetryPolicy object that specifies the retry configuration. 2. Create a RetryDecorator object and pass the ExponentialRetryPolicy object from Step 1 to the constructor. 3. Apply the decorator object to the activity by passing the activity client's class name to the RetryDecorator object's decorate method. 4. Execute the activity. If the activity fails, the framework retries the activity according to the ExponentialRetryPolicy object's configuration. You can change the retry configuration as needed by modifying this object. Note The @ExponentialRetry annotation and the RetryDecorator class are mutually exclusive. You can't use RetryDecorator to dynamically override a retry policy specified by an @ExponentialRetry annotation. The following workflow implementation shows how to use the RetryDecorator class to implement an exponential retry strategy. It uses an unreliableActivity activity that doesn't have an @ExponentialRetry annotation. The workflow interface is implemented in RetryWorkflow and has one method, process, which is the workflow's entry point. The workflow worker is implemented in DecoratorRetryWorkflowImpl, as follows: public class DecoratorRetryWorkflowImpl implements RetryWorkflow { ... public void process() { long initialRetryIntervalSeconds = 5; int maximumAttempts = 5; ExponentialRetryPolicy retryPolicy = new ExponentialRetryPolicy( Exponential Retry Strategy API Version 2021-04-28 144 AWS Flow Framework for Java Developer Guide initialRetryIntervalSeconds).withMaximumAttempts(maximumAttempts); Decorator retryDecorator = new RetryDecorator(retryPolicy); client = retryDecorator.decorate(RetryActivitiesClient.class, client); handleUnreliableActivity(); } public void handleUnreliableActivity() { client.unreliableActivity(); } } The workflow works as follows: 1. process creates and configures an ExponentialRetryPolicy object by: • Passing the initial retry interval to the constructor. • Calling the object's withMaximumAttempts method to set the maximum number of attempts to 5. ExponentialRetryPolicy exposes other with objects that you can use to specify other configuration options. 2. process creates a RetryDecorator object named retryDecorator and passes the ExponentialRetryPolicy object from Step 1 to the constructor. 3. process applies the decorator to the activity by calling the retryDecorator.decorate method and passing it the activity client's class name. 4. handleUnreliableActivity executes the activity. If the activity fails, the framework retries it according to the configuration specified in Step 1. Note Several of the ExponentialRetryPolicy class's with methods have a corresponding set method that you can call to modify the corresponding configuration option at any time: setBackoffCoefficient, setMaximumAttempts, setMaximumRetryIntervalSeconds, and setMaximumRetryExpirationIntervalSeconds. Exponential Retry Strategy API Version 2021-04-28 145 AWS Flow Framework for Java Developer Guide Exponential Retry with the AsyncRetryingExecutor Class The RetryDecorator class provides more flexibility in configuring the retry process than @ExponentialRetry, but the framework still runs the retry attempts automatically, based on the ExponentialRetryPolicy object's current configuration. A more flexible approach is to use the AsyncRetryingExecutor class. In addition to allowing you to configure the retry process at run time, the framework calls a user-implemented AsyncRunnable.run method to run each retry attempt instead of simply executing the activity. The basic pattern is: 1. Create and configure an ExponentialRetryPolicy object to specify the retry configuration. 2. Create an AsyncRetryingExecutor object, and pass it the ExponentialRetryPolicy object and an instance of the workflow clock. 3. Implement an anonymous nested TryCatch or TryCatchFinally
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@ExponentialRetry, but the framework still runs the retry attempts automatically, based on the ExponentialRetryPolicy object's current configuration. A more flexible approach is to use the AsyncRetryingExecutor class. In addition to allowing you to configure the retry process at run time, the framework calls a user-implemented AsyncRunnable.run method to run each retry attempt instead of simply executing the activity. The basic pattern is: 1. Create and configure an ExponentialRetryPolicy object to specify the retry configuration. 2. Create an AsyncRetryingExecutor object, and pass it the ExponentialRetryPolicy object and an instance of the workflow clock. 3. Implement an anonymous nested TryCatch or TryCatchFinally class. 4. Implement an anonymous AsyncRunnable class and override the run method to implement custom code for running the activity. 5. Override doTry to call the AsyncRetryingExecutor object's execute method and pass it the AsyncRunnable class from Step 4. The AsyncRetryingExecutor object calls AsyncRunnable.run to run the activity. 6. If the activity fails, the AsyncRetryingExecutor object calls the AsyncRunnable.run method again, according to the retry policy specified in Step 1. The following workflow shows how to use the AsyncRetryingExecutor class to implement an exponential retry strategy. It uses the same unreliableActivity activity as the DecoratorRetryWorkflow workflow discussed earlier. The workflow interface is implemented in RetryWorkflow and has one method, process, which is the workflow's entry point. The workflow worker is implemented in AsyncExecutorRetryWorkflowImpl, as follows: public class AsyncExecutorRetryWorkflowImpl implements RetryWorkflow { private final RetryActivitiesClient client = new RetryActivitiesClientImpl(); private final DecisionContextProvider contextProvider = new DecisionContextProviderImpl(); private final WorkflowClock clock = contextProvider.getDecisionContext().getWorkflowClock(); public void process() { Exponential Retry Strategy API Version 2021-04-28 146 AWS Flow Framework for Java Developer Guide long initialRetryIntervalSeconds = 5; int maximumAttempts = 5; handleUnreliableActivity(initialRetryIntervalSeconds, maximumAttempts); } public void handleUnreliableActivity(long initialRetryIntervalSeconds, int maximumAttempts) { ExponentialRetryPolicy retryPolicy = new ExponentialRetryPolicy(initialRetryIntervalSeconds).withMaximumAttempts(maximumAttempts); final AsyncExecutor executor = new AsyncRetryingExecutor(retryPolicy, clock); new TryCatch() { @Override protected void doTry() throws Throwable { executor.execute(new AsyncRunnable() { @Override public void run() throws Throwable { client.unreliableActivity(); } }); } @Override protected void doCatch(Throwable e) throws Throwable { } }; } } The workflow works as follows: 1. process calls the handleUnreliableActivity method and passes it the configuration settings. 2. handleUnreliableActivity uses the configuration settings from Step 1 to create an ExponentialRetryPolicy object, retryPolicy. 3. handleUnreliableActivity creates an AsyncRetryExecutor object, executor, and passes the ExponentialRetryPolicy object from Step 2 and an instance of the workflow clock to the constructor 4. handleUnreliableActivity implements an anonymous nested TryCatch class and overrides the doTry and doCatch methods to run the retry attempts and handle any exceptions. Exponential Retry Strategy API Version 2021-04-28 147 AWS Flow Framework for Java Developer Guide 5. doTry creates an anonymous AsyncRunnable class and overrides the run method to implement custom code to execute unreliableActivity. For simplicity, run just executes the activity, but you can implement more sophisticated approaches as appropriate. 6. doTry calls executor.execute and passes it the AsyncRunnable object. execute calls the AsyncRunnable object's run method to run the activity. 7. If the activity fails, executor calls run again, according to the retryPolicy object configuration. For more discussion of how to use the TryCatch class to handle errors, see AWS Flow Framework for Java Exceptions. Custom Retry Strategy The most flexible approach to retrying failed activities is a custom strategy, which recursively calls an asynchronous method that runs the retry attempt, much like the retry-until-success strategy. However, instead of simply running the activity again, you implement custom logic that decides whether and how to run each successive retry attempt. The basic pattern is: 1. Create a Settable<T> status object, which is used to indicate whether the activity failed. 2. Implement a nested TryCatch or TryCatchFinally class. 3. doTry executes the activity. 4. If the activity fails, doCatch sets the status object to indicate that the activity failed. 5. Call an asynchronous failure handling method and pass it the status object. The method defers execution until TryCatch or TryCatchFinally completes. 6. The failure handling method decides whether to retry the activity, and if so, when. The following workflow shows how to implement a custom retry strategy. It uses the same unreliableActivity activity as the DecoratorRetryWorkflow and AsyncExecutorRetryWorkflow workflows. The workflow interface is implemented in RetryWorkflow and has one method, process, which is the workflow's entry point. The workflow worker is implemented in CustomLogicRetryWorkflowImpl, as follows: public class CustomLogicRetryWorkflowImpl implements RetryWorkflow { ... public void process() { callActivityWithRetry(); Custom Retry Strategy API Version 2021-04-28 148 AWS Flow Framework for Java } @Asynchronous public void callActivityWithRetry() { final Settable<Throwable> failure = new Settable<Throwable>(); Developer Guide new TryCatchFinally() { protected void doTry() throws Throwable { client.unreliableActivity(); } protected void doCatch(Throwable e) { failure.set(e); } protected void doFinally() throws Throwable { if (!failure.isReady()) { failure.set(null); } } }; retryOnFailure(failure); } @Asynchronous private void retryOnFailure(Promise<Throwable> failureP) { Throwable failure = failureP.get(); if (failure != null && shouldRetry(failure)) { callActivityWithRetry(); }
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point. The workflow worker is implemented in CustomLogicRetryWorkflowImpl, as follows: public class CustomLogicRetryWorkflowImpl implements RetryWorkflow { ... public void process() { callActivityWithRetry(); Custom Retry Strategy API Version 2021-04-28 148 AWS Flow Framework for Java } @Asynchronous public void callActivityWithRetry() { final Settable<Throwable> failure = new Settable<Throwable>(); Developer Guide new TryCatchFinally() { protected void doTry() throws Throwable { client.unreliableActivity(); } protected void doCatch(Throwable e) { failure.set(e); } protected void doFinally() throws Throwable { if (!failure.isReady()) { failure.set(null); } } }; retryOnFailure(failure); } @Asynchronous private void retryOnFailure(Promise<Throwable> failureP) { Throwable failure = failureP.get(); if (failure != null && shouldRetry(failure)) { callActivityWithRetry(); } } protected Boolean shouldRetry(Throwable e) { //custom logic to decide to retry the activity or not return true; } } The workflow works as follows: 1. process calls the asynchronous callActivityWithRetry method. 2. callActivityWithRetry creates a Settable<Throwable> object named failure which is used to indicate whether the activity has failed. Settable<T> is derived from Promise<T> and works much the same way, but you set a Settable<T> object's value manually. 3. callActivityWithRetry implements an anonymous nested TryCatchFinally class to handle any exceptions that are thrown by unreliableActivity. For more discussion of how to handle exceptions thrown by asynchronous code, see AWS Flow Framework for Java Exceptions. Custom Retry Strategy API Version 2021-04-28 149 AWS Flow Framework for Java Developer Guide 4. doTry executes unreliableActivity. 5. If unreliableActivity throws an exception, the framework calls doCatch and passes it the exception object. doCatch sets failure to the exception object, which indicates that the activity failed and puts the object in a ready state. 6. doFinally checks whether failure is ready, which will be true only if failure was set by doCatch. • If failure is ready, doFinally does nothing. • If failure isn't ready, the activity completed and doFinally sets failure to null. 7. callActivityWithRetry calls the asynchronous retryOnFailure method and passes it failure. Because failure is a Settable<T> type, callActivityWithRetry defers execution until failure is ready, which occurs after TryCatchFinally completes. 8. retryOnFailure gets the value from failure. • If failure is set to null, the retry attempt was successful. retryOnFailure does nothing, which terminates the retry process. • If failure is set to an exception object and shouldRetry returns true, retryOnFailure calls callActivityWithRetry to retry the activity. shouldRetry implements custom logic to decide whether to retry a failed activity. For simplicity, shouldRetry always returns true and retryOnFailure executes the activity immediately, but you can implement more sophisticated logic as needed. 9. Steps 2–8 repeat until unreliableActivity completes or shouldRetry decides to stop the process. Note doCatch doesn't handle the retry process; it simply sets failure to indicate that the activity failed. The retry process is handled by the asynchronous retryOnFailure method, which defers execution until TryCatch completes. The reason for this approach is that, if you retry an activity in doCatch, you can't cancel it. Retrying the activity in retryOnFailure allows you to execute cancellable activities. Custom Retry Strategy API Version 2021-04-28 150 AWS Flow Framework for Java Daemon Tasks Developer Guide The AWS Flow Framework for Java allows the marking of certain tasks as daemon. This allows you to create tasks that do some background work that should get canceled when all other work is done. For example, a health monitoring task should be canceled when the rest of the workflow is complete. You can accomplish this by setting the daemon flag on an asynchronous method or an instance of TryCatchFinally. In the following example, the asynchronous method monitorHealth() is marked as daemon. public class MyWorkflowImpl implements MyWorkflow { MyActivitiesClient activitiesClient = new MyActivitiesClientImpl(); @Override public void startMyWF(int a, String b) { activitiesClient.doUsefulWorkActivity(); monitorHealth(); } @Asynchronous(daemon=true) void monitorHealth(Promise<?>... waitFor) { activitiesClient.monitoringActivity(); } } In the above example, when doUsefulWorkActivity completes, monitoringHealth will be automatically canceled. This will in turn cancel the whole execution branch rooted at this asynchronous method. The semantics of cancellation are the same as in TryCatchFinally. Similarly, you can mark a TryCatchFinally daemon by passing a Boolean flag to the constructor. public class MyWorkflowImpl implements MyWorkflow { MyActivitiesClient activitiesClient = new MyActivitiesClientImpl(); @Override public void startMyWF(int a, String b) { activitiesClient.doUsefulWorkActivity(); new TryFinally(true) { @Override protected void doTry() throws Throwable { activitiesClient.monitoringActivity(); Daemon Tasks API Version 2021-04-28 151 AWS Flow Framework for Java } @Override protected void doFinally() throws Throwable { // clean up Developer Guide } }; } } A daemon task started within a TryCatchFinally is scoped to the context it is created in— that is, it will be scoped to either the doTry(), doCatch(), or doFinally() methods. For example, in the following example the startMonitoring asynchronous method is marked daemon and called from doTry(). The task created for it will be canceled as soon as the other tasks (doUsefulWorkActivity in this case) started within doTry() are complete. public class MyWorkflowImpl implements MyWorkflow { MyActivitiesClient
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151 AWS Flow Framework for Java } @Override protected void doFinally() throws Throwable { // clean up Developer Guide } }; } } A daemon task started within a TryCatchFinally is scoped to the context it is created in— that is, it will be scoped to either the doTry(), doCatch(), or doFinally() methods. For example, in the following example the startMonitoring asynchronous method is marked daemon and called from doTry(). The task created for it will be canceled as soon as the other tasks (doUsefulWorkActivity in this case) started within doTry() are complete. public class MyWorkflowImpl implements MyWorkflow { MyActivitiesClient activitiesClient = new MyActivitiesClientImpl(); @Override public void startMyWF(int a, String b) { new TryFinally() { @Override protected void doTry() throws Throwable { activitiesClient.doUsefulWorkActivity(); startMonitoring(); } @Override protected void doFinally() throws Throwable { // Clean up } }; } @Asynchronous(daemon = true) void startMonitoring(){ activitiesClient.monitoringActivity(); } Daemon Tasks API Version 2021-04-28 152 AWS Flow Framework for Java Developer Guide AWS Flow Framework for Java Replay Behavior This topic discusses examples of replay behavior, using the examples in the What is the AWS Flow Framework for Java? section. Both synchronous and asynchronous scenarios are discussed. Example 1: Synchronous Replay For an example of how replay works in a synchronous workflow, modify the HelloWorldWorkflow workflow and activity implementations by adding println calls within their respective implementations, as follows: public class GreeterWorkflowImpl implements GreeterWorkflow { ... public void greet() { System.out.println("greet executes"); Promise<String> name = operations.getName(); System.out.println("client.getName returns"); Promise<String> greeting = operations.getGreeting(name); System.out.println("client.greeting returns"); operations.say(greeting); System.out.println("client.say returns"); } } ************** public class GreeterActivitiesImpl implements GreeterActivities { public String getName() { System.out.println("activity.getName completes"); return "World"; } public String getGreeting(String name) { System.out.println("activity.getGreeting completes"); return "Hello " + name + "!"; } public void say(String what) { System.out.println(what); } } For details about the code, see HelloWorldWorkflow Application. The following is an edited version of the output, with comments that indicate the start of each replay episode. Replay Behavior API Version 2021-04-28 153 AWS Flow Framework for Java Developer Guide //Episode 1 greet executes client.getName returns client.greeting returns client.say returns activity.getName completes //Episode 2 greet executes client.getName returns client.greeting returns client.say returns activity.getGreeting completes //Episode 3 greet executes client.getName returns client.greeting returns client.say returns Hello World! //say completes //Episode 4 greet executes client.getName returns client.greeting returns client.say returns The replay process for this example works as follows: • The first episode schedules the getName activity task, which has no dependencies. • The second episode schedules the getGreeting activity task, which depends on getName. • The third episode schedules the say activity task, which depends on getGreeting. • The final episode schedules no additional tasks and finds no uncompleted activities, which terminates the workflow execution. Note The three activities client methods are called once for each episode. However, only one of those calls results in an activity task, so each task is performed only once. Example 1: Synchronous Replay API Version 2021-04-28 154 AWS Flow Framework for Java Developer Guide Example 2: Asynchronous Replay Similarly to the synchronous replay example, you can modify HelloWorldWorkflowAsync Application to see how an asynchronous replay works. It produces the following output: //Episode 1 greet executes client.name returns workflow.getGreeting returns client.say returns activity.getName completes //Episode 2 greet executes client.name returns workflow.getGreeting returns client.say returns workflow.getGreeting completes Hello World! //say completes //Episode 3 greet executes client.name returns workflow.getGreeting returns client.say returns workflow.getGreeting completes HelloWorldAsync uses three replay episodes because there are only two activities. The getGreeting activity was replaced by the getGreeting asynchronous workflow method, which doesn't initiate a replay episode when it completes. The first episode doesn't call getGreeting, because it depends on the completion of the name activity. However, after getName completes, replay calls getGreeting once for each succeeding episode. See Also • AWS Flow Framework Basic Concepts: Distributed Execution Example 2: Asynchronous Replay API Version 2021-04-28 155 AWS Flow Framework for Java Developer Guide Best Practices Use these best practices to make the most of the AWS Flow Framework for Java. Topics • Making Changes to Decider Code: Versioning and Feature Flags Making Changes to Decider Code: Versioning and Feature Flags This section shows how to avoid backwards-incompatible changes to a decider using two methods: • Versioning provides a basic solution. • Versioning with Feature Flags builds on the Versioning solution: No new version of the workflow is introduced, and there is no need to push new code to update the version. Before you try these solutions, familiarize yourself with the Example Scenario section which explains the causes and effects of backwards-incompatible decider changes. The Replay Process and Code Changes When an AWS Flow Framework for Java decider worker executes a decision task, it first must rebuild the current state of the execution before it can add steps to it. The decider does this using a process called replay. The
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solution. • Versioning with Feature Flags builds on the Versioning solution: No new version of the workflow is introduced, and there is no need to push new code to update the version. Before you try these solutions, familiarize yourself with the Example Scenario section which explains the causes and effects of backwards-incompatible decider changes. The Replay Process and Code Changes When an AWS Flow Framework for Java decider worker executes a decision task, it first must rebuild the current state of the execution before it can add steps to it. The decider does this using a process called replay. The replay process re-executes the decider code from the beginning, while simultaneously going through the history of events that have already occurred. Going through the event history allows the framework to react to signals or task completion and unblock Promise objects in the code. When the framework executes the decider code, it assigns an ID to each scheduled task (an activity, Lambda function, timer, child workflow, or outgoing signal) by incrementing a counter. The framework communicates this ID to Amazon SWF, and adds the ID to history events, such as ActivityTaskCompleted. For the replay process to succeed, it is important for the decider code to be deterministic, and to schedule the same tasks in the same order for every decision in every workflow execution. If you don't adhere to this requirement, the framework might, for example, fail to match the ID in an ActivityTaskCompleted event to an existing Promise object. Making Changes to Decider Code API Version 2021-04-28 156 AWS Flow Framework for Java Example Scenario Developer Guide There is a class of code changes considered to be backwards-incompatible. These changes include updates that modify the number, type, or order of the scheduled tasks. Consider the following example: You write decider code to schedule two timer tasks. You start an execution and run a decision. As a result, two timer tasks are scheduled, with IDs 1 and 2. If you update the decider code to schedule only one timer before the next decision to be executed, during the next decision task the framework will fail to replay the second TimerFired event, because ID 2 doesn't match any timer tasks that the code has produced. Scenario Outline The following outline shows the steps of this scenario. The final goal of the scenario is to migrate to a system that schedules only one timer but doesn't cause failures in executions started before the migration. 1. The Initial Decider Version a. Write the decider. b. Start the decider. c. The decider schedules two timers. d. The decider starts five executions. e. Stop the decider. 2. A Backwards-Incompatible Decider Change a. Modify the decider. b. Start the decider. c. The decider schedules one timer. d. The decider starts five executions. The following sections include examples of Java code that show how to implement this scenario. The code examples in the Solutions section show various ways to fix backwards-incompatible changes. Example Scenario API Version 2021-04-28 157 AWS Flow Framework for Java Developer Guide Note You can use the latest version of the AWS SDK for Java to run this code. Common Code The following Java code doesn't change between the examples in this scenario. SampleBase.java package sample; import java.util.ArrayList; import java.util.List; import java.util.UUID; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflow; import com.amazonaws.services.simpleworkflow.AmazonSimpleWorkflowClientBuilder; import com.amazonaws.services.simpleworkflow.flow.JsonDataConverter; import com.amazonaws.services.simpleworkflow.model.DescribeWorkflowExecutionRequest; import com.amazonaws.services.simpleworkflow.model.DomainAlreadyExistsException; import com.amazonaws.services.simpleworkflow.model.RegisterDomainRequest; import com.amazonaws.services.simpleworkflow.model.Run; import com.amazonaws.services.simpleworkflow.model.StartWorkflowExecutionRequest; import com.amazonaws.services.simpleworkflow.model.TaskList; import com.amazonaws.services.simpleworkflow.model.WorkflowExecution; import com.amazonaws.services.simpleworkflow.model.WorkflowExecutionDetail; import com.amazonaws.services.simpleworkflow.model.WorkflowType; public class SampleBase { protected String domain = "DeciderChangeSample"; protected String taskList = "DeciderChangeSample-" + UUID.randomUUID().toString(); protected AmazonSimpleWorkflow service = AmazonSimpleWorkflowClientBuilder.defaultClient(); { try { AmazonSimpleWorkflowClientBuilder.defaultClient().registerDomain(new RegisterDomainRequest().withName(domain).withDescription("desc").withWorkflowExecutionRetentionPeriodInDays("7")); } catch (DomainAlreadyExistsException e) { } } Example Scenario API Version 2021-04-28 158 AWS Flow Framework for Java Developer Guide protected List<WorkflowExecution> workflowExecutions = new ArrayList<>(); protected void startFiveExecutions(String workflow, String version, Object input) { for (int i = 0; i < 5; i++) { String id = UUID.randomUUID().toString(); Run startWorkflowExecution = service.startWorkflowExecution( new StartWorkflowExecutionRequest().withDomain(domain).withTaskList(new TaskList().withName(taskList)).withInput(new JsonDataConverter().toData(new Object[] { input })).withWorkflowId(id).withWorkflowType(new WorkflowType().withName(workflow).withVersion(version))); workflowExecutions.add(new WorkflowExecution().withWorkflowId(id).withRunId(startWorkflowExecution.getRunId())); sleep(1000); } } protected void printExecutionResults() { waitForExecutionsToClose(); System.out.println("\nResults:"); for (WorkflowExecution wid : workflowExecutions) { WorkflowExecutionDetail details = service.describeWorkflowExecution(new DescribeWorkflowExecutionRequest().withDomain(domain).withExecution(wid)); System.out.println(wid.getWorkflowId() + " " + details.getExecutionInfo().getCloseStatus()); } } protected void waitForExecutionsToClose() { loop: while (true) { for (WorkflowExecution wid : workflowExecutions) { WorkflowExecutionDetail details = service.describeWorkflowExecution(new DescribeWorkflowExecutionRequest().withDomain(domain).withExecution(wid)); if ("OPEN".equals(details.getExecutionInfo().getExecutionStatus())) { sleep(1000); continue loop; } } return; } } protected void sleep(int millis) { Example Scenario API Version 2021-04-28 159 AWS Flow Framework for Java try { Thread.sleep(millis); } catch (InterruptedException e) { Thread.currentThread().interrupt(); Developer Guide } } } Input.java package sample; public class Input { private Boolean skipSecondTimer; public Input() { } public Input(Boolean skipSecondTimer) { this.skipSecondTimer = skipSecondTimer; } public Boolean getSkipSecondTimer() { return skipSecondTimer != null && skipSecondTimer; } public Input setSkipSecondTimer(Boolean skipSecondTimer) { this.skipSecondTimer = skipSecondTimer; return this; } } Writing Initial Decider Code The following
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: workflowExecutions) { WorkflowExecutionDetail details = service.describeWorkflowExecution(new DescribeWorkflowExecutionRequest().withDomain(domain).withExecution(wid)); if ("OPEN".equals(details.getExecutionInfo().getExecutionStatus())) { sleep(1000); continue loop; } } return; } } protected void sleep(int millis) { Example Scenario API Version 2021-04-28 159 AWS Flow Framework for Java try { Thread.sleep(millis); } catch (InterruptedException e) { Thread.currentThread().interrupt(); Developer Guide } } } Input.java package sample; public class Input { private Boolean skipSecondTimer; public Input() { } public Input(Boolean skipSecondTimer) { this.skipSecondTimer = skipSecondTimer; } public Boolean getSkipSecondTimer() { return skipSecondTimer != null && skipSecondTimer; } public Input setSkipSecondTimer(Boolean skipSecondTimer) { this.skipSecondTimer = skipSecondTimer; return this; } } Writing Initial Decider Code The following is the initial Java code of the decider. It's registered as version 1 and it schedules two five-second timer tasks. InitialDecider.java package sample.v1; Example Scenario API Version 2021-04-28 160 AWS Flow Framework for Java Developer Guide import com.amazonaws.services.simpleworkflow.flow.DecisionContext; import com.amazonaws.services.simpleworkflow.flow.DecisionContextProviderImpl; import com.amazonaws.services.simpleworkflow.flow.WorkflowClock; import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; import com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; import sample.Input; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 60, defaultTaskStartToCloseTimeoutSeconds = 5) public interface Foo { @Execute(version = "1") public void sample(Input input); public static class Impl implements Foo { private DecisionContext decisionContext = new DecisionContextProviderImpl().getDecisionContext(); private WorkflowClock clock = decisionContext.getWorkflowClock(); @Override public void sample(Input input) { System.out.println("Decision (V1) WorkflowId: " + decisionContext.getWorkflowContext().getWorkflowExecution().getWorkflowId()); clock.createTimer(5); clock.createTimer(5); } } } Simulating a Backwards-Incompatible Change The following modified Java code of the decider is a good example of a backwards-incompatible change. The code is still registered as version 1, but schedules only one timer. ModifiedDecider.java Example Scenario API Version 2021-04-28 161 AWS Flow Framework for Java Developer Guide package sample.v1.modified; import com.amazonaws.services.simpleworkflow.flow.DecisionContext; import com.amazonaws.services.simpleworkflow.flow.DecisionContextProviderImpl; import com.amazonaws.services.simpleworkflow.flow.WorkflowClock; import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; import com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; import sample.Input; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 60, defaultTaskStartToCloseTimeoutSeconds = 5) public interface Foo { @Execute(version = "1") public void sample(Input input); public static class Impl implements Foo { private DecisionContext decisionContext = new DecisionContextProviderImpl().getDecisionContext(); private WorkflowClock clock = decisionContext.getWorkflowClock(); @Override public void sample(Input input) { System.out.println("Decision (V1 modified) WorkflowId: " + decisionContext.getWorkflowContext().getWorkflowExecution().getWorkflowId()); clock.createTimer(5); } } } The following Java code allows you to simulate the problem of making backwards-incompatible changes by running the modified decider. RunModifiedDecider.java package sample; Example Scenario API Version 2021-04-28 162 AWS Flow Framework for Java Developer Guide import com.amazonaws.services.simpleworkflow.flow.WorkflowWorker; public class BadChange extends SampleBase { public static void main(String[] args) throws Exception { new BadChange().run(); } public void run() throws Exception { // Start the first version of the decider WorkflowWorker before = new WorkflowWorker(service, domain, taskList); before.addWorkflowImplementationType(sample.v1.Foo.Impl.class); before.start(); // Start a few executions startFiveExecutions("Foo.sample", "1", new Input()); // Stop the first decider worker and wait a few seconds // for its pending pollers to match and return before.suspendPolling(); sleep(2000); // At this point, three executions are still open, with more decisions to make // Start the modified version of the decider WorkflowWorker after = new WorkflowWorker(service, domain, taskList); after.addWorkflowImplementationType(sample.v1.modified.Foo.Impl.class); after.start(); // Start a few more executions startFiveExecutions("Foo.sample", "1", new Input()); printExecutionResults(); } } When you run the program, the three executions that fail are those that started under the initial version of the decider and continued after the migration. Example Scenario API Version 2021-04-28 163 AWS Flow Framework for Java Solutions Developer Guide You can use the following solutions to avoid backwards-incompatible changes. For more information, see Making Changes to Decider Code and Example Scenario. Using Versioning In this solution, you copy the decider to a new class, modify the decider, and then register the decider under a new workflow version. VersionedDecider.java package sample.v2; import com.amazonaws.services.simpleworkflow.flow.DecisionContext; import com.amazonaws.services.simpleworkflow.flow.DecisionContextProviderImpl; import com.amazonaws.services.simpleworkflow.flow.WorkflowClock; import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; import com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; import sample.Input; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 60, defaultTaskStartToCloseTimeoutSeconds = 5) public interface Foo { @Execute(version = "2") public void sample(Input input); public static class Impl implements Foo { private DecisionContext decisionContext = new DecisionContextProviderImpl().getDecisionContext(); private WorkflowClock clock = decisionContext.getWorkflowClock(); @Override public void sample(Input input) { System.out.println("Decision (V2) WorkflowId: " + decisionContext.getWorkflowContext().getWorkflowExecution().getWorkflowId()); clock.createTimer(5); Solutions API Version 2021-04-28 164 AWS Flow Framework for Java } } } Developer Guide In the updated Java code, the second decider worker runs both versions of the workflow, allowing in-flight executions to continue to execute independently of the changes in version 2. RunVersionedDecider.java package sample; import com.amazonaws.services.simpleworkflow.flow.WorkflowWorker; public class VersionedChange extends SampleBase { public static void main(String[] args) throws Exception { new VersionedChange().run(); } public void run() throws Exception { // Start the first version of the decider, with workflow version 1 WorkflowWorker before = new WorkflowWorker(service, domain, taskList); before.addWorkflowImplementationType(sample.v1.Foo.Impl.class); before.start(); // Start a few executions with version 1 startFiveExecutions("Foo.sample", "1", new Input()); // Stop the first decider worker and wait a few seconds // for its pending pollers to match and return before.suspendPolling(); sleep(2000); // At this point, three executions are still open, with more decisions to make // Start a worker with both the previous version of the decider (workflow version 1) // and the modified code (workflow version 2) WorkflowWorker after = new WorkflowWorker(service, domain, taskList); after.addWorkflowImplementationType(sample.v1.Foo.Impl.class); after.addWorkflowImplementationType(sample.v2.Foo.Impl.class); Solutions API
