Chapter 121. Stub
Chapter 121. Stub Both producer and consumer are supported The Stub component provides a simple way to stub out any physical endpoints while in development or testing, allowing you for example to run a route without needing to actually connect to a specific specific SMTP or HTTP endpoint. Just add stub: in front of any endpoint URI to stub out the endpoint. Internally the Stub component creates VM endpoints. The main difference between Stub and VM is that VM will validate the URI and parameters you give it, so putting vm: in front of a typical URI with query arguments will usually fail. Stub won't though, as it basically ignores all query parameters to let you quickly stub out one or more endpoints in your route temporarily. 121.1. Dependencies When using stub with Red Hat build of Camel Spring Boot make sure to use the following Maven dependency to have support for auto configuration: <dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-stub-starter</artifactId> </dependency> 121.2. URI format Where someUri can be any URI with any query parameters. 121.3. Configuring Options Camel components are configured on two levels: Component level Endpoint level 121.3.1. Component Level Options The component level is the highest level. The configurations you define at this level are inherited by all the endpoints. For example, a component can have security settings, credentials for authentication, urls for network connection, and so on. Since components typically have pre-configured defaults for the most common cases, you may need to only configure a few component options, or maybe none at all. You can configure components with Component DSL in a configuration file (application.properties|yaml), or directly with Java code. 121.3.2. Endpoint Level Options At the Endpoint level you have many options, which you can use to configure what you want the endpoint to do. The options are categorized according to whether the endpoint is used as a consumer (from) or as a producer (to) or used for both. You can configure endpoints directly in the endpoint URI as path and query parameters. You can also use Endpoint DSL and DataFormat DSL as type safe ways of configuring endpoints and data formats in Java. When configuring options, use Property Placeholders for urls, port numbers, sensitive information, and other settings. Placeholders allows you to externalize the configuration from your code, giving you more flexible and reusable code. 121.4. Component Options The Stub component supports 10 options, which are listed below. Name Description Default Type bridgeErrorHandler (consumer) Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. false boolean concurrentConsumers (consumer) Sets the default number of concurrent threads processing exchanges. 1 int defaultPollTimeout (consumer (advanced)) The timeout (in milliseconds) used when polling. When a timeout occurs, the consumer can check whether it is allowed to continue running. Setting a lower value allows the consumer to react more quickly upon shutdown. 1000 int defaultBlockWhenFull (producer) Whether a thread that sends messages to a full SEDA queue will block until the queue's capacity is no longer exhausted. By default, an exception will be thrown stating that the queue is full. By enabling this option, the calling thread will instead block and wait until the message can be accepted. false boolean defaultDiscardWhenFull (producer) Whether a thread that sends messages to a full SEDA queue will be discarded. By default, an exception will be thrown stating that the queue is full. By enabling this option, the calling thread will give up sending and continue, meaning that the message was not sent to the SEDA queue. false boolean defaultOfferTimeout (producer) Whether a thread that sends messages to a full SEDA queue will block until the queue's capacity is no longer exhausted. By default, an exception will be thrown stating that the queue is full. By enabling this option, where a configured timeout can be added to the block case. Utilizing the .offer(timeout) method of the underlining java queue. long lazyStartProducer (producer) Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. false boolean autowiredEnabled (advanced) Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. true boolean defaultQueueFactory (advanced) Sets the default queue factory. BlockingQueueFactory queueSize (advanced) Sets the default maximum capacity of the SEDA queue (i.e., the number of messages it can hold). 1000 int 121.5. Endpoint Options The Stub endpoint is configured using URI syntax: with the following path and query parameters: 121.5.1. Path Parameters (1 parameters) Name Description Default Type name (common) Required Name of queue. String 121.5.2. Query Parameters (18 parameters) Name Description Default Type size (common) The maximum capacity of the SEDA queue (i.e., the number of messages it can hold). Will by default use the defaultSize set on the SEDA component. 1000 int bridgeErrorHandler (consumer) Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. false boolean concurrentConsumers (consumer) Number of concurrent threads processing exchanges. 