FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to a method of delivering an instruction to a mobile user device connected to a network. 
       BACKGROUND 
       [0002]    Amongst the wide variety of portable electronic devices available today, mobile phones have become particularly pervasive, with more than double the penetration of the Internet. These devices have rapidly advanced in capability and can do far more that Voice and SMS. Using these capabilities to deliver and execute applications that provide customisable interactivity to mobile phones and other devices is highly desirable but continues to be a challenging endeavour due the varied types of largely incompatible devices and platforms on the market. 
         [0003]    Most interactive applications for mobile phones involve either Short Message Service (SMS) or the development of dedicated applications that address specific business requirements. SMS interactivity suffers from poor usability (the user has to be familiar with idiosyncratic commands) and security issues (SMS source addresses can be faked), thus limiting their usage to simple, non-sensitive transactions. Furthermore, an organisation wishing to use SMS to interact with its customers needs to come to some commercial arrangement with the telecommunications provider in order to establish billing procedures and so on. This can be inconvenient for the organisation, and may also be quite expensive, both to set up and also to operate on an on-going basis. 
         [0004]    The dedicated applications are an attempt to address these shortcomings by developing programming code that is executed by the mobile device to perform a specific task. This involves significant amounts of time, at least because mobile phones from different manufacturers are not usually binary compatible and cannot execute the same executable applications. Additionally, these applications are limited to the functionality required at the time of development, and thus may not support additions or modifications to that functionality. As can be appreciated, distributing changes to these applications is similarly quite a tedious process, typically requiring the user to manually download and install an updated version of the application on their telephone. 
       SUMMARY OF THE INVENTION 
       [0005]    According to one aspect of the invention there is provided a method of delivering an instruction to an application installed on a user device connected to a network, the method comprising the steps of:
       receiving an interactive workflow;   translating the interactive workflow into the instruction in a form executable by the application; and   sending a message including the instruction to the application at the user device.       
 
         [0009]    According to another aspect of the invention there is provided a method of delivering an instruction to a mobile user device connected to a network, the method comprising the steps of:
       receiving an interactive workflow:   translating the interactive workflow into the instruction in a form executable by the mobile user device; and   sending a message including the instruction to the mobile user device.       
 
         [0013]    According to yet another aspect of the invention there is provided computer software comprising executable directions for delivering an instruction to a mobile user device connected to a network, the directions comprising the steps of:
       receiving an interactive workflow;   translating the interactive workflow into the instruction in a form executable by the mobile user device; and   sending a message including the instruction to the mobile user device.       
 