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first version of the decider, with workflow version 1 WorkflowWorker before = new WorkflowWorker(service, domain, taskList); before.addWorkflowImplementationType(sample.v1.Foo.Impl.class); before.start(); // Start a few executions with version 1 startFiveExecutions("Foo.sample", "1", new Input()); // Stop the first decider worker and wait a few seconds // for its pending pollers to match and return before.suspendPolling(); sleep(2000); // At this point, three executions are still open, with more decisions to make // Start a worker with both the previous version of the decider (workflow version 1) // and the modified code (workflow version 2) WorkflowWorker after = new WorkflowWorker(service, domain, taskList); after.addWorkflowImplementationType(sample.v1.Foo.Impl.class); after.addWorkflowImplementationType(sample.v2.Foo.Impl.class); Solutions API Version 2021-04-28 165 AWS Flow Framework for Java after.start(); Developer Guide // Start a few more executions with version 2 startFiveExecutions("Foo.sample", "2", new Input()); printExecutionResults(); } } When you run the program, all executions complete successfully. Using Feature Flags Another solution to backwards-compatibility issues is to branch code to support two implementations in the same class is to branch based on input data instead of workflow versions. When you take this approach, you add fields to (or modify existing fields of) your input objects every time you introduce sensitive changes. For executions that start before the migration, the input object won't have the field (or will have a different value). Thus, you don't have to increase the version number. Note If you add new fields, ensure that the JSON deserialization process is backwards- compatible. Objects serialized before the introduction of the field should still successfully deserialize after the migration. Because JSON sets a null value whenever a field is missing, always use boxed types (Boolean instead of boolean) and handle the cases where the value is null. FeatureFlagDecider.java package sample.v1.featureflag; import com.amazonaws.services.simpleworkflow.flow.DecisionContext; import com.amazonaws.services.simpleworkflow.flow.DecisionContextProviderImpl; import com.amazonaws.services.simpleworkflow.flow.WorkflowClock; import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; Solutions API Version 2021-04-28 166 AWS Flow Framework for Java import Developer Guide com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; import sample.Input; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 60, defaultTaskStartToCloseTimeoutSeconds = 5) public interface Foo { @Execute(version = "1") public void sample(Input input); public static class Impl implements Foo { private DecisionContext decisionContext = new DecisionContextProviderImpl().getDecisionContext(); private WorkflowClock clock = decisionContext.getWorkflowClock(); @Override public void sample(Input input) { System.out.println("Decision (V1 feature flag) WorkflowId: " + decisionContext.getWorkflowContext().getWorkflowExecution().getWorkflowId()); clock.createTimer(5); if (!input.getSkipSecondTimer()) { clock.createTimer(5); } } } } In the updated Java code, the code for both versions of the workflow is still registered for version 1. However, after the migration, new executions start with the skipSecondTimer field of the input data set to true. RunFeatureFlagDecider.java package sample; import com.amazonaws.services.simpleworkflow.flow.WorkflowWorker; public class FeatureFlagChange extends SampleBase { Solutions API Version 2021-04-28 167 AWS Flow Framework for Java Developer Guide public static void main(String[] args) throws Exception { new FeatureFlagChange().run(); } public void run() throws Exception { // Start the first version of the decider WorkflowWorker before = new WorkflowWorker(service, domain, taskList); before.addWorkflowImplementationType(sample.v1.Foo.Impl.class); before.start(); // Start a few executions startFiveExecutions("Foo.sample", "1", new Input()); // Stop the first decider worker and wait a few seconds // for its pending pollers to match and return before.suspendPolling(); sleep(2000); // At this point, three executions are still open, with more decisions to make // Start a new version of the decider that introduces a change // while preserving backwards compatibility based on input fields WorkflowWorker after = new WorkflowWorker(service, domain, taskList); after.addWorkflowImplementationType(sample.v1.featureflag.Foo.Impl.class); after.start(); // Start a few more executions and enable the new feature through the input data startFiveExecutions("Foo.sample", "1", new Input().setSkipSecondTimer(true)); printExecutionResults(); } } When you run the program, all executions complete successfully. Solutions API Version 2021-04-28 168 AWS Flow Framework for Java Developer Guide Troubleshooting and debugging tips for AWS Flow Framework for Java Topics • Compilation errors • Unknown resource fault • Exceptions when calling get() on a Promise • Nondeterministic workflows • Problems due to versioning • Troubleshooting and debugging a workflow execution • Lost tasks • Validation failure due to API parameter length constraints This section describes some common pitfalls that you might run into while developing workflows using AWS Flow Framework for Java. It also provides some tips to help you diagnose and debug problems. Compilation errors If you are using the AspectJ compile time weaving option, you may run into compile time errors in which the compiler isn't able to find the generated client classes for your workflow and activities. The likely cause of such compilation errors is that the AspectJ builder ignored the generated clients during compilation. You can fix this issue by removing AspectJ capability from the project and re- enabling it. Note that you will need to do this every time your workflow or activities interfaces change. Because of this issue, we recommend that you use the load time weaving option instead. See the section Setting up the AWS Flow Framework for Java for more details. Unknown resource fault Amazon SWF returns unknown resource fault when you try to perform an operation on a resource that isn't available. The
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cause of such compilation errors is that the AspectJ builder ignored the generated clients during compilation. You can fix this issue by removing AspectJ capability from the project and re- enabling it. Note that you will need to do this every time your workflow or activities interfaces change. Because of this issue, we recommend that you use the load time weaving option instead. See the section Setting up the AWS Flow Framework for Java for more details. Unknown resource fault Amazon SWF returns unknown resource fault when you try to perform an operation on a resource that isn't available. The common causes for this fault are: • You configure a worker with a domain that doesn't exist. To fix this, first register the domain using the Amazon SWF console or the Amazon SWF service API. Compilation errors API Version 2021-04-28 169 AWS Flow Framework for Java Developer Guide • You try to create workflow execution or activity tasks of types that have not been registered. This can happen if you try to create the workflow execution before the workers have been run. Because workers register their types when they are run for the first time, you must run them at least once before attempting to start executions (or manually register the types using the Console or the service API). Note that once types have been registered, you can create executions even if no worker is running. • A worker attempts to complete a task that has already timed out. For example, if a worker takes too long to process a task and exceeds a timeout, it will get an UnknownResource fault when it attempts to complete or fail the task. The AWS Flow Framework workers will continue to poll Amazon SWF and process additional tasks. However, you should consider adjusting the timeout. Adjusting the timeout requires that you register a new version of the activity type. Exceptions when calling get() on a Promise Unlike Java Future, Promise is a non-blocking construct and calling get() on a Promise that isn't ready yet will throw an exception instead of blocking. The correct way to use a Promise is to pass it to an asynchronous method (or a task) and access its value in the asynchronous method. AWS Flow Framework for Java ensures that an asynchronous method is called only when all Promise arguments passed to it have become ready. If you believe your code is correct or if you run into this while running one of the AWS Flow Framework samples, then it is most likely due to AspectJ not being properly configured. For details, see the section Setting up the AWS Flow Framework for Java. Nondeterministic workflows As described in the section Nondeterminism, the implementation of your workflow must be deterministic. Some common mistakes that can lead to nondeterminism are use of system clock, use of random numbers, and generation of GUIDs. Because these constructs may return different values at different times, the control flow of your workflow may take different paths each time it is executed (see the sections AWS Flow Framework Basic Concepts: Distributed Execution and Understanding a Task in AWS Flow Framework for Java for details). If the framework detects nondeterminism while executing the workflow, an exception will be thrown. Exceptions when calling get() on a Promise API Version 2021-04-28 170 AWS Flow Framework for Java Developer Guide Problems due to versioning When you implement a new version of your workflow or activity—for instance, when you add a new feature—you should increase the version of the type by using the appropriate annotation: @Workflow, @Activites, or @Activity. When new versions of a workflow are deployed, often times you will have executions of the existing version that are already running. Therefore, you need to make sure that workers with the appropriate version of your workflow and activities get the tasks. You can accomplish this by using a different set of task lists for each version. For example, you can append the version number to the name of the task list. This ensures that tasks belonging to different versions of the workflow and activities are assigned to the appropriate workers. Troubleshooting and debugging a workflow execution The first step in troubleshooting a workflow execution is to use the Amazon SWF console to look at the workflow history. The workflow history is a complete and authoritative record of all the events that changed the execution state of the workflow execution. This history is maintained by Amazon SWF and is invaluable for diagnosing problems. The Amazon SWF console enables you to search for workflow executions and drill down into individual history events. AWS Flow Framework provides a WorkflowReplayer class that you can use to replay a workflow execution locally and debug it. Using this class, you can debug closed and running workflow executions.
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a workflow execution is to use the Amazon SWF console to look at the workflow history. The workflow history is a complete and authoritative record of all the events that changed the execution state of the workflow execution. This history is maintained by Amazon SWF and is invaluable for diagnosing problems. The Amazon SWF console enables you to search for workflow executions and drill down into individual history events. AWS Flow Framework provides a WorkflowReplayer class that you can use to replay a workflow execution locally and debug it. Using this class, you can debug closed and running workflow executions. WorkflowReplayer relies on the history stored in Amazon SWF to perform the replay. You can point it to a workflow execution in your Amazon SWF account or provide it with the history events (for example, you can retrieve the history from Amazon SWF and serialize it locally for later use). When you replay a workflow execution using the WorkflowReplayer, it doesn't impact the workflow execution running in your account. The replay is done completely on the client. You can debug the workflow, create breakpoints, and step into code using your debugging tools as usual. If you are using Eclipse, consider adding step filters to filter AWS Flow Framework packages. For example, the following code snippet can be used to replay a workflow execution: String workflowId = "testWorkflow"; String runId = "<run id>"; Class<HelloWorldImpl> workflowImplementationType = HelloWorldImpl.class; WorkflowExecution workflowExecution = new WorkflowExecution(); workflowExecution.setWorkflowId(workflowId); workflowExecution.setRunId(runId); Problems due to versioning API Version 2021-04-28 171 AWS Flow Framework for Java Developer Guide WorkflowReplayer<HelloWorldImpl> replayer = new WorkflowReplayer<HelloWorldImpl>( swfService, domain, workflowExecution, workflowImplementationType); System.out.println("Beginning workflow replay for " + workflowExecution); Object workflow = replayer.loadWorkflow(); System.out.println("Workflow implementation object:"); System.out.println(workflow); System.out.println("Done workflow replay for " + workflowExecution); AWS Flow Framework also allows you to get an asynchronous thread dump of your workflow execution. This thread dump gives you the call stacks of all open asynchronous tasks. This information can be useful to determine which tasks in the execution are pending and possibly stuck. For example: String workflowId = "testWorkflow"; String runId = "<run id>"; Class<HelloWorldImpl> workflowImplementationType = HelloWorldImpl.class; WorkflowExecution workflowExecution = new WorkflowExecution(); workflowExecution.setWorkflowId(workflowId); workflowExecution.setRunId(runId); WorkflowReplayer<HelloWorldImpl> replayer = new WorkflowReplayer<HelloWorldImpl>( swfService, domain, workflowExecution, workflowImplementationType); try { String flowThreadDump = replayer.getAsynchronousThreadDumpAsString(); System.out.println("Workflow asynchronous thread dump:"); System.out.println(flowThreadDump); } catch (WorkflowException e) { System.out.println("No asynchronous thread dump available as workflow has failed: " + e); } Lost tasks Sometimes you may shut down workers and start new ones in quick succession only to discover that tasks get delivered to the old workers. This can happen due to race conditions in the system, which is distributed across several processes. The problem can also appear when you are running unit tests in a tight loop. Stopping a test in Eclipse can also sometimes cause this because shutdown handlers may not get called. Lost tasks API Version 2021-04-28 172 AWS Flow Framework for Java Developer Guide In order to make sure that the problem is in fact due to old workers getting tasks, you should look at the workflow history to determine which process received the task that you expected the new worker to receive. For example, the DecisionTaskStarted event in history contains the identity of the workflow worker that received the task. The id used by the Flow Framework is of the form: {processId}@{host name}. For instance, following are the details of the DecisionTaskStarted event in the Amazon SWF console for a sample execution: Event Timestamp Mon Feb 20 11:52:40 GMT-800 2012 Identity 2276@ip-0A6C1DF5 Scheduled Event Id 33 In order to avoid this situation, use different task lists for each test. Also, consider adding a delay between shutting down old workers and starting new ones. Validation failure due to API parameter length constraints Amazon SWF enforces length constraints on API parameters. You will receive an HTTP 400 error if your workflow or activity implementation exceeds the constraints. For example, when calling recordActivityHeartbeat on ActivityExecutionContext to send a heartbeat for a running activity, the string must not be longer than 2048 characters. Another common scenario is when an activity fails due to an exception. The framework reports an activity failure to Amazon SWF by calling RespondActivityTaskFailed with the serialized exception as details. The API call will report a 400 error if the serialized exception has a length greater than 32,768 bytes. To mitigate this situation, you can truncate the exception message or the causes to conform to the length constraint. Validation failure due to API parameter length constraints API Version 2021-04-28 173 AWS Flow Framework for Java Developer Guide AWS Flow Framework for Java Reference Topics • AWS Flow Framework for Java Annotations • AWS Flow Framework for Java Exceptions • AWS Flow Framework for Java Packages AWS Flow Framework for Java Annotations Topics • @Activities • @Activity • @ActivityRegistrationOptions • @Asynchronous • @Execute
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call will report a 400 error if the serialized exception has a length greater than 32,768 bytes. To mitigate this situation, you can truncate the exception message or the causes to conform to the length constraint. Validation failure due to API parameter length constraints API Version 2021-04-28 173 AWS Flow Framework for Java Developer Guide AWS Flow Framework for Java Reference Topics • AWS Flow Framework for Java Annotations • AWS Flow Framework for Java Exceptions • AWS Flow Framework for Java Packages AWS Flow Framework for Java Annotations Topics • @Activities • @Activity • @ActivityRegistrationOptions • @Asynchronous • @Execute • @ExponentialRetry • @GetState • @ManualActivityCompletion • @Signal • @SkipRegistration • @Wait and @NoWait • @Workflow • @WorkflowRegistrationOptions @Activities This annotation can be used on an interface to declare a set of activity types. Each method in an interface annotated with this annotation represents an activity type. An interface can't have both @Workflow and @Activities annotations- The following parameters can be specified on this annotation: Annotations API Version 2021-04-28 174 AWS Flow Framework for Java activityNamePrefix Developer Guide Specifies the prefix of the name of the activity types declared in the interface. If set to an empty string (which is the default), the name of the interface followed by '.' is used as the prefix. version Specifies the default version of the activity types declared in the interface. The default value is 1.0. dataConverter Specifies the type of the DataConverter to use for serializing/deserializing data when creating tasks of this activity type and its results. Set to NullDataConverter by default, which indicates that the JsonDataConverter should be used. @Activity This annotation can be used on methods within an interface annotated with @Activities. The following parameters can be specified on this annotation: name Specifies the name of the activity type. The default is an empty string, which indicates that the default prefix and the activity method name should be used to determine the name of the activity type (which is of the form {prefix}{name}). Note that when you specify a name in an @Activity annotation, the framework will not automatically prepend a prefix to it. You are free to use your own naming scheme. version Specifies the version of the activity type. This overrides the default version specified in the @Activities annotation on the containing interface. The default is an empty string. @ActivityRegistrationOptions Specifies the registration options of an activity type. This annotation can be used on an interface annotated with @Activities or the methods within. If specified in both places, then the annotation used on the method takes effect. @Activity API Version 2021-04-28 175 AWS Flow Framework for Java Developer Guide The following parameters can be specified on this annotation: defaultTasklist Specifies the default task list to be registered with Amazon SWF for this activity type. This default can be overridden when calling the activity method on the generated client using the ActivitySchedulingOptions parameter. Set to USE_WORKER_TASK_LIST by default. This is a special value which indicates that the task list used by the worker, which is performing the registration, should be used. defaultTaskScheduleToStartTimeoutSeconds Specifies the defaultTaskScheduleToStartTimeout registered with Amazon SWF for this activity type. This is the maximum time a task of this activity type is allowed to wait before it is assigned to a worker. See the Amazon Simple Workflow Service API Reference for more details. defaultTaskHeartbeatTimeoutSeconds Specifies the defaultTaskHeartbeatTimeout registered with Amazon SWF for this activity type. Activity workers must provide heartbeat within this duration; otherwise, the task will be timed out. Set to -1 by default, which is a special value that indicates this timeout should be disabled. See the Amazon Simple Workflow Service API Reference for more details. defaultTaskStartToCloseTimeoutSeconds Specifies the defaultTaskStartToCloseTimeout registered with Amazon SWF for this activity type. This timeout determines the maximum time a worker can take to process an activity task of this type. See the Amazon Simple Workflow Service API Reference for more details. defaultTaskScheduleToCloseTimeoutSeconds Specifies the defaultScheduleToCloseTimeout registered with Amazon SWF for this activity type. This timeout determines the total duration that the task can stay in open state. Set to -1 by default, which is a special value that indicates this timeout should be disabled. See the Amazon Simple Workflow Service API Reference for more details. @Asynchronous When used on a method in the workflow coordination logic, indicates that the method should be executed asynchronously. A call to the method will return immediately, but the actual execution will happen asynchronously when all Promise<> parameters passed to the methods become ready. Methods annotated with @Asynchronous must have a return type of Promise<> or void. @Asynchronous API Version 2021-04-28 176 AWS Flow Framework for Java daemon Developer Guide Indicates if the task created for the asynchronous method should be a daemon task. False by default. @Execute When used on a method
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Workflow Service API Reference for more details. @Asynchronous When used on a method in the workflow coordination logic, indicates that the method should be executed asynchronously. A call to the method will return immediately, but the actual execution will happen asynchronously when all Promise<> parameters passed to the methods become ready. Methods annotated with @Asynchronous must have a return type of Promise<> or void. @Asynchronous API Version 2021-04-28 176 AWS Flow Framework for Java daemon Developer Guide Indicates if the task created for the asynchronous method should be a daemon task. False by default. @Execute When used on a method in an interface annotated with the @Workflow annotation, identifies the entry point of the workflow. Important Only one method in the interface can be decorated with @Execute. The following parameters can be specified on this annotation: name Specifies the name of the workflow type. If not set, the name defaults to {prefix}{name}, where {prefix} is the name of the workflow interface followed by a '.' and {name} is the name of the @Execute-decorated method in the workflow. version Specifies the version of the workflow type. @ExponentialRetry When used on an activity or asynchronous method, sets an exponential retry policy if the method throws an unhandled exception. A retry attempt is made after a back-off period, which is calculated by the power of the number of attempts. The following parameters can be specified on this annotation: intialRetryIntervalSeconds Specifies the duration to wait before the first retry attempt. This value should not be greater than maximumRetryIntervalSeconds and retryExpirationSeconds. @Execute API Version 2021-04-28 177 AWS Flow Framework for Java Developer Guide maximumRetryIntervalSeconds Specifies the maximum duration between retry attempts. Once reached, the retry interval is capped to this value. Set to -1 by default, which means unlimited duration. retryExpirationSeconds Specifies the duration after which exponential retry will stop. Set to -1 by default, which means there is no expiration. backoffCoefficient Specifies the coefficient used to calculate the retry interval. See Exponential Retry Strategy. maximumAttempts Specifies the number of attempts after which exponential retry will stop. Set to -1 by default, which means there is no limit on the number of retry attempts. exceptionsToRetry Specifies the list of exception types that should trigger a retry. Unhandled exception of these types will not propagate further and the method will be retried after the calculated retry interval. By default, the list contains Throwable. excludeExceptions Specifies the list of exception types that should not trigger a retry. Unhandled exceptions of this type will be allowed to propagate. The list is empty by default. @GetState When used on a method in an interface annotated with the @Workflow annotation, identifies that the method is used to retrieve the latest workflow execution state. There can be at most one method with this annotation in an interface with the @Workflow annotation. Methods with this annotation must not take any parameters and must have a return type other than void. @ManualActivityCompletion This annotation can be used on an activity method to indicate that the activity task should not be completed when the method returns. The activity task will not be automatically completed and would need to be completed manually directly using the Amazon SWF API. This is useful for use @GetState API Version 2021-04-28 178 AWS Flow Framework for Java Developer Guide cases where the activity task is delegated to some external system that isn't automated or requires human intervention to be completed. @Signal When used on a method in an interface annotated with the @Workflow annotation, identifies a signal that can be received by executions of the workflow type declared by the interface. Use of this annotation is required to define a signal method. The following parameters can be specified on this annotation: name Specifies the name portion of the signal name. If not set, the name of the method is used. @SkipRegistration When used on an interface annotated with the @Workflow annotation, indicates that the workflow type should not be registered with Amazon SWF. One of @WorkflowRegistrationOptions and @SkipRegistrationOptions annotations must be used on an interface annotated with @Workflow, but not both. @Wait and @NoWait These annotations can be used on a parameter of type Promise<> to indicate whether the AWS Flow Framework for Java should wait for it to become ready before executing the method. By default, Promise<> parameters passed into @Asynchronous methods must become ready before method execution occurs. In certain scenarios, it is necessary to override this default behavior. Promise<> parameters passed into @Asynchronous methods and annotated with @NoWait are not waited for. Collections parameters (or subclasses of) that contain promises, such as List<Promise<Int>>, must be annotated with @Wait annotation. By default, the framework doesn't wait for the members of a collection. @Workflow This annotation is used on an interface to declare a workflow type. An interface
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AWS Flow Framework for Java should wait for it to become ready before executing the method. By default, Promise<> parameters passed into @Asynchronous methods must become ready before method execution occurs. In certain scenarios, it is necessary to override this default behavior. Promise<> parameters passed into @Asynchronous methods and annotated with @NoWait are not waited for. Collections parameters (or subclasses of) that contain promises, such as List<Promise<Int>>, must be annotated with @Wait annotation. By default, the framework doesn't wait for the members of a collection. @Workflow This annotation is used on an interface to declare a workflow type. An interface decorated with this annotation should contain exactly one method that is decorated with the @Execute annotation to declare an entry point for your workflow. @Signal API Version 2021-04-28 179 AWS Flow Framework for Java Developer Guide Note An interface can't have both @Workflow and @Activities annotations declared at once; they are mutually exclusive. The following parameters can be specified on this annotation: dataConverter Specifies which DataConverter to use when sending requests to, and receiving results from, workflow executions of this workflow type. The default is NullDataConverter which, in turn, falls back to JsonDataConverter to process all request and response data as JavaScript Object Notation (JSON). Example import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; import com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 3600) public interface GreeterWorkflow { @Execute(version = "1.0") public void greet(); } @WorkflowRegistrationOptions When used on an interface annotated with @Workflow, provides default settings used by Amazon SWF when registering the workflow type. Note Either @WorkflowRegistrationOptions or @SkipRegistrationOptions must be used on an interface annotated with @Workflow, but you can't specify both. @WorkflowRegistrationOptions API Version 2021-04-28 180 AWS Flow Framework for Java Developer Guide The following parameters can be specified on this annotation: Description An optional text description of the workflow type. defaultExecutionStartToCloseTimeoutSeconds Specifies the defaultExecutionStartToCloseTimeout registered with Amazon SWF for the workflow type. This is the total time that a workflow execution of this type can take to complete. For more information about workflow timeouts, see Amazon SWF Timeout Types . defaultTaskStartToCloseTimeoutSeconds Specifies the defaultTaskStartToCloseTimeout registered with Amazon SWF for the workflow type. This specifies the time a single decision task for a workflow execution of this type can take to complete. If you don't specify defaultTaskStartToCloseTimeout, it will default to 30 seconds. For more information about workflow timeouts, see Amazon SWF Timeout Types . defaultTaskList The default task list used for decision tasks for executions of this workflow type. The default set here can be overridden by using StartWorkflowOptions when starting a workflow execution. If you don't specify defaultTaskList, it will be set to USE_WORKER_TASK_LIST by default. This indicates that the task list used by the worker that is performing the workflow registration should be used. defaultChildPolicy Specifies the policy to use for child workflows if an execution of this type is terminated. The default value is ABANDON. The possible values are: • ABANDON – Allow the child workflow executions to keep running • TERMINATE – Terminate child workflow executions • REQUEST_CANCEL – Request cancellation of the child workflow executions @WorkflowRegistrationOptions API Version 2021-04-28 181 AWS Flow Framework for Java Developer Guide AWS Flow Framework for Java Exceptions The following exceptions are used by the AWS Flow Framework for Java. This section provides an overview of the exception. For more details, see the AWS SDK for Java documentation of the individual exceptions. Topics • ActivityFailureException • ActivityTaskException • ActivityTaskFailedException • ActivityTaskTimedOutException • ChildWorkflowException • ChildWorkflowFailedException • ChildWorkflowTerminatedException • ChildWorkflowTimedOutException • DataConverterException • DecisionException • ScheduleActivityTaskFailedException • SignalExternalWorkflowException • StartChildWorkflowFailedException • StartTimerFailedException • TimerException • WorkflowException ActivityFailureException This exception is used by the framework internally to communicate activity failure. When an activity fails due to an unhandled exception, it is wrapped in ActivityFailureException and reported to Amazon SWF. You need to deal with this exception only if you use the activity worker extensibility points. Your application code will never need to deal with this exception. Exceptions API Version 2021-04-28 182 AWS Flow Framework for Java ActivityTaskException Developer Guide This is the base class for activity task failure exceptions: ScheduleActivityTaskFailedException, ActivityTaskFailedException, ActivityTaskTimedoutException. It contains the task Id and activity type of the failed task. You can catch this exception in your workflow implementation to deal with activity failures in a generic way. ActivityTaskFailedException Unhandled exceptions in activities are reported back to the workflow implementation by throwing an ActivityTaskFailedException. The original exception can be retrieved from the cause property of this exception. The exception also provides other information that is useful for debugging purposes, such as the unique activity identifier in the history. The framework is able to provide the remote exception by serializing the original exception from the activity worker. ActivityTaskTimedOutException This exception is thrown if an activity was timed out by Amazon SWF. This could happen if the activity task could not be assigned