1 int exceptionHandler (consumer (advanced)) To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored. ExceptionHandler exchangePattern (consumer (advanced)) Sets the exchange pattern when the consumer creates an exchange. Enum values: InOnly InOut InOptionalOut ExchangePattern limitConcurrentConsumers (consumer (advanced)) Whether to limit the number of concurrentConsumers to the maximum of 500. By default, an exception will be thrown if an endpoint is configured with a greater number. You can disable that check by turning this option off. true boolean multipleConsumers (consumer (advanced)) Specifies whether multiple consumers are allowed. If enabled, you can use SEDA for Publish-Subscribe messaging. That is, you can send a message to the SEDA queue and have each consumer receive a copy of the message. When enabled, this option should be specified on every consumer endpoint. false boolean pollTimeout (consumer (advanced)) The timeout (in milliseconds) used when polling. When a timeout occurs, the consumer can check whether it is allowed to continue running. Setting a lower value allows the consumer to react more quickly upon shutdown. 1000 int purgeWhenStopping (consumer (advanced)) Whether to purge the task queue when stopping the consumer/route. This allows to stop faster, as any pending messages on the queue is discarded. false boolean blockWhenFull (producer) Whether a thread that sends messages to a full SEDA queue will block until the queue's capacity is no longer exhausted. By default, an exception will be thrown stating that the queue is full. By enabling this option, the calling thread will instead block and wait until the message can be accepted. false boolean discardIfNoConsumers (producer) Whether the producer should discard the message (do not add the message to the queue), when sending to a queue with no active consumers. Only one of the options discardIfNoConsumers and failIfNoConsumers can be enabled at the same time. false boolean discardWhenFull (producer) Whether a thread that sends messages to a full SEDA queue will be discarded. By default, an exception will be thrown stating that the queue is full. By enabling this option, the calling thread will give up sending and continue, meaning that the message was not sent to the SEDA queue. false boolean failIfNoConsumers (producer) Whether the producer should fail by throwing an exception, when sending to a queue with no active consumers. Only one of the options discardIfNoConsumers and failIfNoConsumers can be enabled at the same time. false boolean lazyStartProducer (producer) Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. false boolean offerTimeout (producer) Offer timeout (in milliseconds) can be added to the block case when queue is full. You can disable timeout by using 0 or a negative value. long timeout (producer) Timeout (in milliseconds) before a SEDA producer will stop waiting for an asynchronous task to complete. You can disable timeout by using 0 or a negative value. 30000 long waitForTaskToComplete (producer) Option to specify whether the caller should wait for the async task to complete or not before continuing. The following three options are supported: Always, Never or IfReplyExpected. The first two values are self-explanatory. The last value, IfReplyExpected, will only wait if the message is Request Reply based. The default option is IfReplyExpected. Enum values: Never IfReplyExpected Always IfReplyExpected WaitForTaskToComplete queue (advanced) Define the queue instance which will be used by the endpoint. BlockingQueue 121.6. Examples Here are a few samples of stubbing endpoint uris 121.7. Spring Boot Auto-Configuration The component supports 11 options, which are listed below. Name Description Default Type camel.component.stub.autowired-enabled Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. true Boolean camel.component.stub.bridge-error-handler Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. false Boolean camel.component.stub.concurrent-consumers Sets the default number of concurrent threads processing exchanges. 1 Integer camel.component.stub.default-block-when-full Whether a thread that sends messages to a full SEDA queue will block until the queue's capacity is no longer exhausted. By default, an exception will be thrown stating that the queue is full. By enabling this option, the calling thread will instead block and wait until the message can be accepted. false Boolean camel.component.stub.default-discard-when-full Whether a thread that sends messages to a full SEDA queue will be discarded. By default, an exception will be thrown stating that the queue is full. By enabling this option, the calling thread will give up sending and continue, meaning that the message was not sent to the SEDA queue. false Boolean camel.component.stub.default-offer-timeout Whether a thread that sends messages to a full SEDA queue will block until the queue's capacity is no longer exhausted. By default, an exception will be thrown stating that the queue is full. By enabling this option, where a configured timeout can be added to the block case. Utilizing the .offer(timeout) method of the underlining java queue. Long camel.component.stub.default-poll-timeout The timeout (in milliseconds) used when polling. When a timeout occurs, the consumer can check whether it is allowed to continue running. Setting a lower value allows the consumer to react more quickly upon shutdown. 1000 Integer camel.component.stub.default-queue-factory Sets the default queue factory. The option is a org.apache.camel.component.seda.BlockingQueueFactory<org.apache.camel.Exchange> type. BlockingQueueFactory camel.component.stub.enabled Whether to enable auto configuration of the stub component. This is enabled by default. Boolean camel.component.stub.lazy-start-producer Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. false Boolean camel.component.stub.queue-size Sets the default maximum capacity of the SEDA queue (i.e., the number of messages it can hold). 1000 Integer
<dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-stub-starter</artifactId> </dependency> stub:someUri stub:name stub:smtp://somehost.foo.com?user=whatnot&something=else stub:http://somehost.bar.com/something