         [0017]    Preferably the step of receiving the interactive workflow includes the step of receiving the interactive workflow coded in a high level programming or scripting language. More preferably the step of receiving the interactive workflow includes the step of receiving the Interactive workflow from an external or third party. 
         [0018]    Preferably the step of sending the message includes the step of sending a set of instructions for execution by an application installed on the mobile user device. More preferably the step of sending the set of instructions includes the stop of sending the set of instructions for the device to interact with a user of the mobile user device. 
         [0019]    Preferably the mobile user device is one of a plurality of mobile user devices and the method also comprises the step of receiving a specification of the mobile user device from a database comprising respective specifications for the plurality of user devices. 
         [0020]    Preferably the step of translating the interactive workflow includes tailoring the instruction to the specification. 
         [0021]    Preferably the step of translating the interactive workflow includes tailoring the Instruction to a device operating system. 
         [0022]    Preferably the step of sending the message includes the step of sending a unique message identifier. More preferably the step of sending the message includes one or more preliminary steps of compressing, encoding and encrypting the instruction. 
         [0023]    Preferably the stop of sending the message includes the step of sending the message via a Short Message Service (SMS) of a cellular network. More preferably the step of sending the message via SMS includes the step of splitting the message into a plurality of messages to comply with one or more standards of the SMS. Alternatively, the step of sending the message includes one or more of the steps of sending the message via a Cell Broadcast Service (CBS) of a cellular network, sending the message as an IP/TCP data packet over a GPRS or 3G network, and sending the message as a data packet over a Bluetooth connection. 
         [0024]    Preferably the method further comprises the step of the mobile user device receiving the set of instructions and the unique message identifier. More preferably the step of the mobile user device receiving the set of instructions and the unique message identifier includes the step of receiving the set of instructions for translation to mobile user device system codes by a workflow execution engine component of the application. 
         [0025]    Preferably the method further comprises the step of receiving a response to the instruction from the mobile user device. More preferably the step of receiving a response includes the step of receiving a response identifier from the device. Even more preferably the method comprises the step of comparing the unique message identifier and the response identifier to confirm the authenticity of the received message. 
         [0026]    Preferably the method includes the step of checking if the mobile user device is willing to receive the instruction derived from the interactive workflow from the external or third party. More preferably the method includes the step of sending a request to the user of the mobile user device to accept the instruction derived from the interactive workflow from the external or third party. 
         [0027]    Preferably the step of receiving the interactive workflow includes the preliminary step of receiving a request for an Application Programming Interface from the external or third party. More preferably the step of receiving a request for an Application Programming Interface is received from the external or third party. Even more preferably the step of receiving the interactive workflow includes the preliminary step of opening an Application Programming Interface. 
         [0028]    Preferably the method also comprises the step of issuing a command to the device to update or delete a sequence of instructions saved to a permanent data store on the mobile user device. 
         [0029]    In accordance with the present invention, there is also provided an interactive process executed by a computer system or device, the process including:
       receiving one or more SMS messages including instruction data representing one or more instructions for execution on said system or device to determine information;   executing said one or more instructions to determine said information; and   sending one or more SMS messages including response data representing said information.       
 
         [0033]    Advantageously, said information may include system information determined from said system or device and/or user information determined from a user of said system or device. 
         [0034]    Preferably, said execution causes generation of an interactive user interface on a display of said system or device, and the process includes receiving response data representing said information from a user of said system or device in response to said interactive display. 
         [0035]    Preferably, said one or more instructions are executed by a virtual machine of said system or device. 
         [0036]    The present invention also provides an application component for a system or device, the application component including:
       a message receiver for processing one or more received SMS messages to generate one or more instructions for execution on said device to determine information;   an execution component for executing said one or more instructions of said application data to determine said information; and   a message sender for generating one or more SMS messages including response data representing said information.       
 
         [0040]    Preferably, the application component further includes a data management component for storing sets of instructions on non-volatile storage means and for retrieving a selected one of the stored sets of instructions for execution. 
         [0041]    Preferably, said execution component is adapted to generate an interactive display for a user of said system or device, and to receive response data representing said information from a user of said system or device in response to said interactive display. 
         [0042]    The present invention also provides an interactive process for execution by a system or device, including:
       receiving message data including header data and encrypted payload data;   selecting one of a plurality of encryption keys on the basis of said header data; and   decrypting said payload data using the selected encryption key.       
 
         [0046]    Preferably, said header data includes index data representing an index for said plurality of encryption keys. 
         [0047]    Advantageously, said payload data may represent one or more instructions for execution on said system or device to determine information. 
         [0048]    Advantageously, said payload data may represent information in response to execution of one or more instructions on a remote system or device. 
         [0049]    The present invention also provides an interactive process for execution by a system or device, including:
       generating payload data for sending to a remote system or device;   selecting one of a plurality of encryption keys;   encrypting said payload data using the selected encryption key;   generating message data for sending to said remote system or device, said message data including header data and the encrypted payload data, wherein said header data includes data representing an index for said plurality of encryption keys to allow said remote system or device to determine the selected encryption key and thereby to decrypt said payload data.       
 