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with activity failures in a generic way. ActivityTaskFailedException Unhandled exceptions in activities are reported back to the workflow implementation by throwing an ActivityTaskFailedException. The original exception can be retrieved from the cause property of this exception. The exception also provides other information that is useful for debugging purposes, such as the unique activity identifier in the history. The framework is able to provide the remote exception by serializing the original exception from the activity worker. ActivityTaskTimedOutException This exception is thrown if an activity was timed out by Amazon SWF. This could happen if the activity task could not be assigned to the worker within the require time period or could not be completed by the worker in the required time. You can set these timeouts on the activity using the @ActivityRegistrationOptions annotation or using the ActivitySchedulingOptions parameter when calling the activity method. ChildWorkflowException Base class for exceptions used to report failure of child workflow execution. The exception contains the Ids of the child workflow execution as well as its workflow type. You can catch this exception to deal with child workflow execution failures in a generic way. ChildWorkflowFailedException Unhandled exceptions in child workflows are reported back to the parent workflow implementation by throwing a ChildWorkflowFailedException. The original exception can be retrieved from the cause property of this exception. The exception also provides other information that is useful for debugging purposes, such as the unique identifiers of the child execution. ActivityTaskException API Version 2021-04-28 183 AWS Flow Framework for Java Developer Guide ChildWorkflowTerminatedException This exception is thrown in parent workflow execution to report the termination of a child workflow execution. You should catch this exception if you want to deal with the termination of the child workflow, for example, to perform cleanup or compensation. ChildWorkflowTimedOutException This exception is thrown in parent workflow execution to report that a child workflow execution was timed out and closed by Amazon SWF. You should catch this exception if you want to deal with the forced closure of the child workflow, for example, to perform cleanup or compensation. DataConverterException The framework uses the DataConverter component to marshal and unmarshal data that is sent over the wire. This exception is thrown if the DataConverter fails to marshal or unmarshal data. This could happen for various reasons, for example, due to a mismatch in the DataConverter components being used to marshal and unmarshal the data. DecisionException This is the base class for exceptions that represent failures to enact a decision by Amazon SWF. You can catch this exception to generically deal with such exceptions. ScheduleActivityTaskFailedException This exception is thrown if Amazon SWF fails to schedule an activity task. This could happen due to various reasons—for example, the activity was deprecated, or an Amazon SWF limit on your account has been reached. The failureCause property in the exception specifies the exact cause of failure to schedule the activity. SignalExternalWorkflowException This exception is thrown if Amazon SWF fails to process a request by the workflow execution to signal another workflow execution. This happens if the target workflow execution could not be found—that is, the workflow execution you specified doesn't exist or is in closed state. ChildWorkflowTerminatedException API Version 2021-04-28 184 AWS Flow Framework for Java Developer Guide StartChildWorkflowFailedException This exception is thrown if Amazon SWF fails to start a child workflow execution. This could happen due to various reasons—for example, the type of child workflow specified was deprecated, or a Amazon SWF limit on your account has been reached. The failureCause property in the exception specifies the exact cause of failure to start the child workflow execution. StartTimerFailedException This exception is thrown if Amazon SWF fails to start a timer requested by the workflow execution. This could happen if the specified timer ID is already in use, or an Amazon SWF limit on your account has been reached. The failureCause property in the exception specifies the exact cause of failure. TimerException This is the base class for exceptions related to timers. WorkflowException This exception is used internally by the framework to report failures in workflow execution. You need to deal with this exception only if you are using a workflow worker extensibility point. AWS Flow Framework for Java Packages This section provides an overview of the packages included with the AWS Flow Framework for Java. For more information about each package, see the com.amazonaws.services.simpleworkflow.flow in the AWS SDK for Java API Reference. com.amazonaws.services.simpleworkflow.flow Contains components that integrate with Amazon SWF. com.amazonaws.services.simpleworkflow.flow.annotations Contains the annotations used by the AWS Flow Framework for Java programming model. com.amazonaws.services.simpleworkflow.flow.aspectj Contains AWS Flow Framework for Java components required for features such as @Asynchronous and @ExponentialRetry. StartChildWorkflowFailedException API Version 2021-04-28 185 AWS Flow Framework for Java Developer Guide com.amazonaws.services.simpleworkflow.flow.common Contains common utilities such as framework-defined constants. com.amazonaws.services.simpleworkflow.flow.core Contains core features such as Task and Promise. com.amazonaws.services.simpleworkflow.flow.generic
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section provides an overview of the packages included with the AWS Flow Framework for Java. For more information about each package, see the com.amazonaws.services.simpleworkflow.flow in the AWS SDK for Java API Reference. com.amazonaws.services.simpleworkflow.flow Contains components that integrate with Amazon SWF. com.amazonaws.services.simpleworkflow.flow.annotations Contains the annotations used by the AWS Flow Framework for Java programming model. com.amazonaws.services.simpleworkflow.flow.aspectj Contains AWS Flow Framework for Java components required for features such as @Asynchronous and @ExponentialRetry. StartChildWorkflowFailedException API Version 2021-04-28 185 AWS Flow Framework for Java Developer Guide com.amazonaws.services.simpleworkflow.flow.common Contains common utilities such as framework-defined constants. com.amazonaws.services.simpleworkflow.flow.core Contains core features such as Task and Promise. com.amazonaws.services.simpleworkflow.flow.generic Contains core components, such as generic clients, that other features build on. com.amazonaws.services.simpleworkflow.flow.interceptors Contains implementations of framework provided decorators including RetryDecorator. com.amazonaws.services.simpleworkflow.flow.junit Contains components that provide Junit integration. com.amazonaws.services.simpleworkflow.flow.pojo Contains classes that implement activity and workflow definitions for the annotation-based programming model. com.amazonaws.services.simpleworkflow.flow.spring Contains components that provide Spring integration. com.amazonaws.services.simpleworkflow.flow.test Contains helper classes, such as TestWorkflowClock, for unit testing workflow implementations. com.amazonaws.services.simpleworkflow.flow.worker Contains implementations of activity and workflow workers. Packages API Version 2021-04-28 186 AWS Flow Framework for Java Developer Guide Document History The following table describes the important changes to the documentation since the last release of the AWS Flow Framework for Java Developer Guide. • API version: 2012-01-25 • Latest documentation update: June 25, 2018 Change Description Date Changed Update Fixed an error in the backoffCoefficient on for @ExponentialRetry . See @ExponentialRetry. descripti June 25, 2018 Update Cleaned up the code examples throughout this guide. June 5, 2017 Update Update Update New feature New feature Simplified and improved the organization and contents of this guide. May 19, 2017 Simplified and improved the Making Changes to Decider Code: Versioning and Feature Flags section. April 10, 2017 Added the new Best Practices section with new guidance on making changes to decider code. March 3, 2017 You can specify Lambda tasks in addition to traditional Activity tasks in your workflows. For more information, see Implementing AWS Lambda Tasks. July 21, 2015 Amazon SWF includes support for setting the task priority on a task list, attempting to deliver the tasks with a higher priority before tasks with lower priority. For more information, see Setting task priority in Amazon SWF. December 17, 2014 Update Made updates and fixes. August 1, 2013 API Version 2021-04-28 187 AWS Flow Framework for Java Change Description Developer Guide Date Changed Update • Made updates and fixes, including updates of the setup instructions for Eclipse 4.3 and AWS SDK for Java 1.4.7. June 28, 2013 • Added a new set of tutorials for building starter scenarios New feature The initial release of the AWS Flow Framework for Java. February 27, 2012 API Version 2021-04-28 188
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API Reference Amazon Simple Workflow Service API Version 2012-01-25 Copyright © 2025 Amazon Web Services, Inc. and/or its affiliates. All rights reserved. Amazon Simple Workflow Service API Reference Amazon Simple Workflow Service: API Reference Copyright © 2025 Amazon Web Services, Inc. and/or its affiliates. All rights reserved. Amazon's trademarks and trade dress may not be used in connection with any product or service that is not Amazon's, in any manner that is likely to cause confusion among customers, or in any manner that disparages or discredits Amazon. All other trademarks not owned by Amazon are the property of their respective owners, who may or may not be affiliated with, connected to, or sponsored by Amazon. Amazon Simple Workflow Service Table of Contents API Reference Welcome ........................................................................................................................................... 1 Actions .............................................................................................................................................. 2 CountClosedWorkflowExecutions .............................................................................................................. 4 Request Syntax ........................................................................................................................................ 4 Request Parameters ................................................................................................................................ 5 Response Syntax ...................................................................................................................................... 7 Response Elements ................................................................................................................................. 7 Errors .......................................................................................................................................................... 8 Examples ................................................................................................................................................... 8 See Also .................................................................................................................................................. 10 CountOpenWorkflowExecutions .............................................................................................................. 11 Request Syntax ...................................................................................................................................... 11 Request Parameters .............................................................................................................................. 12 Response Syntax ................................................................................................................................... 13 Response Elements ............................................................................................................................... 13 Errors ....................................................................................................................................................... 14 Examples ................................................................................................................................................. 14 See Also .................................................................................................................................................. 15 CountPendingActivityTasks ...................................................................................................................... 17 Request Syntax ...................................................................................................................................... 17 Request Parameters .............................................................................................................................. 17 Response Syntax ................................................................................................................................... 18 Response Elements ............................................................................................................................... 18 Errors ....................................................................................................................................................... 19 Examples ................................................................................................................................................. 19 See Also .................................................................................................................................................. 20 CountPendingDecisionTasks ..................................................................................................................... 21 Request Syntax ...................................................................................................................................... 21 Request Parameters .............................................................................................................................. 21 Response Syntax ................................................................................................................................... 22 Response Elements ............................................................................................................................... 22 Errors ....................................................................................................................................................... 23 Examples ................................................................................................................................................. 23 See Also .................................................................................................................................................. 24 API Version 2012-01-25 iii Amazon Simple Workflow Service API Reference DeleteActivityType ..................................................................................................................................... 25 Request Syntax ...................................................................................................................................... 25 Request Parameters .............................................................................................................................. 25 Response Elements ............................................................................................................................... 26 Errors ....................................................................................................................................................... 26 See Also .................................................................................................................................................. 27 DeleteWorkflowType .................................................................................................................................. 28 Request Syntax ...................................................................................................................................... 28 Request Parameters .............................................................................................................................. 28 Response Elements ............................................................................................................................... 29 Errors ....................................................................................................................................................... 29 See Also .................................................................................................................................................. 30 DeprecateActivityType ............................................................................................................................... 31 Request Syntax ...................................................................................................................................... 31 Request Parameters .............................................................................................................................. 31 Response Elements ............................................................................................................................... 32 Errors ....................................................................................................................................................... 32 Examples ................................................................................................................................................. 33 See Also .................................................................................................................................................. 34 DeprecateDomain ....................................................................................................................................... 35 Request Syntax ...................................................................................................................................... 35 Request Parameters .............................................................................................................................. 35 Response Elements ............................................................................................................................... 36 Errors ....................................................................................................................................................... 36 Examples ................................................................................................................................................. 36 See Also .................................................................................................................................................. 37 DeprecateWorkflowType ........................................................................................................................... 39 Request Syntax ...................................................................................................................................... 39 Request Parameters .............................................................................................................................. 40 Response Elements ............................................................................................................................... 40 Errors ....................................................................................................................................................... 40 Examples ................................................................................................................................................. 41 See Also .................................................................................................................................................. 42 DescribeActivityType .................................................................................................................................. 43 Request Syntax ...................................................................................................................................... 43 Request Parameters .............................................................................................................................. 43 API Version 2012-01-25 iv Amazon Simple Workflow Service API Reference Response Syntax ................................................................................................................................... 44 Response Elements ............................................................................................................................... 45 Errors ....................................................................................................................................................... 45 Examples ................................................................................................................................................. 46 See Also .................................................................................................................................................. 47 DescribeDomain .......................................................................................................................................... 48 Request Syntax ...................................................................................................................................... 48 Request Parameters .............................................................................................................................. 48 Response Syntax ................................................................................................................................... 49 Response Elements ............................................................................................................................... 49 Errors ....................................................................................................................................................... 49 Examples ................................................................................................................................................. 50 See Also .................................................................................................................................................. 51 DescribeWorkflowExecution ..................................................................................................................... 52 Request Syntax ...................................................................................................................................... 52 Request Parameters .............................................................................................................................. 52 Response Syntax ................................................................................................................................... 53 Response Elements ............................................................................................................................... 54 Errors ....................................................................................................................................................... 55 Examples ................................................................................................................................................. 55 See Also .................................................................................................................................................. 57 DescribeWorkflowType .............................................................................................................................. 59 Request Syntax ...................................................................................................................................... 59 Request Parameters .............................................................................................................................. 59 Response Syntax ................................................................................................................................... 60 Response Elements ............................................................................................................................... 61 Errors ....................................................................................................................................................... 61 Examples ................................................................................................................................................. 62 See Also .................................................................................................................................................. 63 GetWorkflowExecutionHistory ................................................................................................................. 65 Request Syntax ...................................................................................................................................... 65 Request Parameters .............................................................................................................................. 66 Response Syntax ................................................................................................................................... 67 Response Elements ............................................................................................................................... 76 Errors ....................................................................................................................................................... 77 Examples ................................................................................................................................................. 78 API Version 2012-01-25 v Amazon Simple Workflow Service API Reference See Also .................................................................................................................................................. 82 ListActivityTypes ......................................................................................................................................... 83 Request Syntax ...................................................................................................................................... 83 Request Parameters .............................................................................................................................. 83 Response Syntax ................................................................................................................................... 85 Response Elements ............................................................................................................................... 85 Errors ....................................................................................................................................................... 86 Examples ................................................................................................................................................. 86 See Also .................................................................................................................................................. 87 ListClosedWorkflowExecutions ................................................................................................................ 89 Request Syntax ...................................................................................................................................... 89 Request Parameters .............................................................................................................................. 90 Response Syntax ................................................................................................................................... 93 Response Elements ............................................................................................................................... 94 Errors ....................................................................................................................................................... 95 Examples ................................................................................................................................................. 95 See Also .................................................................................................................................................. 97 ListDomains ................................................................................................................................................. 99 Request Syntax ...................................................................................................................................... 99 Request Parameters ........................................................................................................................... 100 Response Syntax ................................................................................................................................. 101 Response Elements ............................................................................................................................ 101 Errors ..................................................................................................................................................... 102 Examples ............................................................................................................................................... 102 See Also ................................................................................................................................................ 103 ListOpenWorkflowExecutions ................................................................................................................ 105 Request Syntax .................................................................................................................................... 105 Request Parameters ........................................................................................................................... 106 Response Syntax ................................................................................................................................. 108 Response Elements ............................................................................................................................ 109 Errors ..................................................................................................................................................... 109 Examples ............................................................................................................................................... 110 See Also ................................................................................................................................................ 111 ListTagsForResource ................................................................................................................................ 113 Request Syntax .................................................................................................................................... 113 Request Parameters ........................................................................................................................... 113 API Version 2012-01-25 vi Amazon Simple Workflow Service API Reference Response Syntax ................................................................................................................................. 113 Response Elements ............................................................................................................................ 113 Errors ..................................................................................................................................................... 114 See Also ................................................................................................................................................ 114 ListWorkflowTypes ................................................................................................................................... 116 Request Syntax .................................................................................................................................... 116 Request Parameters ........................................................................................................................... 116 Response Syntax ................................................................................................................................. 118 Response Elements ............................................................................................................................ 118 Errors ..................................................................................................................................................... 119 Examples ............................................................................................................................................... 119 See Also ................................................................................................................................................ 121 PollForActivityTask ................................................................................................................................... 122 Request Syntax .................................................................................................................................... 122 Request Parameters ........................................................................................................................... 123 Response Syntax ................................................................................................................................. 124 Response Elements ............................................................................................................................ 124 Errors ..................................................................................................................................................... 125 Examples ............................................................................................................................................... 126 See Also ................................................................................................................................................ 127 PollForDecisionTask ................................................................................................................................. 129 Request Syntax .................................................................................................................................... 130 Request Parameters ........................................................................................................................... 130 Response Syntax ................................................................................................................................. 132 Response Elements ............................................................................................................................ 142 Errors ..................................................................................................................................................... 143 Examples ............................................................................................................................................... 144 See Also ................................................................................................................................................ 147 RecordActivityTaskHeartbeat ................................................................................................................. 148 Request Syntax .................................................................................................................................... 149 Request Parameters ........................................................................................................................... 149 Response Syntax ................................................................................................................................. 150 Response Elements ............................................................................................................................ 150 Errors .....................................................................................................................................................
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Parameters ........................................................................................................................... 116 Response Syntax ................................................................................................................................. 118 Response Elements ............................................................................................................................ 118 Errors ..................................................................................................................................................... 119 Examples ............................................................................................................................................... 119 See Also ................................................................................................................................................ 121 PollForActivityTask ................................................................................................................................... 122 Request Syntax .................................................................................................................................... 122 Request Parameters ........................................................................................................................... 123 Response Syntax ................................................................................................................................. 124 Response Elements ............................................................................................................................ 124 Errors ..................................................................................................................................................... 125 Examples ............................................................................................................................................... 126 See Also ................................................................................................................................................ 127 PollForDecisionTask ................................................................................................................................. 129 Request Syntax .................................................................................................................................... 130 Request Parameters ........................................................................................................................... 130 Response Syntax ................................................................................................................................. 132 Response Elements ............................................................................................................................ 142 Errors ..................................................................................................................................................... 143 Examples ............................................................................................................................................... 144 See Also ................................................................................................................................................ 147 RecordActivityTaskHeartbeat ................................................................................................................. 148 Request Syntax .................................................................................................................................... 149 Request Parameters ........................................................................................................................... 149 Response Syntax ................................................................................................................................. 150 Response Elements ............................................................................................................................ 150 Errors ..................................................................................................................................................... 150 Examples ............................................................................................................................................... 151 See Also ................................................................................................................................................ 152 API Version 2012-01-25 vii Amazon Simple Workflow Service API Reference RegisterActivityType ................................................................................................................................ 153 Request Syntax .................................................................................................................................... 153 Request Parameters ........................................................................................................................... 154 Response Elements ............................................................................................................................ 157 Errors ..................................................................................................................................................... 157 Examples ............................................................................................................................................... 158 See Also ................................................................................................................................................ 159 RegisterDomain ........................................................................................................................................ 161 Request Syntax .................................................................................................................................... 161 Request Parameters ........................................................................................................................... 161 Response Elements ............................................................................................................................ 163 Errors ..................................................................................................................................................... 163 Examples ............................................................................................................................................... 164 See Also ................................................................................................................................................ 165 RegisterWorkflowType ............................................................................................................................ 166 Request Syntax .................................................................................................................................... 166 Request Parameters ........................................................................................................................... 167 Response Elements ............................................................................................................................ 170 Errors ..................................................................................................................................................... 170 Examples ............................................................................................................................................... 171 See Also ................................................................................................................................................ 172 RequestCancelWorkflowExecution ........................................................................................................ 174 Request Syntax .................................................................................................................................... 174 Request Parameters ........................................................................................................................... 175 Response Elements ............................................................................................................................ 175 Errors ..................................................................................................................................................... 176 Examples ............................................................................................................................................... 176 See Also ................................................................................................................................................ 177 RespondActivityTaskCanceled ............................................................................................................... 178 Request Syntax .................................................................................................................................... 178 Request Parameters ........................................................................................................................... 179 Response Elements ............................................................................................................................ 179 Errors ..................................................................................................................................................... 179 Examples ............................................................................................................................................... 180 See Also ................................................................................................................................................ 181 RespondActivityTaskCompleted ............................................................................................................ 182 API Version 2012-01-25 viii Amazon Simple Workflow Service API Reference Request Syntax .................................................................................................................................... 182 Request Parameters ........................................................................................................................... 183 Response Elements ............................................................................................................................ 183 Errors ..................................................................................................................................................... 183 Examples ............................................................................................................................................... 184 See Also ................................................................................................................................................ 185 RespondActivityTaskFailed ..................................................................................................................... 186 Request Syntax .................................................................................................................................... 186 Request Parameters ........................................................................................................................... 186 Response Elements ............................................................................................................................ 187 Errors ..................................................................................................................................................... 187 Examples ............................................................................................................................................... 188 See Also ................................................................................................................................................ 189 RespondDecisionTaskCompleted .......................................................................................................... 190 Request Syntax .................................................................................................................................... 190 Request Parameters ........................................................................................................................... 192 Response Elements ............................................................................................................................ 194 Errors ..................................................................................................................................................... 194 Examples ............................................................................................................................................... 195 See Also ................................................................................................................................................ 196 SignalWorkflowExecution ....................................................................................................................... 198 Request Syntax .................................................................................................................................... 198 Request Parameters ........................................................................................................................... 199 Response Elements ............................................................................................................................ 200 Errors ..................................................................................................................................................... 200 Examples ............................................................................................................................................... 200 See Also ................................................................................................................................................ 201 StartWorkflowExecution ......................................................................................................................... 203 Request Syntax .................................................................................................................................... 203 Request Parameters ........................................................................................................................... 204 Response Syntax ................................................................................................................................. 208 Response Elements ............................................................................................................................ 208 Errors ..................................................................................................................................................... 209 Examples ............................................................................................................................................... 210 See Also ................................................................................................................................................ 212 TagResource .............................................................................................................................................. 213 API Version 2012-01-25 ix Amazon Simple Workflow Service API Reference Request Syntax .................................................................................................................................... 213 Request Parameters ........................................................................................................................... 213 Response Elements ............................................................................................................................ 214 Errors ..................................................................................................................................................... 214 See Also ................................................................................................................................................ 214 TerminateWorkflowExecution ................................................................................................................ 216 Request Syntax .................................................................................................................................... 217 Request Parameters ........................................................................................................................... 217 Response Elements ............................................................................................................................ 219 Errors ..................................................................................................................................................... 219 Examples ............................................................................................................................................... 219 See Also ................................................................................................................................................ 220 UndeprecateActivityType ........................................................................................................................ 222 Request Syntax .................................................................................................................................... 222 Request Parameters ........................................................................................................................... 223 Response Elements ............................................................................................................................ 223 Errors ..................................................................................................................................................... 223 See Also ................................................................................................................................................ 224 UndeprecateDomain ................................................................................................................................ 225 Request Syntax .................................................................................................................................... 225 Request Parameters ........................................................................................................................... 225 Response Elements ............................................................................................................................ 226 Errors ..................................................................................................................................................... 226 See Also ................................................................................................................................................ 226 UndeprecateWorkflowType .................................................................................................................... 228 Request Syntax .................................................................................................................................... 228 Request Parameters ........................................................................................................................... 229 Response Elements ............................................................................................................................ 229 Errors ..................................................................................................................................................... 229 See Also ................................................................................................................................................ 230 UntagResource .......................................................................................................................................... 231 Request Syntax .................................................................................................................................... 231 Request Parameters ........................................................................................................................... 231 Response Elements ............................................................................................................................ 231 Errors ..................................................................................................................................................... 232 See Also ................................................................................................................................................ 232 API Version 2012-01-25 x Amazon Simple Workflow Service API Reference Data Types ................................................................................................................................... 234 ActivityTask ............................................................................................................................................... 238 Contents ............................................................................................................................................... 238 See Also ................................................................................................................................................ 239 ActivityTaskCanceledEventAttributes ................................................................................................... 240 Contents ............................................................................................................................................... 240 See Also ................................................................................................................................................ 241 ActivityTaskCancelRequestedEventAttributes .................................................................................... 242 Contents ............................................................................................................................................... 242 See Also ................................................................................................................................................ 242 ActivityTaskCompletedEventAttributes ............................................................................................... 243 Contents ............................................................................................................................................... 243 See Also ................................................................................................................................................ 243 ActivityTaskFailedEventAttributes ........................................................................................................ 245 Contents ............................................................................................................................................... 245 See Also ................................................................................................................................................ 246 ActivityTaskScheduledEventAttributes ................................................................................................ 247 Contents ............................................................................................................................................... 247 See Also ................................................................................................................................................ 249 ActivityTaskStartedEventAttributes ..................................................................................................... 250 Contents ............................................................................................................................................... 250 See Also ................................................................................................................................................ 250 ActivityTaskTimedOutEventAttributes ................................................................................................. 251 Contents ............................................................................................................................................... 251 See Also ................................................................................................................................................ 252 ActivityType ............................................................................................................................................... 253 Contents ............................................................................................................................................... 253 See Also ................................................................................................................................................ 253 ActivityTypeConfiguration ...................................................................................................................... 255 Contents ............................................................................................................................................... 255 See Also ................................................................................................................................................ 257 ActivityTypeInfo ........................................................................................................................................ 258 Contents ............................................................................................................................................... 258 See Also ................................................................................................................................................ 259 CancelTimerDecisionAttributes ............................................................................................................. 260 Contents ............................................................................................................................................... 260 API Version 2012-01-25 xi Amazon Simple Workflow Service API Reference See Also ................................................................................................................................................ 260 CancelTimerFailedEventAttributes ....................................................................................................... 261 Contents ............................................................................................................................................... 261 See Also ................................................................................................................................................ 262 CancelWorkflowExecutionDecisionAttributes ..................................................................................... 263 Contents ............................................................................................................................................... 263 See Also ................................................................................................................................................ 263 CancelWorkflowExecutionFailedEventAttributes ............................................................................... 264 Contents ............................................................................................................................................... 264 See Also ................................................................................................................................................ 264 ChildWorkflowExecutionCanceledEventAttributes ............................................................................ 266 Contents ............................................................................................................................................... 266 See Also ................................................................................................................................................ 267 ChildWorkflowExecutionCompletedEventAttributes ........................................................................ 268 Contents ............................................................................................................................................... 268 See Also ................................................................................................................................................ 269 ChildWorkflowExecutionFailedEventAttributes ................................................................................. 270 Contents ............................................................................................................................................... 270 See Also ................................................................................................................................................ 271 ChildWorkflowExecutionStartedEventAttributes ............................................................................... 272 Contents ............................................................................................................................................... 272 See Also ................................................................................................................................................ 272 ChildWorkflowExecutionTerminatedEventAttributes ....................................................................... 274 Contents ............................................................................................................................................... 274 See Also ................................................................................................................................................ 275 ChildWorkflowExecutionTimedOutEventAttributes .......................................................................... 276 Contents ............................................................................................................................................... 276 See Also ................................................................................................................................................ 277 CloseStatusFilter ....................................................................................................................................... 278 Contents ............................................................................................................................................... 278 See Also ................................................................................................................................................ 278 CompleteWorkflowExecutionDecisionAttributes ............................................................................... 279 Contents ............................................................................................................................................... 279 See Also ................................................................................................................................................ 279 CompleteWorkflowExecutionFailedEventAttributes ......................................................................... 280 Contents ............................................................................................................................................... 280 API Version 2012-01-25 xii Amazon Simple Workflow Service API Reference See Also 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264 ChildWorkflowExecutionCanceledEventAttributes ............................................................................ 266 Contents ............................................................................................................................................... 266 See Also ................................................................................................................................................ 267 ChildWorkflowExecutionCompletedEventAttributes ........................................................................ 268 Contents ............................................................................................................................................... 268 See Also ................................................................................................................................................ 269 ChildWorkflowExecutionFailedEventAttributes ................................................................................. 270 Contents ............................................................................................................................................... 270 See Also ................................................................................................................................................ 271 ChildWorkflowExecutionStartedEventAttributes ............................................................................... 272 Contents ............................................................................................................................................... 272 See Also ................................................................................................................................................ 272 ChildWorkflowExecutionTerminatedEventAttributes ....................................................................... 274 Contents ............................................................................................................................................... 274 See Also ................................................................................................................................................ 275 ChildWorkflowExecutionTimedOutEventAttributes .......................................................................... 276 Contents ............................................................................................................................................... 276 See Also ................................................................................................................................................ 277 CloseStatusFilter ....................................................................................................................................... 278 Contents ............................................................................................................................................... 278 See Also ................................................................................................................................................ 278 CompleteWorkflowExecutionDecisionAttributes ............................................................................... 279 Contents ............................................................................................................................................... 279 See Also ................................................................................................................................................ 279 CompleteWorkflowExecutionFailedEventAttributes ......................................................................... 280 Contents ............................................................................................................................................... 280 API Version 2012-01-25 xii Amazon Simple Workflow Service API Reference See Also ................................................................................................................................................ 280 ContinueAsNewWorkflowExecutionDecisionAttributes .................................................................... 282 Contents ............................................................................................................................................... 282 See Also ................................................................................................................................................ 285 ContinueAsNewWorkflowExecutionFailedEventAttributes .............................................................. 287 Contents ............................................................................................................................................... 287 See Also ................................................................................................................................................ 288 Decision ...................................................................................................................................................... 289 Contents ............................................................................................................................................... 292 See Also ................................................................................................................................................ 295 DecisionTask .............................................................................................................................................. 296 Contents ............................................................................................................................................... 296 See Also ................................................................................................................................................ 297 DecisionTaskCompletedEventAttributes .............................................................................................. 298 Contents ............................................................................................................................................... 298 See Also ................................................................................................................................................ 299 DecisionTaskScheduledEventAttributes ............................................................................................... 300 Contents ............................................................................................................................................... 300 See Also ................................................................................................................................................ 301 DecisionTaskStartedEventAttributes .................................................................................................... 302 Contents ............................................................................................................................................... 302 See Also ................................................................................................................................................ 302 DecisionTaskTimedOutEventAttributes ............................................................................................... 303 Contents ............................................................................................................................................... 303 See Also ................................................................................................................................................ 303 DomainConfiguration .............................................................................................................................. 305 Contents ............................................................................................................................................... 305 See Also ................................................................................................................................................ 305 DomainInfo ................................................................................................................................................ 306 Contents ............................................................................................................................................... 306 See Also ................................................................................................................................................ 307 ExecutionTimeFilter ................................................................................................................................. 308 Contents ............................................................................................................................................... 308 See Also ................................................................................................................................................ 308 ExternalWorkflowExecutionCancelRequestedEventAttributes ........................................................ 309 Contents ............................................................................................................................................... 309 API Version 2012-01-25 xiii Amazon Simple Workflow Service API Reference See Also ................................................................................................................................................ 309 ExternalWorkflowExecutionSignaledEventAttributes ....................................................................... 310 Contents ............................................................................................................................................... 310 See Also ................................................................................................................................................ 310 FailWorkflowExecutionDecisionAttributes .......................................................................................... 311 Contents ............................................................................................................................................... 311 See Also ................................................................................................................................................ 312 FailWorkflowExecutionFailedEventAttributes ..................................................................................... 313 Contents ............................................................................................................................................... 313 See Also ................................................................................................................................................ 313 HistoryEvent .............................................................................................................................................. 315 Contents ............................................................................................................................................... 317 See Also ................................................................................................................................................ 329 LambdaFunctionCompletedEventAttributes ...................................................................................... 330 Contents ............................................................................................................................................... 330 See Also ................................................................................................................................................ 330 LambdaFunctionFailedEventAttributes ............................................................................................... 332 Contents ............................................................................................................................................... 332 See Also ................................................................................................................................................ 333 LambdaFunctionScheduledEventAttributes ....................................................................................... 334 Contents ............................................................................................................................................... 334 See Also ................................................................................................................................................ 335 LambdaFunctionStartedEventAttributes ............................................................................................. 336 Contents ............................................................................................................................................... 336 See Also ................................................................................................................................................ 336 LambdaFunctionTimedOutEventAttributes ........................................................................................ 337 Contents ............................................................................................................................................... 337 See Also ................................................................................................................................................ 337 MarkerRecordedEventAttributes ........................................................................................................... 339 Contents ............................................................................................................................................... 339 See Also ................................................................................................................................................ 339 RecordMarkerDecisionAttributes ........................................................................................................... 341 Contents ............................................................................................................................................... 341 See Also ................................................................................................................................................ 342 RecordMarkerFailedEventAttributes ..................................................................................................... 343 Contents ............................................................................................................................................... 343 API Version 2012-01-25 xiv Amazon Simple Workflow Service API Reference See Also ................................................................................................................................................ 344 RequestCancelActivityTaskDecisionAttributes .................................................................................... 345 Contents ............................................................................................................................................... 345 See Also ................................................................................................................................................ 345 RequestCancelActivityTaskFailedEventAttributes .............................................................................. 346 Contents ............................................................................................................................................... 346 See Also ................................................................................................................................................ 347 RequestCancelExternalWorkflowExecutionDecisionAttributes ....................................................... 348 Contents ............................................................................................................................................... 348 See Also ................................................................................................................................................ 349 RequestCancelExternalWorkflowExecutionFailedEventAttributes ................................................. 350 Contents ............................................................................................................................................... 350 See Also ................................................................................................................................................ 351 RequestCancelExternalWorkflowExecutionInitiatedEventAttributes ............................................. 353 Contents ............................................................................................................................................... 353 See Also ................................................................................................................................................ 354 ResourceTag .............................................................................................................................................. 355 Contents ............................................................................................................................................... 355 See Also ................................................................................................................................................ 355 ScheduleActivityTaskDecisionAttributes .............................................................................................. 356 Contents ............................................................................................................................................... 356 See Also ................................................................................................................................................ 360 ScheduleActivityTaskFailedEventAttributes ........................................................................................ 361 Contents ............................................................................................................................................... 361 See Also ................................................................................................................................................ 362 ScheduleLambdaFunctionDecisionAttributes ..................................................................................... 363 Contents ............................................................................................................................................... 363 See Also ................................................................................................................................................ 364 ScheduleLambdaFunctionFailedEventAttributes ............................................................................... 365 Contents ............................................................................................................................................... 365 See Also ................................................................................................................................................ 366 SignalExternalWorkflowExecutionDecisionAttributes ...................................................................... 367 Contents ............................................................................................................................................... 367 See Also ................................................................................................................................................ 368 SignalExternalWorkflowExecutionFailedEventAttributes ................................................................. 369 Contents ............................................................................................................................................... 369 API Version 2012-01-25 xv Amazon Simple Workflow Service API Reference See Also ................................................................................................................................................ 370 SignalExternalWorkflowExecutionInitiatedEventAttributes ............................................................ 372 Contents ............................................................................................................................................... 372 See Also ................................................................................................................................................ 373 StartChildWorkflowExecutionDecisionAttributes .............................................................................. 374 Contents ............................................................................................................................................... 374 See Also ................................................................................................................................................ 378 StartChildWorkflowExecutionFailedEventAttributes ........................................................................ 379 Contents ............................................................................................................................................... 379 See Also ................................................................................................................................................ 381 StartChildWorkflowExecutionInitiatedEventAttributes .................................................................... 382 Contents ............................................................................................................................................... 382 See Also ................................................................................................................................................ 385 StartLambdaFunctionFailedEventAttributes ...................................................................................... 386 Contents ............................................................................................................................................... 386 See Also ................................................................................................................................................ 387 StartTimerDecisionAttributes ................................................................................................................ 388 Contents ............................................................................................................................................... 388 See Also ................................................................................................................................................ 389 StartTimerFailedEventAttributes .......................................................................................................... 390 Contents ............................................................................................................................................... 390 See Also ................................................................................................................................................ 391 TagFilter ..................................................................................................................................................... 392 Contents ............................................................................................................................................... 392 See Also ................................................................................................................................................ 392 TaskList ....................................................................................................................................................... 393 Contents ............................................................................................................................................... 393 See Also ................................................................................................................................................ 393 TimerCanceledEventAttributes .............................................................................................................. 394 Contents ............................................................................................................................................... 394 See Also ................................................................................................................................................ 394 TimerFiredEventAttributes ..................................................................................................................... 396 Contents ............................................................................................................................................... 396 See Also ................................................................................................................................................ 396 TimerStartedEventAttributes ................................................................................................................. 397 Contents ............................................................................................................................................... 397 API Version 2012-01-25 xvi Amazon Simple Workflow Service API Reference See Also ................................................................................................................................................ 398 WorkflowExecution .................................................................................................................................. 399 Contents ............................................................................................................................................... 399 See Also ................................................................................................................................................ 399 WorkflowExecutionCanceledEventAttributes ..................................................................................... 400 Contents ............................................................................................................................................... 400 See Also ................................................................................................................................................ 400 WorkflowExecutionCancelRequestedEventAttributes ....................................................................... 401 Contents ............................................................................................................................................... 401 See Also ................................................................................................................................................ 401 WorkflowExecutionCompletedEventAttributes .................................................................................. 403 Contents ............................................................................................................................................... 403 See Also ................................................................................................................................................ 403 WorkflowExecutionConfiguration ......................................................................................................... 404 Contents ............................................................................................................................................... 404 See Also ................................................................................................................................................ 405 WorkflowExecutionContinuedAsNewEventAttributes ...................................................................... 407 Contents ............................................................................................................................................... 407 See Also ................................................................................................................................................ 409 WorkflowExecutionFailedEventAttributes ........................................................................................... 411 Contents ............................................................................................................................................... 411 See Also ................................................................................................................................................ 411 WorkflowExecutionFilter ......................................................................................................................... 413 Contents ............................................................................................................................................... 413 See Also ................................................................................................................................................ 413 WorkflowExecutionInfo ........................................................................................................................... 414 Contents ............................................................................................................................................... 414 See Also ................................................................................................................................................ 416 WorkflowExecutionOpenCounts ........................................................................................................... 417 Contents ............................................................................................................................................... 417 See Also ................................................................................................................................................ 418 WorkflowExecutionSignaledEventAttributes ...................................................................................... 419 Contents ............................................................................................................................................... 419 See Also ................................................................................................................................................ 420 WorkflowExecutionStartedEventAttributes ........................................................................................ 421 Contents ............................................................................................................................................... 421 API Version 2012-01-25 xvii Amazon Simple Workflow Service API Reference See Also ................................................................................................................................................ 424 WorkflowExecutionTerminatedEventAttributes ................................................................................. 425 Contents ............................................................................................................................................... 425 See Also ................................................................................................................................................ 426 WorkflowExecutionTimedOutEventAttributes ................................................................................... 427 Contents ............................................................................................................................................... 427 See Also ................................................................................................................................................ 427 WorkflowType ........................................................................................................................................... 429 Contents ............................................................................................................................................... 429 See Also ................................................................................................................................................ 429 WorkflowTypeConfiguration .................................................................................................................. 431 Contents ............................................................................................................................................... 431 See Also ................................................................................................................................................ 433 WorkflowTypeFilter .................................................................................................................................. 434 Contents ............................................................................................................................................... 434 See Also ................................................................................................................................................