         [0054]    Advantageously, said payload data may represent one or more instructions for execution on said remote system or device to determine information. 
         [0055]    Advantageously, said payload data may represent information in response to execution of one or more instructions. 
         [0056]    Preferably, the process includes generating said plurality of encryption keys and sending said plurality of encryption keys to said remote system or device. 
         [0057]    Preferably, the process includes associating said plurality of encryption keys with an identifier of said remote system or device. 
         [0058]    The present invention also provides an interactive process, including:
       receiving programming instructions for generating an interactive display on a remote system or device:   compiling said programming instructions to generate compiled instruction data;   sending said compiled instruction data to said remote system or device to generate an interactive display on said second remote system or device;   receiving response data representing at least one user response to said interactive display; and   sending response data representing said at least one user response.       
 
         [0064]    The present invention also provides an interactive process, including:
       receiving workflow instructions from a plurality of entities;   processing said workflow instructions to generate interactive applications for execution on a plurality of user devices; and   sending said interactive applications to said user devices for execution.       
 
         [0068]    Preferably, said interactive applications are sent to said user devices using short message service (SMS). 
         [0069]    Preferably, said user devices include mobile telephones. 
         [0070]    The present invention also provides an interactive system for managing interaction with users of remote systems and/or devices, the interactive system being adapted to:
       receive workflow instructions from a plurality of entities;   process said workflow instructions to generate interactive applications for execution on a plurality of user devices; and   send said interactive applications to said user devices for execution.       
 
         [0074]    The present invention also provides a system having components for executing any one of the above processes. 
         [0075]    The present invention also provides a computer readable storage medium having stored thereon program instructions for executing any one of the above processes. 
         [0076]    The present invention also provides an interactive system, including:
       a gateway component for processing received workflow data to generate instructions for generating an interactive display on a user device, the gateway component being adapted to send said instructions to said user device for execution; and   an execution component of said user device to receive and execute said instructions to generate said interactive display, to receive response data representing at least one response of said user to said interactive display; and to send said response data to said gateway component.       
 