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413 WorkflowExecutionInfo ........................................................................................................................... 414 Contents ............................................................................................................................................... 414 See Also ................................................................................................................................................ 416 WorkflowExecutionOpenCounts ........................................................................................................... 417 Contents ............................................................................................................................................... 417 See Also ................................................................................................................................................ 418 WorkflowExecutionSignaledEventAttributes ...................................................................................... 419 Contents ............................................................................................................................................... 419 See Also ................................................................................................................................................ 420 WorkflowExecutionStartedEventAttributes ........................................................................................ 421 Contents ............................................................................................................................................... 421 API Version 2012-01-25 xvii Amazon Simple Workflow Service API Reference See Also ................................................................................................................................................ 424 WorkflowExecutionTerminatedEventAttributes ................................................................................. 425 Contents ............................................................................................................................................... 425 See Also ................................................................................................................................................ 426 WorkflowExecutionTimedOutEventAttributes ................................................................................... 427 Contents ............................................................................................................................................... 427 See Also ................................................................................................................................................ 427 WorkflowType ........................................................................................................................................... 429 Contents ............................................................................................................................................... 429 See Also ................................................................................................................................................ 429 WorkflowTypeConfiguration .................................................................................................................. 431 Contents ............................................................................................................................................... 431 See Also ................................................................................................................................................ 433 WorkflowTypeFilter .................................................................................................................................. 434 Contents ............................................................................................................................................... 434 See Also ................................................................................................................................................ 434 WorkflowTypeInfo .................................................................................................................................... 435 Contents ............................................................................................................................................... 435 See Also ................................................................................................................................................ 436 Common Parameters ................................................................................................................... 437 Common Errors ............................................................................................................................ 440 API Version 2012-01-25 xviii Amazon Simple Workflow Service API Reference Welcome The Amazon Simple Workflow Service (Amazon SWF) makes it easy to build applications that use Amazon's cloud to coordinate work across distributed components. In Amazon SWF, a task represents a logical unit of work that is performed by a component of your workflow. Coordinating tasks in a workflow involves managing intertask dependencies, scheduling, and concurrency in accordance with the logical flow of the application. Amazon SWF gives you full control over implementing tasks and coordinating them without worrying about underlying complexities such as tracking their progress and maintaining their state. This documentation serves as reference only. For a broader overview of the Amazon SWF programming model, see the Amazon SWF Developer Guide . This document was last published on May 14, 2025. API Version 2012-01-25 1 Amazon Simple Workflow Service API Reference Actions The following actions are supported: • CountClosedWorkflowExecutions • CountOpenWorkflowExecutions • CountPendingActivityTasks • CountPendingDecisionTasks • DeleteActivityType • DeleteWorkflowType • DeprecateActivityType • DeprecateDomain • DeprecateWorkflowType • DescribeActivityType • DescribeDomain • DescribeWorkflowExecution • DescribeWorkflowType • GetWorkflowExecutionHistory • ListActivityTypes • ListClosedWorkflowExecutions • ListDomains • ListOpenWorkflowExecutions • ListTagsForResource • ListWorkflowTypes • PollForActivityTask • PollForDecisionTask • RecordActivityTaskHeartbeat • RegisterActivityType • RegisterDomain • RegisterWorkflowType • RequestCancelWorkflowExecution API Version 2012-01-25 2 Amazon Simple Workflow Service API Reference • RespondActivityTaskCanceled • RespondActivityTaskCompleted • RespondActivityTaskFailed • RespondDecisionTaskCompleted • SignalWorkflowExecution • StartWorkflowExecution • TagResource • TerminateWorkflowExecution • UndeprecateActivityType • UndeprecateDomain • UndeprecateWorkflowType • UntagResource API Version 2012-01-25 3 Amazon Simple Workflow Service API Reference CountClosedWorkflowExecutions Returns the number of closed workflow executions within the given domain that meet the specified filtering criteria. Note This operation is eventually consistent. The results are best effort and may not exactly reflect recent updates and changes. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • tagFilter.tag: String constraint. The key is swf:tagFilter.tag. • typeFilter.name: String constraint. The key is swf:typeFilter.name. • typeFilter.version: String constraint. The key is swf:typeFilter.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "closeStatusFilter": { "status": "string" }, "closeTimeFilter": { "latestDate": number, "oldestDate": number }, CountClosedWorkflowExecutions API Version 2012-01-25 4 Amazon Simple Workflow Service API Reference "domain": "string", "executionFilter": { "workflowId": "string" }, "startTimeFilter": { "latestDate": number, "oldestDate": number }, "tagFilter": { "tag": "string" }, "typeFilter": { "name": "string", "version": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. closeStatusFilter If specified, only workflow executions that match this close status are counted. This filter has an affect only if executionStatus is specified as CLOSED. Note closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: CloseStatusFilter object Required: No closeTimeFilter If specified, only workflow executions that meet the close time criteria of the filter are counted. Request Parameters API Version 2012-01-25 5 Amazon Simple Workflow Service API Reference Note startTimeFilter and closeTimeFilter are mutually exclusive. You must specify one of these in a request but not both. Type: ExecutionTimeFilter object Required: No domain The name of the domain containing the workflow executions to count. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes executionFilter If specified, only workflow executions matching the WorkflowId in the filter are counted. Note closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: WorkflowExecutionFilter object Required: No startTimeFilter If specified, only workflow executions that meet
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Service API Reference Note startTimeFilter and closeTimeFilter are mutually exclusive. You must specify one of these in a request but not both. Type: ExecutionTimeFilter object Required: No domain The name of the domain containing the workflow executions to count. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes executionFilter If specified, only workflow executions matching the WorkflowId in the filter are counted. Note closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: WorkflowExecutionFilter object Required: No startTimeFilter If specified, only workflow executions that meet the start time criteria of the filter are counted. Note startTimeFilter and closeTimeFilter are mutually exclusive. You must specify one of these in a request but not both. Request Parameters API Version 2012-01-25 6 Amazon Simple Workflow Service API Reference Type: ExecutionTimeFilter object Required: No tagFilter If specified, only executions that have a tag that matches the filter are counted. Note closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: TagFilter object Required: No typeFilter If specified, indicates the type of the workflow executions to be counted. Note closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: WorkflowTypeFilter object Required: No Response Syntax { "count": number, "truncated": boolean } Response Elements If the action is successful, the service sends back an HTTP 200 response. Response Syntax API Version 2012-01-25 7 Amazon Simple Workflow Service API Reference The following data is returned in JSON format by the service. count The number of workflow executions. Type: Integer Valid Range: Minimum value of 0. truncated If set to true, indicates that the actual count was more than the maximum supported by this API and the count returned is the truncated value. Type: Boolean Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples CountClosedWorkflowExecutions Example This example illustrates one usage of CountClosedWorkflowExecutions. Errors API Version 2012-01-25 8 Amazon Simple Workflow Service Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com API Reference User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 02:42:47 GMT X-Amz-Target: SimpleWorkflowService.CountClosedWorkflowExecutions Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content-Encoding,Signature=jFS74utjeATV7vj72CWdLToPCKW0RQse6OEDkafB +SA= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 157 Pragma: no-cache Cache-Control: no-cache { "domain": "867530901", "activityType": { "version": "1.0", "name": "activityVerify" } } Sample Response HTTP/1.1 200 OK Content-Length: 29 Content-Type: application/json x-amzn-RequestId: 9bfad387-3f22-11e1-9914-a356b6ea8bdf { "count":3, "truncated":false } Examples API Version 2012-01-25 9 Amazon Simple Workflow Service See Also API Reference For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 10 Amazon Simple Workflow Service API Reference CountOpenWorkflowExecutions Returns the number of open workflow executions within the given domain that meet the specified filtering criteria. Note This operation is eventually consistent. The results are best effort and may not exactly reflect recent updates and changes. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • tagFilter.tag: String constraint. The key is swf:tagFilter.tag. • typeFilter.name: String constraint. The key is swf:typeFilter.name. • typeFilter.version: String constraint. The key is swf:typeFilter.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "executionFilter": { "workflowId": "string" }, "startTimeFilter": { "latestDate": number, "oldestDate": number }, CountOpenWorkflowExecutions API Version 2012-01-25 11 Amazon Simple Workflow Service
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key is swf:tagFilter.tag. • typeFilter.name: String constraint. The key is swf:typeFilter.name. • typeFilter.version: String constraint. The key is swf:typeFilter.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "executionFilter": { "workflowId": "string" }, "startTimeFilter": { "latestDate": number, "oldestDate": number }, CountOpenWorkflowExecutions API Version 2012-01-25 11 Amazon Simple Workflow Service API Reference "tagFilter": { "tag": "string" }, "typeFilter": { "name": "string", "version": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain containing the workflow executions to count. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes executionFilter If specified, only workflow executions matching the WorkflowId in the filter are counted. Note executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: WorkflowExecutionFilter object Required: No startTimeFilter Specifies the start time criteria that workflow executions must meet in order to be counted. Type: ExecutionTimeFilter object Request Parameters API Version 2012-01-25 12 Amazon Simple Workflow Service Required: Yes tagFilter API Reference If specified, only executions that have a tag that matches the filter are counted. Note executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: TagFilter object Required: No typeFilter Specifies the type of the workflow executions to be counted. Note executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: WorkflowTypeFilter object Required: No Response Syntax { "count": number, "truncated": boolean } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. Response Syntax API Version 2012-01-25 13 Amazon Simple Workflow Service count The number of workflow executions. Type: Integer Valid Range: Minimum value of 0. truncated API Reference If set to true, indicates that the actual count was more than the maximum supported by this API and the count returned is the truncated value. Type: Boolean Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples CountOpenWorkflowExecutions Example This example illustrates one usage of CountOpenWorkflowExecutions. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com Errors API Version 2012-01-25 14 Amazon Simple Workflow Service API Reference User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sat, 14 Jan 2012 23:13:29 GMT X-Amz-Target: SimpleWorkflowService.CountOpenWorkflowExecutions Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content-Encoding,Signature=3v6shiGzWukq4KiX/5HFMIUF/w5qajhW4dp +6AKyOtY= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 150 Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "startTimeFilter": {"oldestDate": 1325376070, "latestDate": 1356998399}, "tagFilter": {"tag": "ricoh-the-dog"} } Sample Response HTTP/1.1 200 OK Content-Length: 29 Content-Type: application/json x-amzn-RequestId: 5ea6789e-3f05-11e1-9e8f-57bb03e21482 {"count":1,"truncated":false} See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: See Also API Version 2012-01-25 15 API Reference Amazon Simple Workflow Service • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 16 Amazon Simple Workflow Service API Reference CountPendingActivityTasks Returns the estimated number of activity tasks in the specified task list. The count returned is an approximation and isn't guaranteed to be exact. If you specify a task list that no activity task was ever scheduled in then 0 is returned. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the taskList.name parameter by using a Condition element with the swf:taskList.name key to allow the action to access only certain task lists. If the caller doesn't
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isn't guaranteed to be exact. If you specify a task list that no activity task was ever scheduled in then 0 is returned. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the taskList.name parameter by using a Condition element with the swf:taskList.name key to allow the action to access only certain task lists. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "taskList": { "name": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain that contains the task list. CountPendingActivityTasks API Version 2012-01-25 17 Amazon Simple Workflow Service Type: String API Reference Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes taskList The name of the task list. Type: TaskList object Required: Yes Response Syntax { "count": number, "truncated": boolean } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. count The number of tasks in the task list. Type: Integer Valid Range: Minimum value of 0. truncated If set to true, indicates that the actual count was more than the maximum supported by this API and the count returned is the truncated value. Type: Boolean Response Syntax API Version 2012-01-25 18 Amazon Simple Workflow Service API Reference Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples CountPendingActivityTasks Example This example illustrates one usage of CountPendingActivityTasks. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Mon, 16 Jan 2012 03:29:28 GMT X-Amz-Target: SimpleWorkflowService.CountPendingActivityTasks Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Errors API Version 2012-01-25 19 Amazon Simple Workflow Service Date;X-Amz-Target;Content- Encoding,Signature=eCNiyyl5qmP0gGQ0hM8LqeRzxEvVZ0LAjE4oxVzzk9w= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html API Reference Content-Length: 70 Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "taskList": {"name": "specialTaskList"} } Sample Response HTTP/1.1 200 OK Content-Length: 29 Content-Type: application/json x-amzn-RequestId: 4b977c76-3ff2-11e1-a23a-99d60383ae71 {"count":1,"truncated":false} See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 20 Amazon Simple Workflow Service API Reference CountPendingDecisionTasks Returns the estimated number of decision tasks in the specified task list. The count returned is an approximation and isn't guaranteed to be exact. If you specify a task list that no decision task was ever scheduled in then 0 is returned. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the taskList.name parameter by using a Condition element with the swf:taskList.name key to allow the action to access only certain task lists. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "taskList": { "name": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name
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to access only certain task lists. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "taskList": { "name": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain that contains the task list. CountPendingDecisionTasks API Version 2012-01-25 21 Amazon Simple Workflow Service Type: String API Reference Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes taskList The name of the task list. Type: TaskList object Required: Yes Response Syntax { "count": number, "truncated": boolean } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. count The number of tasks in the task list. Type: Integer Valid Range: Minimum value of 0. truncated If set to true, indicates that the actual count was more than the maximum supported by this API and the count returned is the truncated value. Type: Boolean Response Syntax API Version 2012-01-25 22 Amazon Simple Workflow Service API Reference Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples CountPendingDecisionTasks Example This example illustrates one usage of CountPendingDecisionTasks. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 23:25:57 GMT X-Amz-Target: SimpleWorkflowService.CountPendingDecisionTasks Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X- Errors API Version 2012-01-25 23 Amazon Simple Workflow Service API Reference Amz-Date;X-Amz-Target;Content-Encoding,Signature=i9tUkWnZBLfn/ T6BOymajCtwArAll6Stuh1x2C4dbsE= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 70 Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "taskList": {"name": "specialTaskList"} } Sample Response HTTP/1.1 200 OK Content-Length: 29 Content-Type: application/json x-amzn-RequestId: 4718a364-3fd0-11e1-9914-a356b6ea8bdf {"count": 2, "truncated": false} See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 24 Amazon Simple Workflow Service DeleteActivityType Deletes the specified activity type. API Reference Note: Prior to deletion, activity types must first be deprecated. After an activity type has been deleted, you cannot schedule new activities of that type. Activities that started before the type was deleted will continue to run. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • activityType.name: String constraint. The key is swf:activityType.name. • activityType.version: String constraint. The key is swf:activityType.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "activityType": { "name": "string", "version": "string" }, "domain": "string" } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. DeleteActivityType API Version 2012-01-25 25 Amazon Simple Workflow Service activityType The activity type to delete. Type: ActivityType object Required: Yes domain API Reference The name of the domain in which the activity type is registered. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes Response Elements If the action is successful, the service sends back an HTTP 200 response with an empty HTTP body. Errors For information about the errors that are common to all actions, see
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that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. DeleteActivityType API Version 2012-01-25 25 Amazon Simple Workflow Service activityType The activity type to delete. Type: ActivityType object Required: Yes domain API Reference The name of the domain in which the activity type is registered. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes Response Elements If the action is successful, the service sends back an HTTP 200 response with an empty HTTP body. Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 TypeNotDeprecatedFault Returned when the resource type has not been deprecated. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. Response Elements API Version 2012-01-25 26 Amazon Simple Workflow Service HTTP Status Code: 400 See Also API Reference For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 27 Amazon Simple Workflow Service API Reference DeleteWorkflowType Deletes the specified workflow type. Note: Prior to deletion, workflow types must first be deprecated. After a workflow type has been deleted, you cannot create new executions of that type. Executions that started before the type was deleted will continue to run. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • workflowType.name: String constraint. The key is swf:workflowType.name. • workflowType.version: String constraint. The key is swf:workflowType.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "workflowType": { "name": "string", "version": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. DeleteWorkflowType API Version 2012-01-25 28 Amazon Simple Workflow Service domain API Reference The name of the domain in which the workflow type is registered. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes workflowType The workflow type to delete. Type: WorkflowType object Required: Yes Response Elements If the action is successful, the service sends back an HTTP 200 response with an empty HTTP body. Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 TypeNotDeprecatedFault Returned when the resource type has not been deprecated. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. Response Elements API Version 2012-01-25 29 Amazon Simple Workflow Service HTTP Status Code: 400 See Also API Reference For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 30 Amazon Simple Workflow Service API Reference DeprecateActivityType Deprecates the specified activity type. After an activity type has been deprecated, you cannot create new tasks of that activity type. Tasks of this type that were scheduled before the type was deprecated continue to run. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource
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V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 30 Amazon Simple Workflow Service API Reference DeprecateActivityType Deprecates the specified activity type. After an activity type has been deprecated, you cannot create new tasks of that activity type. Tasks of this type that were scheduled before the type was deprecated continue to run. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • activityType.name: String constraint. The key is swf:activityType.name. • activityType.version: String constraint. The key is swf:activityType.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "activityType": { "name": "string", "version": "string" }, "domain": "string" } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. DeprecateActivityType API Version 2012-01-25 31 Amazon Simple Workflow Service activityType The activity type to deprecate. Type: ActivityType object Required: Yes domain API Reference The name of the domain in which the activity type is registered. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes Response Elements If the action is successful, the service sends back an HTTP 200 response with an empty HTTP body. Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 TypeDeprecatedFault Returned when the specified activity or workflow type was already deprecated. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Response Elements API Version 2012-01-25 32 API Reference Amazon Simple Workflow Service Examples DeprecateActivityType Example This example illustrates one usage of DeprecateActivityType. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Mon, 16 Jan 2012 05:01:06 GMT X-Amz-Target: SimpleWorkflowService.DeprecateActivityType Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content-Encoding,Signature=iX/ mNMtNH6IaSNwfZq9hHOhDlLnp7buuj9tO93kRIrQ= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 95 Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "activityType": {"name": "activityVerify", "version": "1.0"} } Sample Response HTTP/1.1 200 OK Content-Length: 0 Content-Type: application/json Examples API Version 2012-01-25 33 Amazon Simple Workflow Service API Reference x-amzn-RequestId: 191ee17e-3fff-11e1-a23a-99d60383ae71 See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 34 Amazon Simple Workflow Service DeprecateDomain API Reference Deprecates the specified domain. After a domain has been deprecated it cannot be used to create new workflow executions or register new types. However, you can still use visibility actions on this domain. Deprecating a domain also deprecates all activity and workflow types registered in the domain. Executions that were started before the domain was deprecated continues to run. Note This operation is eventually consistent. The results are best effort and may not exactly reflect recent updates and changes. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • You cannot use an IAM policy to constrain this action's parameters. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF
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this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • You cannot use an IAM policy to constrain this action's parameters. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "name": "string" } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. DeprecateDomain API Version 2012-01-25 35 API Reference Amazon Simple Workflow Service name The name of the domain to deprecate. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes Response Elements If the action is successful, the service sends back an HTTP 200 response with an empty HTTP body. Errors For information about the errors that are common to all actions, see Common Errors. DomainDeprecatedFault Returned when the specified domain has been deprecated. HTTP Status Code: 400 OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples DeprecateDomain Example This example illustrates one usage of DeprecateDomain. Response Elements API Version 2012-01-25 36 Amazon Simple Workflow Service Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com API Reference User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Mon, 16 Jan 2012 05:07:47 GMT X-Amz-Target: SimpleWorkflowService.DeprecateDomain Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content- Encoding,Signature=BkJDtbH9uZvrarqXTkBEYuYHO7PPygRI8ykV29Dz/5M= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 21 Pragma: no-cache Cache-Control: no-cache {"name": "867530901"} Sample Response HTTP/1.1 200 OK Content-Length: 0 Content-Type: application/json x-amzn-RequestId: 0800c01a-4000-11e1-9914-a356b6ea8bdf See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET See Also API Version 2012-01-25 37 API Reference Amazon Simple Workflow Service • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 38 Amazon Simple Workflow Service API Reference DeprecateWorkflowType Deprecates the specified workflow type. After a workflow type has been deprecated, you cannot create new executions of that type. Executions that were started before the type was deprecated continues to run. A deprecated workflow type may still be used when calling visibility actions. Note This operation is eventually consistent. The results are best effort and may not exactly reflect recent updates and changes. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • workflowType.name: String constraint. The key is swf:workflowType.name. • workflowType.version: String constraint. The key is swf:workflowType.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "workflowType": { "name": "string", "version": "string" } } DeprecateWorkflowType API Version 2012-01-25 39 Amazon Simple Workflow Service Request Parameters API Reference For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain in which the workflow type is registered. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes workflowType The workflow type to deprecate. Type: WorkflowType object Required: Yes Response Elements If the action is successful, the service sends back an HTTP 200 response with an empty HTTP body. Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the
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For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain in which the workflow type is registered. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes workflowType The workflow type to deprecate. Type: WorkflowType object Required: Yes Response Elements If the action is successful, the service sends back an HTTP 200 response with an empty HTTP body. Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 TypeDeprecatedFault Returned when the specified activity or workflow type was already deprecated. HTTP Status Code: 400 Request Parameters API Version 2012-01-25 40 Amazon Simple Workflow Service UnknownResourceFault API Reference Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples DeprecateWorkflowType Example This example illustrates one usage of DeprecateWorkflowType. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Mon, 16 Jan 2012 05:04:47 GMT X-Amz-Target: SimpleWorkflowService.DeprecateWorkflowType Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X- Amz-Date;X-Amz-Target;Content-Encoding,Signature=BGrr1djQvp+YLq3ci2ffpK8KWhZm/ PakBL2fFhc3zds= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 102 Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "workflowType": Examples API Version 2012-01-25 41 Amazon Simple Workflow Service API Reference {"name": "customerOrderWorkflow", "version": "1.0"} } Sample Response HTTP/1.1 200 OK Content-Length: 0 Content-Type: application/json x-amzn-RequestId: 9c8d6d3b-3fff-11e1-9e8f-57bb03e21482 See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 42 Amazon Simple Workflow Service API Reference DescribeActivityType Returns information about the specified activity type. This includes configuration settings provided when the type was registered and other general information about the type. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • activityType.name: String constraint. The key is swf:activityType.name. • activityType.version: String constraint. The key is swf:activityType.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "activityType": { "name": "string", "version": "string" }, "domain": "string" } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. DescribeActivityType API Version 2012-01-25 43 Amazon Simple Workflow Service activityType API Reference The activity type to get information about. Activity types are identified by the name and version that were supplied when the activity was registered. Type: ActivityType object Required: Yes domain The name of the domain in which the activity type is registered. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes Response Syntax { "configuration": { "defaultTaskHeartbeatTimeout": "string", "defaultTaskList": { "name": "string" }, "defaultTaskPriority": "string", "defaultTaskScheduleToCloseTimeout": "string", "defaultTaskScheduleToStartTimeout": "string", "defaultTaskStartToCloseTimeout": "string" }, "typeInfo": { "activityType": { "name": "string", "version": "string" }, "creationDate": number, "deprecationDate": number, "description": "string", "status": "string" } } Response Syntax API Version 2012-01-25 44 Amazon Simple Workflow Service Response Elements API Reference If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. configuration The configuration settings registered with the activity type. Type: ActivityTypeConfiguration object typeInfo General information about the activity type. The status of activity type (returned in the ActivityTypeInfo structure) can be one of the following. • REGISTERED – The type is registered and available. Workers supporting this type should be running. • DEPRECATED – The type was deprecated using DeprecateActivityType, but is still in use. You should keep workers supporting this type running. You cannot create new tasks of this type. Type: ActivityTypeInfo object
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back an HTTP 200 response. The following data is returned in JSON format by the service. configuration The configuration settings registered with the activity type. Type: ActivityTypeConfiguration object typeInfo General information about the activity type. The status of activity type (returned in the ActivityTypeInfo structure) can be one of the following. • REGISTERED – The type is registered and available. Workers supporting this type should be running. • DEPRECATED – The type was deprecated using DeprecateActivityType, but is still in use. You should keep workers supporting this type running. You cannot create new tasks of this type. Type: ActivityTypeInfo object Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Response Elements API Version 2012-01-25 45 API Reference Amazon Simple Workflow Service Examples DescribeActivityType Example This example illustrates one usage of DescribeActivityType. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 03:04:10 GMT X-Amz-Target: SimpleWorkflowService.DescribeActivityType Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X- Amz-Date;X-Amz-Target;Content-Encoding,Signature=XiGRwOZNLt +ic3VBWvIlRGdcFcRJVSE8J7zyZLU3oXg= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 95 Pragma: no-cache Cache-Control: no-cache { "domain": "867530901", "activityType": { "version": "1.0", "name": "activityVerify" } } Sample Response HTTP/1.1 200 OK Examples API Version 2012-01-25 46 Amazon Simple Workflow Service Content-Length: 387 Content-Type: application/json x-amzn-RequestId: 98d56ff5-3f25-11e1-9b11-7182192d0b57 API Reference { "configuration": { "defaultTaskHeartbeatTimeout": "120", "defaultTaskList": {"name": "mainTaskList"}, "defaultTaskPriority", "100", "defaultTaskScheduleToCloseTimeout": "900", "defaultTaskScheduleToStartTimeout": "300", "defaultTaskStartToCloseTimeout": "600" }, "typeInfo": { "activityType": {"name": "activityVerify", "version": "1.0"}, "creationDate": 1326586446.471, "description": "Verify the customer credit", "status": "REGISTERED" } } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 47 Amazon Simple Workflow Service DescribeDomain API Reference Returns information about the specified domain, including description and status. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • You cannot use an IAM policy to constrain this action's parameters. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "name": "string" } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. name The name of the domain to describe. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes DescribeDomain API Version 2012-01-25 48 Amazon Simple Workflow Service Response Syntax { "configuration": { "workflowExecutionRetentionPeriodInDays": "string" }, API Reference "domainInfo": { "arn": "string", "description": "string", "name": "string", "status": "string" } } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. configuration The domain configuration. Currently, this includes only the domain's retention period. Type: DomainConfiguration object domainInfo The basic information about a domain, such as its name, status, and description. Type: DomainInfo object Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 Response Syntax API Version 2012-01-25 49 Amazon Simple Workflow Service UnknownResourceFault API Reference Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples DescribeDomain Example This example illustrates one usage of DescribeDomain. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729;
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when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 Response Syntax API Version 2012-01-25 49 Amazon Simple Workflow Service UnknownResourceFault API Reference Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples DescribeDomain Example This example illustrates one usage of DescribeDomain. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 03:13:33 GMT X-Amz-Target: SimpleWorkflowService.DescribeDomain Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content- Encoding,Signature=IFJtq3M366CHqMlTpyqYqd9z0ChCoKDC5SCJBsLifu4= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 21 Pragma: no-cache Cache-Control: no-cache {"name": "867530901"} Examples API Version 2012-01-25 50 API Reference Amazon Simple Workflow Service Sample Response HTTP/1.1 200 OK Content-Length: 137 Content-Type: application/json x-amzn-RequestId: e86a6779-3f26-11e1-9a27-0760db01a4a8 {"configuration": {"workflowExecutionRetentionPeriodInDays": "60"}, "domainInfo": {"description": "music", "name": "867530901", "status": "REGISTERED"} } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 51 Amazon Simple Workflow Service API Reference DescribeWorkflowExecution Returns information about the specified workflow execution including its type and some statistics. Note This operation is eventually consistent. The results are best effort and may not exactly reflect recent updates and changes. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • You cannot use an IAM policy to constrain this action's parameters. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "execution": { "runId": "string", "workflowId": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. DescribeWorkflowExecution API Version 2012-01-25 52 Amazon Simple Workflow Service domain API Reference The name of the domain containing the workflow execution. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes execution The workflow execution to describe. Type: WorkflowExecution object Required: Yes Response Syntax { "executionConfiguration": { "childPolicy": "string", "executionStartToCloseTimeout": "string", "lambdaRole": "string", "taskList": { "name": "string" }, "taskPriority": "string", "taskStartToCloseTimeout": "string" }, "executionInfo": { "cancelRequested": boolean, "closeStatus": "string", "closeTimestamp": number, "execution": { "runId": "string", "workflowId": "string" }, "executionStatus": "string", "parent": { "runId": "string", "workflowId": "string" Response Syntax API Version 2012-01-25 53 Amazon Simple Workflow Service API Reference }, "startTimestamp": number, "tagList": [ "string" ], "workflowType": { "name": "string", "version": "string" } }, "latestActivityTaskTimestamp": number, "latestExecutionContext": "string", "openCounts": { "openActivityTasks": number, "openChildWorkflowExecutions": number, "openDecisionTasks": number, "openLambdaFunctions": number, "openTimers": number } } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. executionConfiguration The configuration settings for this workflow execution including timeout values, tasklist etc. Type: WorkflowExecutionConfiguration object executionInfo Information about the workflow execution. Type: WorkflowExecutionInfo object latestActivityTaskTimestamp The time when the last activity task was scheduled for this workflow execution. You can use this information to determine if the workflow has not made progress for an unusually long period of time and might require a corrective action. Type: Timestamp Response Elements API Version 2012-01-25 54 Amazon Simple Workflow Service latestExecutionContext API Reference The latest executionContext provided by the decider for this workflow execution. A decider can provide an executionContext (a free-form string) when closing a decision task using RespondDecisionTaskCompleted. Type: String Length Constraints: Maximum length of 32768. openCounts The number of tasks for this workflow execution. This includes open and closed tasks of all types. Type: WorkflowExecutionOpenCounts object Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or
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decider for this workflow execution. A decider can provide an executionContext (a free-form string) when closing a decision task using RespondDecisionTaskCompleted. Type: String Length Constraints: Maximum length of 32768. openCounts The number of tasks for this workflow execution. This includes open and closed tasks of all types. Type: WorkflowExecutionOpenCounts object Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples DescribeWorkflowExecution Example This example illustrates one usage of DescribeWorkflowExecution. Errors API Version 2012-01-25 55 Amazon Simple Workflow Service Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com API Reference User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 02:05:18 GMT X-Amz-Target: SimpleWorkflowService.DescribeWorkflowExecution Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content- Encoding,Signature=ufQVcSkfUyGPLiS8xbkEBqEc2PmEEE/3Lb9Kr8yozs8= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 127 Pragma: no-cache Cache-Control: no-cache { "domain": "867530901", "execution": { "workflowId": "20110927-T-1", "runId": "06b8f87a-24b3-40b6-9ceb-9676f28e9493" } } Sample Response HTTP/1.1 200 OK Content-Length: 577 Content-Type: application/json x-amzn-RequestId: 5f85ef79-3f1d-11e1-9e8f-57bb03e21482 { "executionConfiguration": { Examples API Version 2012-01-25 56 Amazon Simple Workflow Service API Reference "executionStartToCloseTimeout": "3600", "childPolicy": "TERMINATE", "taskPriority": "100", "taskStartToCloseTimeout": "600", "taskList": { "name": "specialTaskList" } }, "openCounts": { "openTimers": 0, "openDecisionTasks": 1, "openActivityTasks": 0, "openChildWorkflowExecutions": 0 }, "executionInfo": { "execution": { "workflowId": "20110927-T-1", "runId": "06b8f87a-24b3-40b6-9ceb-9676f28e9493" }, "startTimestamp": 1326592619.474, "executionStatus": "OPEN", "workflowType": { "version": "1.0", "name": "customerOrderWorkflow" }, "cancelRequested": false, "tagList": [ "music purchase", "digital", "ricoh-the-dog" ] } } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ See Also API Version 2012-01-25 57 Amazon Simple Workflow Service • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 API Reference See Also API Version 2012-01-25 58 Amazon Simple Workflow Service API Reference DescribeWorkflowType Returns information about the specified workflow type. This includes configuration settings specified when the type was registered and other information such as creation date, current status, etc. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • workflowType.name: String constraint. The key is swf:workflowType.name. • workflowType.version: String constraint. The key is swf:workflowType.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "workflowType": { "name": "string", "version": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. DescribeWorkflowType API Version 2012-01-25 59 Amazon Simple Workflow Service domain API Reference The name of the domain in which this workflow type is registered. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes workflowType The workflow type to describe. Type: WorkflowType object Required: Yes Response Syntax { "configuration": { "defaultChildPolicy": "string", "defaultExecutionStartToCloseTimeout": "string", "defaultLambdaRole": "string", "defaultTaskList": { "name": "string" }, "defaultTaskPriority": "string", "defaultTaskStartToCloseTimeout": "string" }, "typeInfo": { "creationDate": number, "deprecationDate": number, "description": "string", "status": "string", "workflowType": { "name": "string", "version": "string" } } } Response Syntax API Version 2012-01-25 60 Amazon Simple Workflow Service Response Elements API Reference If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. configuration Configuration settings of the workflow type registered through RegisterWorkflowType Type: WorkflowTypeConfiguration object typeInfo General information about the workflow type. The status of the workflow type (returned in the WorkflowTypeInfo structure) can be one of the following. • REGISTERED – The type is registered and available. Workers supporting this type should be running. • DEPRECATED – The type was deprecated using DeprecateWorkflowType, but is still in use. You should keep workers supporting this type
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API Reference If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. configuration Configuration settings of the workflow type registered through RegisterWorkflowType Type: WorkflowTypeConfiguration object typeInfo General information about the workflow type. The status of the workflow type (returned in the WorkflowTypeInfo structure) can be one of the following. • REGISTERED – The type is registered and available. Workers supporting this type should be running. • DEPRECATED – The type was deprecated using DeprecateWorkflowType, but is still in use. You should keep workers supporting this type running. You cannot create new workflow executions of this type. Type: WorkflowTypeInfo object Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Response Elements API Version 2012-01-25 61 API Reference Amazon Simple Workflow Service Examples DescribeWorkflowType Example This example illustrates one usage of DescribeWorkflowType. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 22:40:40 GMT X-Amz-Target: SimpleWorkflowService.DescribeWorkflowType Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content- Encoding,Signature=iGt8t83OmrURqu0pKYbcW6mNdjXbFomevCBPUPQEbaM= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 102 Pragma: no-cache Cache-Control: no-cache { "domain": "867530901", "workflowType": { "version": "1.0", "name": "customerOrderWorkflow" } } Sample Response HTTP/1.1 200 OK Examples API Version 2012-01-25 62 Amazon Simple Workflow Service Content-Length: 348 Content-Type: application/json x-amzn-RequestId: f35a8e7f-3fc9-11e1-a23a-99d60383ae71 API Reference { "configuration": { "defaultExecutionStartToCloseTimeout": "3600", "defaultTaskStartToCloseTimeout": "600", "defaultTaskList": {"name": "mainTaskList"}, "defaultTaskPriority": "10" "defaultChildPolicy": "TERMINATE" }, "typeInfo": { "status": "REGISTERED", "creationDate": 1326481174.027, "description": "Handle customer orders", "workflowType": { "version": "1.0", "name": "customerOrderWorkflow" } } } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 63 Amazon Simple Workflow Service API Reference See Also API Version 2012-01-25 64 Amazon Simple Workflow Service API Reference GetWorkflowExecutionHistory Returns the history of the specified workflow execution. The results may be split into multiple pages. To retrieve subsequent pages, make the call again using the nextPageToken returned by the initial call. Note This operation is eventually consistent. The results are best effort and may not exactly reflect recent updates and changes. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • You cannot use an IAM policy to constrain this action's parameters. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "execution": { "runId": "string", "workflowId": "string" }, "maximumPageSize": number, "nextPageToken": "string", "reverseOrder": boolean } GetWorkflowExecutionHistory API Version 2012-01-25 65 Amazon Simple Workflow Service Request Parameters API Reference For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain containing the workflow execution. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes execution Specifies the workflow execution for which to return the history. Type: WorkflowExecution object Required: Yes maximumPageSize The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. Type: Integer Valid Range: Minimum value of 0. Maximum value of 1000. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next page. Keep all other arguments unchanged. Each pagination token expires after 24 hours. Using an expired pagination token will return a 400 error: "Specified token has exceeded its maximum lifetime". The
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Required: Yes maximumPageSize The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. Type: Integer Valid Range: Minimum value of 0. Maximum value of 1000. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next page. Keep all other arguments unchanged. Each pagination token expires after 24 hours. Using an expired pagination token will return a 400 error: "Specified token has exceeded its maximum lifetime". The configured maximumPageSize determines how many results can be returned in a single call. Request Parameters API Version 2012-01-25 66 Amazon Simple Workflow Service Type: String Length Constraints: Maximum length of 2048. Required: No reverseOrder API Reference When set to true, returns the events in reverse order. By default the results are returned in ascending order of the eventTimeStamp of the events. Type: Boolean Required: No Response Syntax { "events": [ { "activityTaskCanceledEventAttributes": { "details": "string", "latestCancelRequestedEventId": number, "scheduledEventId": number, "startedEventId": number }, "activityTaskCancelRequestedEventAttributes": { "activityId": "string", "decisionTaskCompletedEventId": number }, "activityTaskCompletedEventAttributes": { "result": "string", "scheduledEventId": number, "startedEventId": number }, "activityTaskFailedEventAttributes": { "details": "string", "reason": "string", "scheduledEventId": number, "startedEventId": number }, "activityTaskScheduledEventAttributes": { "activityId": "string", "activityType": { Response Syntax API Version 2012-01-25 67 Amazon Simple Workflow Service API Reference "name": "string", "version": "string" }, "control": "string", "decisionTaskCompletedEventId": number, "heartbeatTimeout": "string", "input": "string", "scheduleToCloseTimeout": "string", "scheduleToStartTimeout": "string", "startToCloseTimeout": "string", "taskList": { "name": "string" }, "taskPriority": "string" }, "activityTaskStartedEventAttributes": { "identity": "string", "scheduledEventId": number }, "activityTaskTimedOutEventAttributes": { "details": "string", "scheduledEventId": number, "startedEventId": number, "timeoutType": "string" }, "cancelTimerFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number, "timerId": "string" }, "cancelWorkflowExecutionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number }, "childWorkflowExecutionCanceledEventAttributes": { "details": "string", "initiatedEventId": number, "startedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", Response Syntax API Version 2012-01-25 68 Amazon Simple Workflow Service API Reference "version": "string" } }, "childWorkflowExecutionCompletedEventAttributes": { "initiatedEventId": number, "result": "string", "startedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "childWorkflowExecutionFailedEventAttributes": { "details": "string", "initiatedEventId": number, "reason": "string", "startedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "childWorkflowExecutionStartedEventAttributes": { "initiatedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "childWorkflowExecutionTerminatedEventAttributes": { "initiatedEventId": number, "startedEventId": number, Response Syntax API Version 2012-01-25 69 Amazon Simple Workflow Service API Reference "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "childWorkflowExecutionTimedOutEventAttributes": { "initiatedEventId": number, "startedEventId": number, "timeoutType": "string", "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "completeWorkflowExecutionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number }, "continueAsNewWorkflowExecutionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number }, "decisionTaskCompletedEventAttributes": { "executionContext": "string", "scheduledEventId": number, "startedEventId": number, "taskList": { "name": "string" }, "taskListScheduleToStartTimeout": "string" }, "decisionTaskScheduledEventAttributes": { "scheduleToStartTimeout": "string", "startToCloseTimeout": "string", "taskList": { "name": "string" Response Syntax API Version 2012-01-25 70 Amazon Simple Workflow Service API Reference }, "taskPriority": "string" }, "decisionTaskStartedEventAttributes": { "identity": "string", "scheduledEventId": number }, "decisionTaskTimedOutEventAttributes": { "scheduledEventId": number, "startedEventId": number, "timeoutType": "string" }, "eventId": number, "eventTimestamp": number, "eventType": "string", "externalWorkflowExecutionCancelRequestedEventAttributes": { "initiatedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" } }, "externalWorkflowExecutionSignaledEventAttributes": { "initiatedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" } }, "failWorkflowExecutionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number }, "lambdaFunctionCompletedEventAttributes": { "result": "string", "scheduledEventId": number, "startedEventId": number }, "lambdaFunctionFailedEventAttributes": { "details": "string", "reason": "string", "scheduledEventId": number, "startedEventId": number }, Response Syntax API Version 2012-01-25 71 Amazon Simple Workflow Service API Reference "lambdaFunctionScheduledEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "id": "string", "input": "string", "name": "string", "startToCloseTimeout": "string" }, "lambdaFunctionStartedEventAttributes": { "scheduledEventId": number }, "lambdaFunctionTimedOutEventAttributes": { "scheduledEventId": number, "startedEventId": number, "timeoutType": "string" }, "markerRecordedEventAttributes": { "decisionTaskCompletedEventId": number, "details": "string", "markerName": "string" }, "recordMarkerFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number, "markerName": "string" }, "requestCancelActivityTaskFailedEventAttributes": { "activityId": "string", "cause": "string", "decisionTaskCompletedEventId": number }, "requestCancelExternalWorkflowExecutionFailedEventAttributes": { "cause": "string", "control": "string", "decisionTaskCompletedEventId": number, "initiatedEventId": number, "runId": "string", "workflowId": "string" }, "requestCancelExternalWorkflowExecutionInitiatedEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "runId": "string", "workflowId": "string" Response Syntax API Version 2012-01-25 72 API Reference Amazon Simple Workflow Service }, "scheduleActivityTaskFailedEventAttributes": { "activityId": "string", "activityType": { "name": "string", "version": "string" }, "cause": "string", "decisionTaskCompletedEventId": number }, "scheduleLambdaFunctionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number, "id": "string", "name": "string" }, "signalExternalWorkflowExecutionFailedEventAttributes": { "cause": "string", "control": "string", "decisionTaskCompletedEventId": number, "initiatedEventId": number, "runId": "string", "workflowId": "string" }, "signalExternalWorkflowExecutionInitiatedEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "input": "string", "runId": "string", "signalName": "string", "workflowId": "string" }, "startChildWorkflowExecutionFailedEventAttributes": { "cause": "string", "control": "string", "decisionTaskCompletedEventId": number, "initiatedEventId": number, "workflowId": "string", "workflowType": { "name": "string", "version": "string" } }, "startChildWorkflowExecutionInitiatedEventAttributes": { Response Syntax API Version 2012-01-25 73 Amazon Simple Workflow Service API Reference "childPolicy": "string", "control": "string", "decisionTaskCompletedEventId": number, "executionStartToCloseTimeout": "string", "input": "string", "lambdaRole": "string", "tagList": [ "string" ], "taskList": { "name": "string" }, "taskPriority": "string", "taskStartToCloseTimeout": "string", "workflowId": "string", "workflowType":
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"string", "decisionTaskCompletedEventId": number, "id": "string", "name": "string" }, "signalExternalWorkflowExecutionFailedEventAttributes": { "cause": "string", "control": "string", "decisionTaskCompletedEventId": number, "initiatedEventId": number, "runId": "string", "workflowId": "string" }, "signalExternalWorkflowExecutionInitiatedEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "input": "string", "runId": "string", "signalName": "string", "workflowId": "string" }, "startChildWorkflowExecutionFailedEventAttributes": { "cause": "string", "control": "string", "decisionTaskCompletedEventId": number, "initiatedEventId": number, "workflowId": "string", "workflowType": { "name": "string", "version": "string" } }, "startChildWorkflowExecutionInitiatedEventAttributes": { Response Syntax API Version 2012-01-25 73 Amazon Simple Workflow Service API Reference "childPolicy": "string", "control": "string", "decisionTaskCompletedEventId": number, "executionStartToCloseTimeout": "string", "input": "string", "lambdaRole": "string", "tagList": [ "string" ], "taskList": { "name": "string" }, "taskPriority": "string", "taskStartToCloseTimeout": "string", "workflowId": "string", "workflowType": { "name": "string", "version": "string" } }, "startLambdaFunctionFailedEventAttributes": { "cause": "string", "message": "string", "scheduledEventId": number }, "startTimerFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number, "timerId": "string" }, "timerCanceledEventAttributes": { "decisionTaskCompletedEventId": number, "startedEventId": number, "timerId": "string" }, "timerFiredEventAttributes": { "startedEventId": number, "timerId": "string" }, "timerStartedEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "startToFireTimeout": "string", "timerId": "string" }, "workflowExecutionCanceledEventAttributes": { Response Syntax API Version 2012-01-25 74 Amazon Simple Workflow Service API Reference "decisionTaskCompletedEventId": number, "details": "string" }, "workflowExecutionCancelRequestedEventAttributes": { "cause": "string", "externalInitiatedEventId": number, "externalWorkflowExecution": { "runId": "string", "workflowId": "string" } }, "workflowExecutionCompletedEventAttributes": { "decisionTaskCompletedEventId": number, "result": "string" }, "workflowExecutionContinuedAsNewEventAttributes": { "childPolicy": "string", "decisionTaskCompletedEventId": number, "executionStartToCloseTimeout": "string", "input": "string", "lambdaRole": "string", "newExecutionRunId": "string", "tagList": [ "string" ], "taskList": { "name": "string" }, "taskPriority": "string", "taskStartToCloseTimeout": "string", "workflowType": { "name": "string", "version": "string" } }, "workflowExecutionFailedEventAttributes": { "decisionTaskCompletedEventId": number, "details": "string", "reason": "string" }, "workflowExecutionSignaledEventAttributes": { "externalInitiatedEventId": number, "externalWorkflowExecution": { "runId": "string", "workflowId": "string" }, Response Syntax API Version 2012-01-25 75 Amazon Simple Workflow Service API Reference "input": "string", "signalName": "string" }, "workflowExecutionStartedEventAttributes": { "childPolicy": "string", "continuedExecutionRunId": "string", "executionStartToCloseTimeout": "string", "input": "string", "lambdaRole": "string", "parentInitiatedEventId": number, "parentWorkflowExecution": { "runId": "string", "workflowId": "string" }, "tagList": [ "string" ], "taskList": { "name": "string" }, "taskPriority": "string", "taskStartToCloseTimeout": "string", "workflowType": { "name": "string", "version": "string" } }, "workflowExecutionTerminatedEventAttributes": { "cause": "string", "childPolicy": "string", "details": "string", "reason": "string" }, "workflowExecutionTimedOutEventAttributes": { "childPolicy": "string", "timeoutType": "string" } } ], "nextPageToken": "string" } Response Elements If the action is successful, the service sends back an HTTP 200 response. Response Elements API Version 2012-01-25 76 Amazon Simple Workflow Service API Reference The following data is returned in JSON format by the service. events The list of history events. Type: Array of HistoryEvent objects nextPageToken If a NextPageToken was returned by a previous call, there are more results available. To retrieve the next page of results, make the call again using the returned token in nextPageToken. Keep all other arguments unchanged. The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Errors API Version 2012-01-25 77 Amazon Simple Workflow Service Examples API Reference GetWorkflowExecutionHistory Example This example illustrates one usage of GetWorkflowExecutionHistory. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Mon, 16 Jan 2012 03:44:00 GMT X-Amz-Target: SimpleWorkflowService.GetWorkflowExecutionHistory Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content- Encoding,Signature=90GENeUWJbEAMWuVI0dcWatHjltMWddXfLjl0MbNOzM= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 175 Pragma: no-cache Cache-Control: no-cache { "maximumPageSize": 10, "domain": "867530901", "execution": { "workflowId": "20110927-T-1", "runId": "d29e60b5-fa71-4276-a4be-948b0adcd20b" }, "reverseOrder": true } Examples API Version 2012-01-25 78 Amazon Simple Workflow Service Sample Response HTTP/1.1 200 OK Content-Length: 2942 Content-Type: application/json x-amzn-RequestId: 5385723f-3ff4-11e1-b118-3bfa5e8e7fc3 { "nextPageToken": API Reference "AAAAKgAAAAEAAAAAAAAAATeTvAyvqlQz34ctbGhM5nglWmjzk0hGuHf0g4EO4CblQFku70ukjPgrAHy7Tnp7FaZ0okP8EEWnkfg8gi3Fqy/ WVrXyxQaa525D31cIq1owXK21CKR6SQ0Job87G8SHvvqvP7yjLGHlHrRGZUCbJgeEuV4Rp/yW +vKhc8dJ54x7wvpQMwZ+ssG6stTyX26vu1gIDuspk13UrDZa4TbLOFdM0aAocHe3xklKMtD/ B4ithem6BWm6CBl/UF7lMfNccwUYEityp1Kht/ YrcD9zbJkt1FSt4Y6pgt0njAh4FKRO9nyRyvLmbvgtQXEIQz8hdbjwj3xE1+9ocYwXOCAhVkRsh3OD6F8KHilKfdwg4Xz1jtLXOh4lsCecNb8dS7J9hbRErRbw3rh1Sv415U2Ye23OEfF4Jv7JznpmEyzuq8d2bMyOLjAInQVFK4t1tPo5FAhzdICCXBhRq6Wkt ++W9sRQXqqX/HTX5kNomHySZloylPuY5gL5zRj39frInfZk4EXWHwrI+18+erGIHO4nBQpMzO64dMP +A/KtVGCn59rAMmilD6wEE9rH8RuZ03Wkvm9yrJvjrI8/6358n8TMB8OcHoqILkMCAXYiIppnFlm +NWXVqxalHLKOrrNzEZM6qsz3Qj3HV1cpy9P7fnS9QAxrgsAYBoDmdOaFkS3ktAkRa0Sle8STfHi4zKbfIGS7rg==", "events": [ { "eventId": 11, "eventType": "WorkflowExecutionTimedOut", "eventTimestamp": 1326671603.102, "workflowExecutionTimedOutEventAttributes": { "timeoutType": "START_TO_CLOSE", "childPolicy": "TERMINATE" } }, { "eventId": 10, "eventType": "DecisionTaskScheduled", "decisionTaskScheduledEventAttributes": { "startToCloseTimeout": "600", "taskList": { "name": "specialTaskList" } }, "eventTimestamp": 1326670566.124 }, { "eventId": 9, "eventType": "ActivityTaskTimedOut", "activityTaskTimedOutEventAttributes": { "startedEventId": 0, "scheduledEventId": 8, Examples API Version 2012-01-25 79 Amazon Simple Workflow Service API Reference "timeoutType": "SCHEDULE_TO_START", }, "eventTimestamp": 1326670566.124 }, { "activityTaskScheduledEventAttributes": { "activityId": "verification-27", "activityType": { "version": "1.0", "name": "activityVerify" }, "control": "digital music", "decisionTaskCompletedEventId": 7, "heartbeatTimeout": "120", "input": "5634-0056-4367-0923,12/12,437", "scheduleToStartTimeout": "300", "scheduleToCloseTimeout": "900", "startToCloseTimeout": "600", "taskList": { "name": "specialTaskList" }, "taskPriority": "50" }, "eventId": 8, "eventTimestamp": 1326670266.115, "eventType": "ActivityTaskScheduled" }, { "eventId": 7, "eventType": "DecisionTaskCompleted", "decisionTaskCompletedEventAttributes": { "startedEventId": 6, "executionContext": "Black Friday", "scheduledEventId": 5 }, "eventTimestamp": 1326670266.103 }, { "eventId": 6, "decisionTaskStartedEventAttributes": { "scheduledEventId": 5, "identity": "Decider01" }, "eventTimestamp": 1326670161.497, Examples API Version 2012-01-25 80 Amazon Simple Workflow Service API Reference "eventType": "DecisionTaskStarted" }, { "eventId": 5, "eventType": "DecisionTaskScheduled", "decisionTaskScheduledEventAttributes": { "startToCloseTimeout":
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"timeoutType": "SCHEDULE_TO_START", }, "eventTimestamp": 1326670566.124 }, { "activityTaskScheduledEventAttributes": { "activityId": "verification-27", "activityType": { "version": "1.0", "name": "activityVerify" }, "control": "digital music", "decisionTaskCompletedEventId": 7, "heartbeatTimeout": "120", "input": "5634-0056-4367-0923,12/12,437", "scheduleToStartTimeout": "300", "scheduleToCloseTimeout": "900", "startToCloseTimeout": "600", "taskList": { "name": "specialTaskList" }, "taskPriority": "50" }, "eventId": 8, "eventTimestamp": 1326670266.115, "eventType": "ActivityTaskScheduled" }, { "eventId": 7, "eventType": "DecisionTaskCompleted", "decisionTaskCompletedEventAttributes": { "startedEventId": 6, "executionContext": "Black Friday", "scheduledEventId": 5 }, "eventTimestamp": 1326670266.103 }, { "eventId": 6, "decisionTaskStartedEventAttributes": { "scheduledEventId": 5, "identity": "Decider01" }, "eventTimestamp": 1326670161.497, Examples API Version 2012-01-25 80 Amazon Simple Workflow Service API Reference "eventType": "DecisionTaskStarted" }, { "eventId": 5, "eventType": "DecisionTaskScheduled", "decisionTaskScheduledEventAttributes": { "startToCloseTimeout": "600", "taskList": { "name": "specialTaskList" } }, "eventTimestamp": 1326668752.66 }, { "eventId": 4, "eventType": "DecisionTaskTimedOut", "eventTimestamp": 1326668752.66, "decisionTaskTimedOutEventAttributes": { "startedEventId": 3, "timeoutType": "START_TO_CLOSE", "scheduledEventId": 2 } }, { "eventId": 3, "decisionTaskStartedEventAttributes": { "scheduledEventId": 2, "identity": "Decider01" }, "eventTimestamp": 1326668152.648, "eventType": "DecisionTaskStarted" }, { "eventId": 2, "eventType": "DecisionTaskScheduled", "decisionTaskScheduledEventAttributes": { "startToCloseTimeout": "600", "taskList": { "name": "specialTaskList" } }, "eventTimestamp": 1326668003.094 } ] Examples API Version 2012-01-25 81 Amazon Simple Workflow Service API Reference } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 82 Amazon Simple Workflow Service ListActivityTypes API Reference Returns information about all activities registered in the specified domain that match the specified name and registration status. The result includes information like creation date, current status of the activity, etc. The results may be split into multiple pages. To retrieve subsequent pages, make the call again using the nextPageToken returned by the initial call. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • You cannot use an IAM policy to constrain this action's parameters. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "maximumPageSize": number, "name": "string", "nextPageToken": "string", "registrationStatus": "string", "reverseOrder": boolean } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain in which the activity types have been registered. ListActivityTypes API Version 2012-01-25 83 Amazon Simple Workflow Service Type: String API Reference Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes maximumPageSize The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. Type: Integer Valid Range: Minimum value of 0. Maximum value of 1000. Required: No name If specified, only lists the activity types that have this name. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next page. Keep all other arguments unchanged. Each pagination token expires after 24 hours. Using an expired pagination token will return a 400 error: "Specified token has exceeded its maximum lifetime". The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. Required: No Request Parameters API Version 2012-01-25 84 Amazon Simple Workflow Service registrationStatus API Reference Specifies the registration status of the activity types to list. Type: String Valid Values: REGISTERED | DEPRECATED Required: Yes reverseOrder When set to true, returns the results in reverse order. By default, the results are returned in ascending alphabetical order by name of the activity types. Type: Boolean Required: No Response Syntax { "nextPageToken": "string", "typeInfos": [ { "activityType": { "name": "string", "version": "string" }, "creationDate": number, "deprecationDate": number, "description": "string", "status": "string" } ] } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. Response Syntax API Version 2012-01-25 85 Amazon Simple Workflow Service nextPageToken API Reference If a NextPageToken was returned by a previous call, there are more results available.
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order. By default, the results are returned in ascending alphabetical order by name of the activity types. Type: Boolean Required: No Response Syntax { "nextPageToken": "string", "typeInfos": [ { "activityType": { "name": "string", "version": "string" }, "creationDate": number, "deprecationDate": number, "description": "string", "status": "string" } ] } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. Response Syntax API Version 2012-01-25 85 Amazon Simple Workflow Service nextPageToken API Reference If a NextPageToken was returned by a previous call, there are more results available. To retrieve the next page of results, make the call again using the returned token in nextPageToken. Keep all other arguments unchanged. The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. typeInfos List of activity type information. Type: Array of ActivityTypeInfo objects Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples ListActivityTypes Example This example illustrates one usage of ListActivityTypes. Errors API Version 2012-01-25 86 API Reference Amazon Simple Workflow Service Sample Request {"domain": "867530901", "registrationStatus": "REGISTERED", "maximumPageSize": 50, "reverseOrder": false} Sample Response HTTP/1.1 200 OK Content-Length: 171 Content-Type: application/json x-amzn-RequestId: 11b6fbeb-3f25-11e1-9e8f-57bb03e21482 {"typeInfos": [ {"activityType": {"name": "activityVerify", "version": "1.0"}, "creationDate": 1326586446.471, "description": "Verify the customer credit", "status": "REGISTERED"} ] } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 See Also API Version 2012-01-25 87 Amazon Simple Workflow Service • AWS SDK for Python • AWS SDK for Ruby V3 API Reference See Also API Version 2012-01-25 88 Amazon Simple Workflow Service API Reference ListClosedWorkflowExecutions Returns a list of closed workflow executions in the specified domain that meet the filtering criteria. The results may be split into multiple pages. To retrieve subsequent pages, make the call again using the nextPageToken returned by the initial call. Note This operation is eventually consistent. The results are best effort and may not exactly reflect recent updates and changes. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • tagFilter.tag: String constraint. The key is swf:tagFilter.tag. • typeFilter.name: String constraint. The key is swf:typeFilter.name. • typeFilter.version: String constraint. The key is swf:typeFilter.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "closeStatusFilter": { "status": "string" }, "closeTimeFilter": { "latestDate": number, "oldestDate": number ListClosedWorkflowExecutions API Version 2012-01-25 89 Amazon Simple Workflow Service API Reference }, "domain": "string", "executionFilter": { "workflowId": "string" }, "maximumPageSize": number, "nextPageToken": "string", "reverseOrder": boolean, "startTimeFilter": { "latestDate": number, "oldestDate": number }, "tagFilter": { "tag": "string" }, "typeFilter": { "name": "string", "version": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. closeStatusFilter If specified, only workflow executions that match this close status are listed. For example, if TERMINATED is specified, then only TERMINATED workflow executions are listed. Note closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: CloseStatusFilter object Required: No Request Parameters API Version 2012-01-25 90 Amazon Simple Workflow Service closeTimeFilter API Reference If specified, the workflow executions are included in the returned results based on whether their close times are within the range specified by this filter. Also, if this parameter is specified, the returned results are ordered by their close times. Note startTimeFilter and closeTimeFilter are mutually exclusive. You must specify one of these in a request but not both. Type: ExecutionTimeFilter object Required:
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closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: CloseStatusFilter object Required: No Request Parameters API Version 2012-01-25 90 Amazon Simple Workflow Service closeTimeFilter API Reference If specified, the workflow executions are included in the returned results based on whether their close times are within the range specified by this filter. Also, if this parameter is specified, the returned results are ordered by their close times. Note startTimeFilter and closeTimeFilter are mutually exclusive. You must specify one of these in a request but not both. Type: ExecutionTimeFilter object Required: No domain The name of the domain that contains the workflow executions to list. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes executionFilter If specified, only workflow executions matching the workflow ID specified in the filter are returned. Note closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: WorkflowExecutionFilter object Required: No Request Parameters API Version 2012-01-25 91 Amazon Simple Workflow Service maximumPageSize API Reference The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. Type: Integer Valid Range: Minimum value of 0. Maximum value of 100. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next page. Keep all other arguments unchanged. Each pagination token expires after 24 hours. Using an expired pagination token will return a 400 error: "Specified token has exceeded its maximum lifetime". The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. Required: No reverseOrder When set to true, returns the results in reverse order. By default the results are returned in descending order of the start or the close time of the executions. Type: Boolean Required: No startTimeFilter If specified, the workflow executions are included in the returned results based on whether their start times are within the range specified by this filter. Also, if this parameter is specified, the returned results are ordered by their start times. Request Parameters API Version 2012-01-25 92 Amazon Simple Workflow Service API Reference Note startTimeFilter and closeTimeFilter are mutually exclusive. You must specify one of these in a request but not both. Type: ExecutionTimeFilter object Required: No tagFilter If specified, only executions that have the matching tag are listed. Note closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: TagFilter object Required: No typeFilter If specified, only executions of the type specified in the filter are returned. Note closeStatusFilter, executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: WorkflowTypeFilter object Required: No Response Syntax { Response Syntax API Version 2012-01-25 93 Amazon Simple Workflow Service API Reference "executionInfos": [ { "cancelRequested": boolean, "closeStatus": "string", "closeTimestamp": number, "execution": { "runId": "string", "workflowId": "string" }, "executionStatus": "string", "parent": { "runId": "string", "workflowId": "string" }, "startTimestamp": number, "tagList": [ "string" ], "workflowType": { "name": "string", "version": "string" } } ], "nextPageToken": "string" } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. executionInfos The list of workflow information structures. Type: Array of WorkflowExecutionInfo objects nextPageToken If a NextPageToken was returned by a previous call, there are more results available. To retrieve the next page of results, make the call again using the returned token in nextPageToken. Keep all other arguments unchanged. Response Elements API Version 2012-01-25 94 Amazon Simple Workflow Service API Reference The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples ListClosedWorkflowExecutions Example This example illustrates one usage of ListClosedWorkflowExecutions. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Errors API Version 2012-01-25 95 Amazon Simple Workflow Service Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 02:51:01 GMT API Reference X-Amz-Target: SimpleWorkflowService.ListClosedWorkflowExecutions
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scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples ListClosedWorkflowExecutions Example This example illustrates one usage of ListClosedWorkflowExecutions. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Errors API Version 2012-01-25 95 Amazon Simple Workflow Service Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 02:51:01 GMT API Reference X-Amz-Target: SimpleWorkflowService.ListClosedWorkflowExecutions Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content-Encoding,Signature=WY9jGbf5E3F9smGJHANhEXz9VL+1oGVgNL0/ o7cBxQw= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 150 Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "closeTimeFilter": {"oldestDate": 1325376070, "latestDate": 1356998399}, "tagFilter": {"tag": "ricoh-the-dog"} } Sample Response HTTP/1.1 200 OK Content-Length: 1084 Content-Type: application/json x-amzn-RequestId: c28b4df4-3f23-11e1-9e8f-57bb03e21482 {"executionInfos": [ {"cancelRequested": false, "closeStatus": "TIMED_OUT", "closeTimestamp": 1326590754.654, "execution": {"runId": "c724e07a-b966-441f-a1c0-4831acbda1cd", "workflowId": "20110927-T-1"}, "executionStatus": "CLOSED", "startTimestamp": 1326587154.626, "tagList": ["music purchase", "digital", "ricoh-the-dog"], Examples API Version 2012-01-25 96 API Reference Amazon Simple Workflow Service "workflowType": {"name": "customerOrderWorkflow", "version": "1.0"} }, {"cancelRequested": false, "closeStatus": "TIMED_OUT", "closeTimestamp": 1326586831.628, "execution": {"runId": "f5ebbac6-941c-4342-ad69-dfd2f8be6689", "workflowId": "20110927-T-1"}, "executionStatus": "CLOSED", "startTimestamp": 1326585031.619, "tagList": ["music purchase", "digital", "ricoh-the-dog"], "workflowType": {"name": "customerOrderWorkflow", "version": "1.0"} }, {"cancelRequested": false, "closeStatus": "TIMED_OUT", "closeTimestamp": 1326582914.031, "execution": {"runId": "1e536162-f1ea-48b0-85f3-aade88eef2f7", "workflowId": "20110927-T-1"}, "executionStatus": "CLOSED", "startTimestamp": 1326581114.02, "tagList": ["music purchase", "digital", "ricoh-the-dog"], "workflowType": {"name": "customerOrderWorkflow", "version": "1.0"} } ] } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET See Also API Version 2012-01-25 97 API Reference Amazon Simple Workflow Service • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 98 Amazon Simple Workflow Service ListDomains API Reference Returns the list of domains registered in the account. The results may be split into multiple pages. To retrieve subsequent pages, make the call again using the nextPageToken returned by the initial call. Note This operation is eventually consistent. The results are best effort and may not exactly reflect recent updates and changes. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. The element must be set to arn:aws:swf::AccountID:domain/*, where AccountID is the account ID, with no dashes. • Use an Action element to allow or deny permission to call this action. • You cannot use an IAM policy to constrain this action's parameters. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "maximumPageSize": number, "nextPageToken": "string", "registrationStatus": "string", "reverseOrder": boolean } ListDomains API Version 2012-01-25 99 Amazon Simple Workflow Service Request Parameters API Reference For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. maximumPageSize The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. Type: Integer Valid Range: Minimum value of 0. Maximum value of 1000. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next page. Keep all other arguments unchanged. Each pagination token expires after 24 hours. Using an expired pagination token will return a 400 error: "Specified token has exceeded its maximum lifetime". The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. Required: No registrationStatus Specifies the registration status of the domains to list. Type: String Valid Values: REGISTERED | DEPRECATED Required: Yes Request Parameters API Version 2012-01-25 100 Amazon Simple Workflow Service reverseOrder API Reference When set to true, returns the results in reverse order. By default, the results are returned in ascending alphabetical order by name of the domains. Type: Boolean Required: No Response Syntax { "domainInfos": [ { "arn": "string", "description": "string", "name": "string", "status": "string" } ], "nextPageToken": "string" } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. domainInfos A list of DomainInfo structures. Type: Array of DomainInfo objects
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Required: Yes Request Parameters API Version 2012-01-25 100 Amazon Simple Workflow Service reverseOrder API Reference When set to true, returns the results in reverse order. By default, the results are returned in ascending alphabetical order by name of the domains. Type: Boolean Required: No Response Syntax { "domainInfos": [ { "arn": "string", "description": "string", "name": "string", "status": "string" } ], "nextPageToken": "string" } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. domainInfos A list of DomainInfo structures. Type: Array of DomainInfo objects nextPageToken If a NextPageToken was returned by a previous call, there are more results available. To retrieve the next page of results, make the call again using the returned token in nextPageToken. Keep all other arguments unchanged. The configured maximumPageSize determines how many results can be returned in a single call. Response Syntax API Version 2012-01-25 101 API Reference Amazon Simple Workflow Service Type: String Length Constraints: Maximum length of 2048. Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 Examples ListDomains Example This example illustrates one usage of ListDomains. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 03:09:58 GMT X-Amz-Target: SimpleWorkflowService.ListDomains Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X- Amz-Date;X-Amz-Target;Content-Encoding,Signature=ZCprC72dUxF9ca3w/ tbwKZ8lBQn0jaA4xOJqDF0uqMI= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Errors API Version 2012-01-25 102 API Reference Amazon Simple Workflow Service Content-Length: 86 Pragma: no-cache Cache-Control: no-cache {"registrationStatus": "REGISTERED", "maximumPageSize": 50, "reverseOrder": false} Sample Response HTTP/1.1 200 OK Content-Length: 568 Content-Type: application/json x-amzn-RequestId: 67e874cc-3f26-11e1-9b11-7182192d0b57 {"domainInfos": [ {"description": "music", "name": "867530901", "status": "REGISTERED"}, {"description": "music", "name": "867530902", "status": "REGISTERED"}, {"description": "", "name": "Demo", "status": "REGISTERED"}, {"description": "", "name": "DemoDomain", "status": "REGISTERED"}, {"description": "", "name": "Samples", "status": "REGISTERED"}, {"description": "", "name": "testDomain2", "status": "REGISTERED"}, {"description": "", "name": "testDomain3", "status": "REGISTERED"}, {"description": "", "name": "testDomain4", "status": "REGISTERED"}, {"description": "", "name": "zsxfvgsxcv", "status": "REGISTERED"} ] } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 See Also API Version 2012-01-25 103 Amazon Simple Workflow Service • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 API Reference See Also API Version 2012-01-25 104 Amazon Simple Workflow Service API Reference ListOpenWorkflowExecutions Returns a list of open workflow executions in the specified domain that meet the filtering criteria. The results may be split into multiple pages. To retrieve subsequent pages, make the call again using the nextPageToken returned by the initial call. Note This operation is eventually consistent. The results are best effort and may not exactly reflect recent updates and changes. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • tagFilter.tag: String constraint. The key is swf:tagFilter.tag. • typeFilter.name: String constraint. The key is swf:typeFilter.name. • typeFilter.version: String constraint. The key is swf:typeFilter.version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "executionFilter": { "workflowId": "string" }, "maximumPageSize": number, "nextPageToken": "string", "reverseOrder": boolean, ListOpenWorkflowExecutions API Version 2012-01-25 105 Amazon Simple Workflow Service API Reference "startTimeFilter": { "latestDate": number, "oldestDate": number }, "tagFilter": { "tag": "string" }, "typeFilter": { "name": "string", "version": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain that contains the workflow executions to list. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes executionFilter If specified, only workflow executions matching the workflow ID specified in the filter are returned. Note executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type:
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{ "tag": "string" }, "typeFilter": { "name": "string", "version": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain that contains the workflow executions to list. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes executionFilter If specified, only workflow executions matching the workflow ID specified in the filter are returned. Note executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: WorkflowExecutionFilter object Required: No Request Parameters API Version 2012-01-25 106 Amazon Simple Workflow Service maximumPageSize API Reference The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. Type: Integer Valid Range: Minimum value of 0. Maximum value of 100. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next page. Keep all other arguments unchanged. Each pagination token expires after 24 hours. Using an expired pagination token will return a 400 error: "Specified token has exceeded its maximum lifetime". The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. Required: No reverseOrder When set to true, returns the results in reverse order. By default the results are returned in descending order of the start time of the executions. Type: Boolean Required: No startTimeFilter Workflow executions are included in the returned results based on whether their start times are within the range specified by this filter. Type: ExecutionTimeFilter object Required: Yes Request Parameters API Version 2012-01-25 107 Amazon Simple Workflow Service tagFilter API Reference If specified, only executions that have the matching tag are listed. Note executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: TagFilter object Required: No typeFilter If specified, only executions of the type specified in the filter are returned. Note executionFilter, typeFilter and tagFilter are mutually exclusive. You can specify at most one of these in a request. Type: WorkflowTypeFilter object Required: No Response Syntax { "executionInfos": [ { "cancelRequested": boolean, "closeStatus": "string", "closeTimestamp": number, "execution": { "runId": "string", "workflowId": "string" }, "executionStatus": "string", Response Syntax API Version 2012-01-25 108 Amazon Simple Workflow Service API Reference "parent": { "runId": "string", "workflowId": "string" }, "startTimestamp": number, "tagList": [ "string" ], "workflowType": { "name": "string", "version": "string" } } ], "nextPageToken": "string" } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. executionInfos The list of workflow information structures. Type: Array of WorkflowExecutionInfo objects nextPageToken If a NextPageToken was returned by a previous call, there are more results available. To retrieve the next page of results, make the call again using the returned token in nextPageToken. Keep all other arguments unchanged. The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. Errors For information about the errors that are common to all actions, see Common Errors. Response Elements API Version 2012-01-25 109 Amazon Simple Workflow Service OperationNotPermittedFault API Reference Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples ListOpenWorkflowExecutions This example illustrates one usage of ListOpenWorkflowExecutions. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sat, 14 Jan 2012 23:51:04 GMT X-Amz-Target: SimpleWorkflowService.ListOpenWorkflowExecutions Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X- Amz-Date;X-Amz-Target;Content-Encoding,Signature=4kUhpZUp37PgpeOKHlWTsZi +Pq3Egw4mTkPNiEUgp28= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 151 Examples API Version 2012-01-25 110 API Reference Amazon Simple Workflow Service Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "startTimeFilter": {"oldestDate": 1325376070, "latestDate": 1356998399}, "tagFilter": {"tag": "music purchase"} } Sample Response HTTP/1.1 200 OK Content-Length: 313 Content-Type: application/json x-amzn-RequestId: 9efeff4b-3f0a-11e1-9e8f-57bb03e21482 { "executionInfos": [ { "cancelRequested": false, "execution": { "runId": "f5ebbac6-941c-4342-ad69-dfd2f8be6689", "workflowId": "20110927-T-1" }, "executionStatus": "OPEN", "startTimestamp": 1326585031.619, "tagList": [ "music purchase", "digital", "ricoh-the-dog" ], "workflowType": { "name": "customerOrderWorkflow", "version": "1.0" } } ] } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface See Also API Version 2012-01-25 111 API Reference Amazon Simple Workflow Service
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Simple Workflow Service Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "startTimeFilter": {"oldestDate": 1325376070, "latestDate": 1356998399}, "tagFilter": {"tag": "music purchase"} } Sample Response HTTP/1.1 200 OK Content-Length: 313 Content-Type: application/json x-amzn-RequestId: 9efeff4b-3f0a-11e1-9e8f-57bb03e21482 { "executionInfos": [ { "cancelRequested": false, "execution": { "runId": "f5ebbac6-941c-4342-ad69-dfd2f8be6689", "workflowId": "20110927-T-1" }, "executionStatus": "OPEN", "startTimestamp": 1326585031.619, "tagList": [ "music purchase", "digital", "ricoh-the-dog" ], "workflowType": { "name": "customerOrderWorkflow", "version": "1.0" } } ] } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface See Also API Version 2012-01-25 111 API Reference Amazon Simple Workflow Service • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 112 Amazon Simple Workflow Service API Reference ListTagsForResource List tags for a given domain. Request Syntax { "resourceArn": "string" } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. resourceArn The Amazon Resource Name (ARN) for the Amazon SWF domain. Type: String Length Constraints: Minimum length of 1. Maximum length of 1600. Required: Yes Response Syntax { "tags": [ { "key": "string", "value": "string" } ] } Response Elements If the action is successful, the service sends back an HTTP 200 response. ListTagsForResource API Version 2012-01-25 113 Amazon Simple Workflow Service API Reference The following data is returned in JSON format by the service. tags An array of tags associated with the domain. Type: Array of ResourceTag objects Errors For information about the errors that are common to all actions, see Common Errors. LimitExceededFault Returned by any operation if a system imposed limitation has been reached. To address this fault you should either clean up unused resources or increase the limit by contacting AWS. HTTP Status Code: 400 OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ Errors API Version 2012-01-25 114 Amazon Simple Workflow Service • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 API Reference See Also API Version 2012-01-25 115 Amazon Simple Workflow Service ListWorkflowTypes API Reference Returns information about workflow types in the specified domain. The results may be split into multiple pages that can be retrieved by making the call repeatedly. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • You cannot use an IAM policy to constrain this action's parameters. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "maximumPageSize": number, "name": "string", "nextPageToken": "string", "registrationStatus": "string", "reverseOrder": boolean } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain in which the workflow types have been registered. Type: String ListWorkflowTypes API Version 2012-01-25 116 Amazon Simple Workflow Service API Reference Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes maximumPageSize The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. Type: Integer Valid Range: Minimum value of 0. Maximum value of 1000. Required: No name If specified, lists the workflow type with this name. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again
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Simple Workflow Service API Reference Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes maximumPageSize The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. Type: Integer Valid Range: Minimum value of 0. Maximum value of 1000. Required: No name If specified, lists the workflow type with this name. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next page. Keep all other arguments unchanged. Each pagination token expires after 24 hours. Using an expired pagination token will return a 400 error: "Specified token has exceeded its maximum lifetime". The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. Required: No registrationStatus Specifies the registration status of the workflow types to list. Type: String Request Parameters API Version 2012-01-25 117 Amazon Simple Workflow Service API Reference Valid Values: REGISTERED | DEPRECATED Required: Yes reverseOrder When set to true, returns the results in reverse order. By default the results are returned in ascending alphabetical order of the name of the workflow types. Type: Boolean Required: No Response Syntax { "nextPageToken": "string", "typeInfos": [ { "creationDate": number, "deprecationDate": number, "description": "string", "status": "string", "workflowType": { "name": "string", "version": "string" } } ] } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. nextPageToken If a NextPageToken was returned by a previous call, there are more results available. To retrieve the next page of results, make the call again using the returned token in nextPageToken. Keep all other arguments unchanged. Response Syntax API Version 2012-01-25 118 Amazon Simple Workflow Service API Reference The configured maximumPageSize determines how many results can be returned in a single call. Type: String Length Constraints: Maximum length of 2048. typeInfos The list of workflow type information. Type: Array of WorkflowTypeInfo objects Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples ListWorkflowTypes Example This example illustrates one usage of ListWorkflowTypes. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Errors API Version 2012-01-25 119 Amazon Simple Workflow Service API Reference Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 22:25:43 GMT X-Amz-Target: SimpleWorkflowService.ListWorkflowTypes Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content-Encoding,Signature=uleWQSyVVf0+aG50IoBJG5h0hzxNFNT97Mkn/FSCQ +Q= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 110 Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "registrationStatus": "REGISTERED", "maximumPageSize": 50, "reverseOrder": true} Sample Response HTTP/1.1 200 OK Content-Length: 174 Content-Type: application/json x-amzn-RequestId: dcde6719-3fc7-11e1-9e8f-57bb03e21482 {"typeInfos": [ {"creationDate": 1326481174.027, "description": "Handle customer orders", "status": "REGISTERED", "workflowType": {"name": "customerOrderWorkflow", "version": "1.0"} } ] } Examples API Version 2012-01-25 120 Amazon Simple Workflow Service See Also API Reference For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 121 Amazon Simple Workflow Service PollForActivityTask API Reference Used by workers to get an ActivityTask from the specified activity taskList. This initiates a long poll, where the service holds the HTTP connection open and responds as soon as a task becomes available. The maximum time the service holds on to the request before responding is 60 seconds. If no task is available within 60 seconds, the poll returns an empty result. An empty result, in this context, means that an ActivityTask is returned, but that the value of taskToken is an empty string. If a task is returned, the worker should use its type to identify and process it correctly. Important Workers should set their client side socket timeout to at least 70 seconds (10 seconds higher than the maximum time service may hold the poll request). Access Control You can use IAM policies to control this action's access to Amazon SWF resources
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responding is 60 seconds. If no task is available within 60 seconds, the poll returns an empty result. An empty result, in this context, means that an ActivityTask is returned, but that the value of taskToken is an empty string. If a task is returned, the worker should use its type to identify and process it correctly. Important Workers should set their client side socket timeout to at least 70 seconds (10 seconds higher than the maximum time service may hold the poll request). Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the taskList.name parameter by using a Condition element with the swf:taskList.name key to allow the action to access only certain task lists. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "identity": "string", "taskList": { "name": "string" } PollForActivityTask API Version 2012-01-25 122 Amazon Simple Workflow Service } Request Parameters API Reference For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain that contains the task lists being polled. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes identity Identity of the worker making the request, recorded in the ActivityTaskStarted event in the workflow history. This enables diagnostic tracing when problems arise. The form of this identity is user defined. Type: String Length Constraints: Maximum length of 256. Required: No taskList Specifies the task list to poll for activity tasks. The specified string must not start or end with whitespace. It must not contain a : (colon), / (slash), | (vertical bar), or any control characters (\u0000-\u001f | \u007f-\u009f). Also, it must not be the literal string arn. Type: TaskList object Required: Yes Request Parameters API Version 2012-01-25 123 API Reference Amazon Simple Workflow Service Response Syntax { "activityId": "string", "activityType": { "name": "string", "version": "string" }, "input": "string", "startedEventId": number, "taskToken": "string", "workflowExecution": { "runId": "string", "workflowId": "string" } } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. activityId The unique ID of the task. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. activityType The type of this activity task. Type: ActivityType object input The inputs provided when the activity task was scheduled. The form of the input is user defined and should be meaningful to the activity implementation. Type: String Response Syntax API Version 2012-01-25 124 Amazon Simple Workflow Service API Reference Length Constraints: Maximum length of 32768. startedEventId The ID of the ActivityTaskStarted event recorded in the history. Type: Long taskToken The opaque string used as a handle on the task. This token is used by workers to communicate progress and response information back to the system about the task. Type: String Length Constraints: Minimum length of 1. Maximum length of 1024. workflowExecution The workflow execution that started this activity task. Type: WorkflowExecution object Errors For information about the errors that are common to all actions, see Common Errors. LimitExceededFault Returned by any operation if a system imposed limitation has been reached. To address this fault you should either clean up unused resources or increase the limit by contacting AWS. HTTP Status Code: 400 OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. Errors API Version 2012-01-25 125 API Reference Amazon Simple Workflow Service HTTP Status Code: 400 Examples PollForActivityTask Example This example illustrates one usage of PollForActivityTask. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Mon, 16 Jan 2012 03:53:52 GMT X-Amz-Target: SimpleWorkflowService.PollForActivityTask Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content-Encoding,Signature=dv0H1RPYucoIcRckspWO0f8xG120MWZRKmj3O5/ A4rY= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 108 Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "taskList": {"name": "mainTaskList"}, "identity": "VerifyCreditCardWorker01"} Sample Response HTTP/1.1 200 OK Examples API Version 2012-01-25 126
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Amazon Simple Workflow Service HTTP Status Code: 400 Examples PollForActivityTask Example This example illustrates one usage of PollForActivityTask. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Mon, 16 Jan 2012 03:53:52 GMT X-Amz-Target: SimpleWorkflowService.PollForActivityTask Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content-Encoding,Signature=dv0H1RPYucoIcRckspWO0f8xG120MWZRKmj3O5/ A4rY= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 108 Pragma: no-cache Cache-Control: no-cache {"domain": "867530901", "taskList": {"name": "mainTaskList"}, "identity": "VerifyCreditCardWorker01"} Sample Response HTTP/1.1 200 OK Examples API Version 2012-01-25 126 Amazon Simple Workflow Service Content-Length: 837 Content-Type: application/json x-amzn-RequestId: b48fb6b5-3ff5-11e1-a23a-99d60383ae71 API Reference {"activityId": "verification-27", "activityType": {"name": "activityVerify", "version": "1.0"}, "input": "5634-0056-4367-0923,12/12,437", "startedEventId": 11, "taskToken": "AAAAKgAAAAEAAAAAAAAAAX9p3pcp3857oLXFUuwdxRU5/ zmn9f40XaMF7VohAH4jOtjXpZu7GdOzEi0b3cWYHbG5b5dpdcTXHUDPVMHXiUxCgr+Nc/wUW9016W4YxJGs/ jmxzPln8qLftU+SW135Q0UuKp5XRGoRTJp3tbHn2pY1vC8gDB/K69J6q668U1pd4Cd9o43// lGgOIjN0/Ihg+DO+83HNcOuVEQMM28kNMXf7yePh31M4dMKJwQaQZG13huJXDwzJOoZQz+XFuqFly +lPnCE4XvsnhfAvTsh50EtNDEtQzPCFJoUeld9g64V/FS/39PHL3M93PBUuroPyHuCwHsNC6fZ7gM/ XOKmW4kKnXPoQweEUkFV/J6E6+M1reBO7nJADTrLSnajg6MY/viWsEYmMw/ DS5FlquFaDIhFkLhWUWN+V2KqiKS23GYwpzgZ7fgcWHQF2NLEY3zrjam4LW/ UW5VLCyM3FpVD3erCTi9IvUgslPzyVGuWNAoTmgJEWvimgwiHxJMxxc9JBDR390iMmImxVl3eeSDUWx8reQltiviadPDjyRmVhYP8", "workflowExecution": {"runId": "cfa2bd33-31b0-4b75-b131-255bb0d97b3f", "workflowId": "20110927-T-1"} } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 127 Amazon Simple Workflow Service API Reference See Also API Version 2012-01-25 128 Amazon Simple Workflow Service API Reference PollForDecisionTask Used by deciders to get a DecisionTask from the specified decision taskList. A decision task may be returned for any open workflow execution that is using the specified task list. The task includes a paginated view of the history of the workflow execution. The decider should use the workflow type and the history to determine how to properly handle the task. This action initiates a long poll, where the service holds the HTTP connection open and responds as soon a task becomes available. If no decision task is available in the specified task list before the timeout of 60 seconds expires, an empty result is returned. An empty result, in this context, means that a DecisionTask is returned, but that the value of taskToken is an empty string. Important Deciders should set their client side socket timeout to at least 70 seconds (10 seconds higher than the timeout). Important Because the number of workflow history events for a single workflow execution might be very large, the result returned might be split up across a number of pages. To retrieve subsequent pages, make additional calls to PollForDecisionTask using the nextPageToken returned by the initial call. Note that you do not call GetWorkflowExecutionHistory with this nextPageToken. Instead, call PollForDecisionTask again. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the taskList.name parameter by using a Condition element with the swf:taskList.name key to allow the action to access only certain task lists. PollForDecisionTask API Version 2012-01-25 129 Amazon Simple Workflow Service API Reference If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "domain": "string", "identity": "string", "maximumPageSize": number, "nextPageToken": "string", "reverseOrder": boolean, "startAtPreviousStartedEvent": boolean, "taskList": { "name": "string" } } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. domain The name of the domain containing the task lists to poll. Type: String Length Constraints: Minimum length of 1. Maximum length of 256. Required: Yes identity Identity of the decider making the request, which is recorded in the DecisionTaskStarted event in the workflow history. This enables diagnostic tracing when problems arise. The form of this identity is user defined. Type: String Request Syntax API Version 2012-01-25 130 Amazon Simple Workflow Service API Reference Length Constraints: Maximum length of 256. Required: No maximumPageSize The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. This is an upper limit only; the actual number of results returned per call may be fewer than the specified maximum. Type: Integer Valid Range: Minimum value of 0. Maximum value of 1000. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next
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Workflow Service API Reference Length Constraints: Maximum length of 256. Required: No maximumPageSize The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results. This is an upper limit only; the actual number of results returned per call may be fewer than the specified maximum. Type: Integer Valid Range: Minimum value of 0. Maximum value of 1000. Required: No nextPageToken If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next page. Keep all other arguments unchanged. Each pagination token expires after 24 hours. Using an expired pagination token will return a 400 error: "Specified token has exceeded its maximum lifetime". The configured maximumPageSize determines how many results can be returned in a single call. Note The nextPageToken returned by this action cannot be used with GetWorkflowExecutionHistory to get the next page. You must call PollForDecisionTask again (with the nextPageToken) to retrieve the next page of history records. Calling PollForDecisionTask with a nextPageToken doesn't return a new decision task. Type: String Length Constraints: Maximum length of 2048. Required: No Request Parameters API Version 2012-01-25 131 Amazon Simple Workflow Service reverseOrder API Reference When set to true, returns the events in reverse order. By default the results are returned in ascending order of the eventTimestamp of the events. Type: Boolean Required: No startAtPreviousStartedEvent When set to true, returns the events with eventTimestamp greater than or equal to eventTimestamp of the most recent DecisionTaskStarted event. By default, this parameter is set to false. Type: Boolean Required: No taskList Specifies the task list to poll for decision tasks. The specified string must not contain a : (colon), / (slash), | (vertical bar), or any control characters (\u0000-\u001f | \u007f-\u009f). Also, it must not be the literal string arn. Type: TaskList object Required: Yes Response Syntax { "events": [ { "activityTaskCanceledEventAttributes": { "details": "string", "latestCancelRequestedEventId": number, "scheduledEventId": number, "startedEventId": number }, "activityTaskCancelRequestedEventAttributes": { "activityId": "string", "decisionTaskCompletedEventId": number Response Syntax API Version 2012-01-25 132 API Reference Amazon Simple Workflow Service }, "activityTaskCompletedEventAttributes": { "result": "string", "scheduledEventId": number, "startedEventId": number }, "activityTaskFailedEventAttributes": { "details": "string", "reason": "string", "scheduledEventId": number, "startedEventId": number }, "activityTaskScheduledEventAttributes": { "activityId": "string", "activityType": { "name": "string", "version": "string" }, "control": "string", "decisionTaskCompletedEventId": number, "heartbeatTimeout": "string", "input": "string", "scheduleToCloseTimeout": "string", "scheduleToStartTimeout": "string", "startToCloseTimeout": "string", "taskList": { "name": "string" }, "taskPriority": "string" }, "activityTaskStartedEventAttributes": { "identity": "string", "scheduledEventId": number }, "activityTaskTimedOutEventAttributes": { "details": "string", "scheduledEventId": number, "startedEventId": number, "timeoutType": "string" }, "cancelTimerFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number, "timerId": "string" Response Syntax API Version 2012-01-25 133 API Reference Amazon Simple Workflow Service }, "cancelWorkflowExecutionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number }, "childWorkflowExecutionCanceledEventAttributes": { "details": "string", "initiatedEventId": number, "startedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "childWorkflowExecutionCompletedEventAttributes": { "initiatedEventId": number, "result": "string", "startedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "childWorkflowExecutionFailedEventAttributes": { "details": "string", "initiatedEventId": number, "reason": "string", "startedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } Response Syntax API Version 2012-01-25 134 API Reference Amazon Simple Workflow Service }, "childWorkflowExecutionStartedEventAttributes": { "initiatedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "childWorkflowExecutionTerminatedEventAttributes": { "initiatedEventId": number, "startedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "childWorkflowExecutionTimedOutEventAttributes": { "initiatedEventId": number, "startedEventId": number, "timeoutType": "string", "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } }, "completeWorkflowExecutionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number }, "continueAsNewWorkflowExecutionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number Response Syntax API Version 2012-01-25 135 API Reference Amazon Simple Workflow Service }, "decisionTaskCompletedEventAttributes": { "executionContext": "string", "scheduledEventId": number, "startedEventId": number, "taskList": { "name": "string" }, "taskListScheduleToStartTimeout": "string" }, "decisionTaskScheduledEventAttributes": { "scheduleToStartTimeout": "string", "startToCloseTimeout": "string", "taskList": { "name": "string" }, "taskPriority": "string" }, "decisionTaskStartedEventAttributes": { "identity": "string", "scheduledEventId": number }, "decisionTaskTimedOutEventAttributes": { "scheduledEventId": number, "startedEventId": number, "timeoutType": "string" }, "eventId": number, "eventTimestamp": number, "eventType": "string", "externalWorkflowExecutionCancelRequestedEventAttributes": { "initiatedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" } }, "externalWorkflowExecutionSignaledEventAttributes": { "initiatedEventId": number, "workflowExecution": { "runId": "string", "workflowId": "string" } }, Response Syntax API Version 2012-01-25 136 Amazon Simple Workflow Service API Reference "failWorkflowExecutionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number }, "lambdaFunctionCompletedEventAttributes": { "result": "string", "scheduledEventId": number, "startedEventId": number }, "lambdaFunctionFailedEventAttributes": { "details": "string", "reason": "string", "scheduledEventId": number, "startedEventId": number }, "lambdaFunctionScheduledEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "id": "string", "input": "string", "name": "string", "startToCloseTimeout": "string" }, "lambdaFunctionStartedEventAttributes": { "scheduledEventId": number }, "lambdaFunctionTimedOutEventAttributes": { "scheduledEventId": number, "startedEventId": number, "timeoutType": "string" }, "markerRecordedEventAttributes": { "decisionTaskCompletedEventId": number, "details": "string", "markerName": "string" }, "recordMarkerFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number, "markerName": "string" }, "requestCancelActivityTaskFailedEventAttributes": { "activityId": "string", "cause": "string", Response Syntax API Version 2012-01-25 137
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} }, Response Syntax API Version 2012-01-25 136 Amazon Simple Workflow Service API Reference "failWorkflowExecutionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number }, "lambdaFunctionCompletedEventAttributes": { "result": "string", "scheduledEventId": number, "startedEventId": number }, "lambdaFunctionFailedEventAttributes": { "details": "string", "reason": "string", "scheduledEventId": number, "startedEventId": number }, "lambdaFunctionScheduledEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "id": "string", "input": "string", "name": "string", "startToCloseTimeout": "string" }, "lambdaFunctionStartedEventAttributes": { "scheduledEventId": number }, "lambdaFunctionTimedOutEventAttributes": { "scheduledEventId": number, "startedEventId": number, "timeoutType": "string" }, "markerRecordedEventAttributes": { "decisionTaskCompletedEventId": number, "details": "string", "markerName": "string" }, "recordMarkerFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number, "markerName": "string" }, "requestCancelActivityTaskFailedEventAttributes": { "activityId": "string", "cause": "string", Response Syntax API Version 2012-01-25 137 Amazon Simple Workflow Service API Reference "decisionTaskCompletedEventId": number }, "requestCancelExternalWorkflowExecutionFailedEventAttributes": { "cause": "string", "control": "string", "decisionTaskCompletedEventId": number, "initiatedEventId": number, "runId": "string", "workflowId": "string" }, "requestCancelExternalWorkflowExecutionInitiatedEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "runId": "string", "workflowId": "string" }, "scheduleActivityTaskFailedEventAttributes": { "activityId": "string", "activityType": { "name": "string", "version": "string" }, "cause": "string", "decisionTaskCompletedEventId": number }, "scheduleLambdaFunctionFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number, "id": "string", "name": "string" }, "signalExternalWorkflowExecutionFailedEventAttributes": { "cause": "string", "control": "string", "decisionTaskCompletedEventId": number, "initiatedEventId": number, "runId": "string", "workflowId": "string" }, "signalExternalWorkflowExecutionInitiatedEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "input": "string", "runId": "string", Response Syntax API Version 2012-01-25 138 Amazon Simple Workflow Service API Reference "signalName": "string", "workflowId": "string" }, "startChildWorkflowExecutionFailedEventAttributes": { "cause": "string", "control": "string", "decisionTaskCompletedEventId": number, "initiatedEventId": number, "workflowId": "string", "workflowType": { "name": "string", "version": "string" } }, "startChildWorkflowExecutionInitiatedEventAttributes": { "childPolicy": "string", "control": "string", "decisionTaskCompletedEventId": number, "executionStartToCloseTimeout": "string", "input": "string", "lambdaRole": "string", "tagList": [ "string" ], "taskList": { "name": "string" }, "taskPriority": "string", "taskStartToCloseTimeout": "string", "workflowId": "string", "workflowType": { "name": "string", "version": "string" } }, "startLambdaFunctionFailedEventAttributes": { "cause": "string", "message": "string", "scheduledEventId": number }, "startTimerFailedEventAttributes": { "cause": "string", "decisionTaskCompletedEventId": number, "timerId": "string" }, "timerCanceledEventAttributes": { Response Syntax API Version 2012-01-25 139 Amazon Simple Workflow Service API Reference "decisionTaskCompletedEventId": number, "startedEventId": number, "timerId": "string" }, "timerFiredEventAttributes": { "startedEventId": number, "timerId": "string" }, "timerStartedEventAttributes": { "control": "string", "decisionTaskCompletedEventId": number, "startToFireTimeout": "string", "timerId": "string" }, "workflowExecutionCanceledEventAttributes": { "decisionTaskCompletedEventId": number, "details": "string" }, "workflowExecutionCancelRequestedEventAttributes": { "cause": "string", "externalInitiatedEventId": number, "externalWorkflowExecution": { "runId": "string", "workflowId": "string" } }, "workflowExecutionCompletedEventAttributes": { "decisionTaskCompletedEventId": number, "result": "string" }, "workflowExecutionContinuedAsNewEventAttributes": { "childPolicy": "string", "decisionTaskCompletedEventId": number, "executionStartToCloseTimeout": "string", "input": "string", "lambdaRole": "string", "newExecutionRunId": "string", "tagList": [ "string" ], "taskList": { "name": "string" }, "taskPriority": "string", "taskStartToCloseTimeout": "string", "workflowType": { Response Syntax API Version 2012-01-25 140 Amazon Simple Workflow Service API Reference "name": "string", "version": "string" } }, "workflowExecutionFailedEventAttributes": { "decisionTaskCompletedEventId": number, "details": "string", "reason": "string" }, "workflowExecutionSignaledEventAttributes": { "externalInitiatedEventId": number, "externalWorkflowExecution": { "runId": "string", "workflowId": "string" }, "input": "string", "signalName": "string" }, "workflowExecutionStartedEventAttributes": { "childPolicy": "string", "continuedExecutionRunId": "string", "executionStartToCloseTimeout": "string", "input": "string", "lambdaRole": "string", "parentInitiatedEventId": number, "parentWorkflowExecution": { "runId": "string", "workflowId": "string" }, "tagList": [ "string" ], "taskList": { "name": "string" }, "taskPriority": "string", "taskStartToCloseTimeout": "string", "workflowType": { "name": "string", "version": "string" } }, "workflowExecutionTerminatedEventAttributes": { "cause": "string", "childPolicy": "string", "details": "string", Response Syntax API Version 2012-01-25 141 Amazon Simple Workflow Service API Reference "reason": "string" }, "workflowExecutionTimedOutEventAttributes": { "childPolicy": "string", "timeoutType": "string" } } ], "nextPageToken": "string", "previousStartedEventId": number, "startedEventId": number, "taskToken": "string", "workflowExecution": { "runId": "string", "workflowId": "string" }, "workflowType": { "name": "string", "version": "string" } } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. events A paginated list of history events of the workflow execution. The decider uses this during the processing of the decision task. Type: Array of HistoryEvent objects nextPageToken If a NextPageToken was returned by a previous call, there are more results available. To retrieve the next page of results, make the call again using the returned token in nextPageToken. Keep all other arguments unchanged. The configured maximumPageSize determines how many results can be returned in a single call. Response Elements API Version 2012-01-25 142 Amazon Simple Workflow Service Type: String Length Constraints: Maximum length of 2048. previousStartedEventId API Reference The ID of the DecisionTaskStarted event of the previous decision task of this workflow execution that was processed by the decider. This can be used to determine the events in the history new since the last decision task received by the decider. Type: Long startedEventId The ID of the DecisionTaskStarted event recorded in the history. Type: Long taskToken The opaque string used as a handle on the task. This token is used by workers to communicate progress and response information back to the system about the task. Type: String Length Constraints: Minimum length of 1. Maximum length of 1024. workflowExecution The workflow execution for which this decision task was created. Type: WorkflowExecution object workflowType The type of the workflow execution for which this decision task was created. Type: WorkflowType object Errors For information about the errors that are common to all actions, see Common Errors. LimitExceededFault Returned by any operation if a system imposed limitation has been reached. To address
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string used as a handle on the task. This token is used by workers to communicate progress and response information back to the system about the task. Type: String Length Constraints: Minimum length of 1. Maximum length of 1024. workflowExecution The workflow execution for which this decision task was created. Type: WorkflowExecution object workflowType The type of the workflow execution for which this decision task was created. Type: WorkflowType object Errors For information about the errors that are common to all actions, see Common Errors. LimitExceededFault Returned by any operation if a system imposed limitation has been reached. To address this fault you should either clean up unused resources or increase the limit by contacting AWS. Errors API Version 2012-01-25 143 Amazon Simple Workflow Service HTTP Status Code: 400 OperationNotPermittedFault API Reference Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 UnknownResourceFault Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples PollForDecisionTask Example This example illustrates one usage of PollForDecisionTask. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Sun, 15 Jan 2012 02:09:54 GMT X-Amz-Target: SimpleWorkflowService.PollForDecisionTask Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X- Amz-Date;X-Amz-Target;Content-Encoding,Signature=R3CJ2HMLSVpc2p6eafeztZCZWcgza +h61gSUuWx15gw= Examples API Version 2012-01-25 144 Amazon Simple Workflow Service API Reference Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 171 Pragma: no-cache Cache-Control: no-cache { "maximumPageSize": 50, "domain": "867530901", "taskList": { "name": "specialTaskList" }, "reverseOrder": true, "identity": "Decider01" } Sample Response HTTP/1.1 200 OK Content-Length: 1639 Content-Type: application/json x-amzn-RequestId: 03db54cf-3f1e-11e1-b118-3bfa5e8e7fc3 { "previousStartedEventId": 0, "workflowExecution": { "workflowId": "20110927-T-1", "runId": "06b8f87a-24b3-40b6-9ceb-9676f28e9493" }, "startedEventId": 3, "workflowType": { "version": "1.0", "name": "customerOrderWorkflow" }, "events": [ { "eventId": 3, "decisionTaskStartedEventAttributes": { "scheduledEventId": 2, "identity": "Decider01" }, "eventTimestamp": 1326593394.566, "eventType": "DecisionTaskStarted" }, Examples API Version 2012-01-25 145 API Reference Amazon Simple Workflow Service { "eventId": 2, "eventType": "DecisionTaskScheduled", "decisionTaskScheduledEventAttributes": { "startToCloseTimeout": "600", "taskList": { "name": "specialTaskList" }, "taskPriority": "100" }, "eventTimestamp": 1326592619.474 }, { "eventId": 1, "eventType": "WorkflowExecutionStarted", "workflowExecutionStartedEventAttributes": { "taskList": { "name": "specialTaskList" }, "parentInitiatedEventId": 0, "taskStartToCloseTimeout": "600", "childPolicy": "TERMINATE", "executionStartToCloseTimeout": "3600", "input": "arbitrary-string-that-is-meaningful-to-the-workflow", "workflowType": { "version": "1.0", "name": "customerOrderWorkflow" }, "tagList": [ "music purchase", "digital", "ricoh-the-dog" ] }, "eventTimestamp": 1326592619.474 } ], "taskToken": "AAAAKgAAAAEAAAAAAAAAATZDvCYwk/hP/X1ZGdJhb +T6OWzcBx2DPhsIi5HF4aGQI4OXrDE7Ny3uM+aiAhGrmeNyVAa4yNIBQuoZuJA5G +BoaB0JuHFBOynHDTnm7ayNH43KhMkfdrDG4elfHSz3m/ EtbLnFGueAr7+3NKDG6x4sTKg3cZpOtSguSx05yI1X3AtscS8ATcLB2Y3Aub1YonN/ i/k67voca/GFsSiwSz3AAnJj1IPvrujgIj9KUvckwRPC5ET7d33XJcRp +gHYzZsBLVBaRmV3gEYAnp2ICslFn4YSjGy+dFXCNpOa4G1O8pczCbFUGbQ3+5wf0RSaa/ xMq2pfdBKnuFp0wp8kw1k+5ZsbtDZeZn8g5GyKCLiLms/xD0OxugGGUe5ZlAoHEkTWGxZj/ Examples API Version 2012-01-25 146 Amazon Simple Workflow Service API Reference G32P7cMoCgrcACfFPdx1LNYYEre7YiGiyjGnfW2t5mW7VK9Np28vcXVbdpH4JNEB9OuB1xqL8N8ifPVtc72uxB1i9XEdq/8rkXasSEw4TubB2FwgqnuJstmfEhpOdb5HfhR6OwmnHuk9eszO/ fUkGucTUXQP2hhB+Gz" } See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 147 Amazon Simple Workflow Service API Reference RecordActivityTaskHeartbeat Used by activity workers to report to the service that the ActivityTask represented by the specified taskToken is still making progress. The worker can also specify details of the progress, for example percent complete, using the details parameter. This action can also be used by the worker as a mechanism to check if cancellation is being requested for the activity task. If a cancellation is being attempted for the specified task, then the boolean cancelRequested flag returned by the service is set to true. This action resets the taskHeartbeatTimeout clock. The taskHeartbeatTimeout is specified in RegisterActivityType. This action doesn't in itself create an event in the workflow execution history. However, if the task times out, the workflow execution history contains a ActivityTaskTimedOut event that contains the information from the last heartbeat generated by the activity worker. Note The taskStartToCloseTimeout of an activity type is the maximum duration of an activity task, regardless of the number of RecordActivityTaskHeartbeat requests received. The taskStartToCloseTimeout is also specified in RegisterActivityType. Note This operation is only useful for long-lived activities to report liveliness of the task and to determine if a cancellation is being attempted. Important If the cancelRequested flag returns true, a cancellation is being attempted. If the worker can cancel the activity, it should respond with RespondActivityTaskCanceled. Otherwise, it should ignore the cancellation request. Access Control RecordActivityTaskHeartbeat API Version 2012-01-25 148 Amazon Simple Workflow Service API Reference You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. •
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to determine if a cancellation is being attempted. Important If the cancelRequested flag returns true, a cancellation is being attempted. If the worker can cancel the activity, it should respond with RespondActivityTaskCanceled. Otherwise, it should ignore the cancellation request. Access Control RecordActivityTaskHeartbeat API Version 2012-01-25 148 Amazon Simple Workflow Service API Reference You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • You cannot use an IAM policy to constrain this action's parameters. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide. Request Syntax { "details": "string", "taskToken": "string" } Request Parameters For information about the parameters that are common to all actions, see Common Parameters. The request accepts the following data in JSON format. details If specified, contains details about the progress of the task. Type: String Length Constraints: Maximum length of 2048. Required: No taskToken The taskToken of the ActivityTask. Request Syntax API Version 2012-01-25 149 Amazon Simple Workflow Service API Reference Important taskToken is generated by the service and should be treated as an opaque value. If the task is passed to another process, its taskToken must also be passed. This enables it to provide its progress and respond with results. Type: String Length Constraints: Minimum length of 1. Maximum length of 1024. Required: Yes Response Syntax { "cancelRequested": boolean } Response Elements If the action is successful, the service sends back an HTTP 200 response. The following data is returned in JSON format by the service. cancelRequested Set to true if cancellation of the task is requested. Type: Boolean Errors For information about the errors that are common to all actions, see Common Errors. OperationNotPermittedFault Returned when the caller doesn't have sufficient permissions to invoke the action. HTTP Status Code: 400 Response Syntax API Version 2012-01-25 150 Amazon Simple Workflow Service UnknownResourceFault API Reference Returned when the named resource cannot be found with in the scope of this operation (region or domain). This could happen if the named resource was never created or is no longer available for this operation. HTTP Status Code: 400 Examples RecordActivityTaskHeartbeat Example This example illustrates one usage of RecordActivityTaskHeartbeat. Sample Request POST / HTTP/1.1 Host: swf.us-east-1.amazonaws.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.25) Gecko/20111212 Firefox/3.6.25 ( .NET CLR 3.5.30729; .NET4.0E) Accept: application/json, text/javascript, */* Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 115 Connection: keep-alive Content-Type: application/x-amz-json-1.0 X-Requested-With: XMLHttpRequest X-Amz-Date: Mon, 16 Jan 2012 03:55:06 GMT X-Amz-Target: SimpleWorkflowService.RecordActivityTaskHeartbeat Content-Encoding: amz-1.0 X-Amzn-Authorization: AWS3 AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE,Algorithm=HmacSHA256,SignedHeaders=Host;X-Amz- Date;X-Amz-Target;Content- Encoding,Signature=DEA8rw5TqtpqCeTljl7eotZkuWTgmGZ1PWyDNZPehT0= Referer: http://swf.us-east-1.amazonaws.com/explorer/index.html Content-Length: 623 Pragma: no-cache Cache-Control: no-cache {"taskToken": "AAAAKgAAAAEAAAAAAAAAAX9p3pcp3857oLXFUuwdxRU5/ zmn9f40XaMF7VohAH4jOtjXpZu7GdOzEi0b3cWYHbG5b5dpdcTXHUDPVMHXiUxCgr+Nc/wUW9016W4YxJGs/ Examples API Version 2012-01-25 151 Amazon Simple Workflow Service API Reference jmxzPln8qLftU+SW135Q0UuKp5XRGoRTJp3tbHn2pY1vC8gDB/K69J6q668U1pd4Cd9o43// lGgOIjN0/Ihg+DO+83HNcOuVEQMM28kNMXf7yePh31M4dMKJwQaQZG13huJXDwzJOoZQz+XFuqFly +lPnCE4XvsnhfAvTsh50EtNDEtQzPCFJoUeld9g64V/FS/39PHL3M93PBUuroPyHuCwHsNC6fZ7gM/ XOKmW4kKnXPoQweEUkFV/J6E6+M1reBO7nJADTrLSnajg6MY/viWsEYmMw/ DS5FlquFaDIhFkLhWUWN+V2KqiKS23GYwpzgZ7fgcWHQF2NLEY3zrjam4LW/ UW5VLCyM3FpVD3erCTi9IvUgslPzyVGuWNAoTmgJEWvimgwiHxJMxxc9JBDR390iMmImxVl3eeSDUWx8reQltiviadPDjyRmVhYP8", "details": "starting task"} Sample Response HTTP/1.1 200 OK Content-Length: 25 Content-Type: application/json x-amzn-RequestId: e08622cd-3ff5-11e1-9b11-7182192d0b57 {"cancelRequested":false} See Also For more information about using this API in one of the language-specific AWS SDKs, see the following: • AWS Command Line Interface • AWS SDK for .NET • AWS SDK for C++ • AWS SDK for Go v2 • AWS SDK for Java V2 • AWS SDK for JavaScript V3 • AWS SDK for Kotlin • AWS SDK for PHP V3 • AWS SDK for Python • AWS SDK for Ruby V3 See Also API Version 2012-01-25 152 Amazon Simple Workflow Service API Reference RegisterActivityType Registers a new activity type along with its configuration settings in the specified domain. Important A TypeAlreadyExists fault is returned if the type already exists in the domain. You cannot change any configuration settings of the type after its registration, and it must be registered as a new version. Access Control You can use IAM policies to control this action's access to Amazon SWF resources as follows: • Use a Resource element with the domain name to limit the action to only specified domains. • Use an Action element to allow or deny permission to call this action. • Constrain the following parameters by using a Condition element with the appropriate keys. • defaultTaskList.name: String constraint. The key is swf:defaultTaskList.name. • name: String constraint. The key is swf:name. • version: String constraint. The key is swf:version. If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access
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