         [0079]    Preferably, said user device is a mobile telephone. 
         [0080]    Advantageously, the instructions may be sent to said gateway component in one or more SMS messages. 
         [0081]    Advantageously, said user response data may be sent to said user device in one or more SMS messages. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0082]    Preferred embodiments of the present invention are hereinafter described, by way of example only, with reference to the accompanying drawings, wherein: 
           [0083]      FIG. 1  is a schematic diagram of a preferred embodiment of an interactive system; 
           [0084]      FIG. 2  is a schematic diagram of the high level process and data flow of an interactive process of the interactive system; 
           [0085]      FIG. 3  is a block diagram of a mobile telephone on which a client application of the interactive system is installed; 
           [0086]      FIG. 4  is a block diagram of the client application of the Interactive system; 
           [0087]      FIG. 5  is a flow diagram of the life cycle of an interactive application generated by the interactive process and system; 
           [0088]      FIG. 6  is a block diagram of an application gateway of the interactive system; 
           [0089]      FIG. 7  is a block diagram of a computer system on which the application gateway is installed; 
           [0090]      FIG. 8  is a schematic diagram of the process and data flow of an opt-in process of the interactive system; 
           [0091]      FIG. 9  is a schematic diagram illustrating the use of encryption key sets to establish an encrypted communications channel between the client application and the application gateway; 
           [0092]      FIG. 10  is a schematic diagram of the process and data flow involved in conducting secure communications between the client application and the application gateway; 
           [0093]      FIG. 11  is a schematic diagram illustrating the default behaviour of the interactive system and process whereby a particular application gateway transmits instructions to a particular client application, and the resulting response data is returned to the same application gateway that sent the Instructions; 
           [0094]      FIG. 12  is a schematic diagram similar to that of  FIG. 11 , but illustrating the redirection of response data to a different application gateway from the application gateway that sent the corresponding instructions; 
           [0095]      FIG. 13  is a schematic diagram illustrating the structure of messages exchanged between the application gateway and the client application; 
           [0096]      FIG. 14  is a schematic diagram illustrating the structure of payload data of the messages shown in  FIG. 13 ; 
           [0097]      FIG. 15  is a schematic diagram illustrating the structure of each data part of the payload data of  FIG. 14 ; 
           [0098]      FIG. 16  is a schematic diagram illustrating the fifteen different types of instructions supported by the interactive system and process; 
           [0099]      FIG. 17  is a schematic diagram illustrating the structure of an SMS message generated by the interactive system and process; 
           [0100]      FIG. 18  is a schematic diagram illustrating how the interactive system uses multiple SMS messages to transmit instructions constituting an application whose length is greater than 133 bytes; 
           [0101]      FIG. 19  is a flow diagram of an SMS transmission process of the system; 
           [0102]      FIG. 20  is a flow diagram of an SMS receiving process of the system; 
           [0103]      FIG. 21  is a flow diagram of an application execution process executed by the execution engine of the system; 
           [0104]      FIG. 22  is a schematic diagram illustrating the structure of response data sent from the client application to the application gateway; 
           [0105]      FIG. 23  is a schematic diagram illustrating how the system uses parameter names provided in instructions to label corresponding responses; 
           [0106]      FIG. 24  is a schematic diagram illustrating execution branching in the client application; 
           [0107]      FIG. 25  is a schematic diagram illustrating the use of branch domains to label responses having the same parameter name; 
           [0108]      FIG. 26  is a schematic diagram illustrating the use of a branch name stack to determine control flow; 
           [0109]      FIG. 27  is a schematic diagram illustrating the user interface components resulting from selecting different branches of an interactive application; 
           [0110]      FIG. 28  is a schematic diagram illustrating the inclusion of a ‘back’button on each user interface display; 
           [0111]      FIG. 29  is a schematic diagram illustrating the use of an executed instruction stack to implement the ‘back’ button of  FIG. 28 ; 
           [0112]      FIG. 30  is a screen shot of a user interface of the application gateway for entering scripting language instructions and for submitting those instructions to an instruction compiler of the application gateway; 
           [0113]      FIG. 31  is a source code listing of a function illustrating how the system APIs can be used to send details of a booking to a mobile telephone for display to a user, and to receive the usr&#39;s response indicating whether they user accepts or rejects the booking; 
           [0114]      FIG. 32  is a partial listing of a scripting language application, illustrating the use of control flow branches in the scripting language; 
           [0115]      FIG. 33  is a schematic diagram illustrating the user interface components generated from the scripting language example of  FIG. 32 ; 
           [0116]      FIG. 34  is a schematic diagram illustrating the use of nested user interface displays generated by the system; 
           [0117]      FIGS. 35 and 36  are schematic diagrams illustrating the appearance and structure of general user interface displays generated by the system; 
           [0118]      FIG. 37  is a schematic illustration of a slider control display generated by the system; 
           [0119]      FIG. 38  is a schematic diagram illustrating the use of single and multiple selections in user interface displays generated by the system; and 
           [0120]      FIG. 39  is a schematic diagram illustrating how the branch names of nested menus are used to label parameter data. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0121]    As shown in  FIG. 1 , an interactive system includes at least one client application  102  and at least one application gateway  104 . Each client application  102  is a component of a corresponding user device  106  that can communicate with the at least one application gateway  104  via one or more of a variety of communications means supported by the device  106 , preferably including a combination of (i) an IP-based communications network  108  such as the Internet, (ii) a wireless wide-area communications network such as the global system for mobiles (GSM) telephone network, (iii) a local wireless network or link between the device  106  and the at least one application gateway  104 , such as an infra-red link, WI-Fi or Bluetooth network  112 , and/or (v) a direct cable connection  114  using a standard communications protocol such as RS-232, universal serial bus (USB), or FireWire (IEEE 1394). The interactive system allows an application developer  116  using a standard computer system  118  to rapidly develop and deploy an interactive workflow or application for execution on one or more user devices  106  in order to interact with the users  120  of those devices  106 , and to receive response data representing at least one response of each user  120  to the Interactive application. 
         [0122]    The interactive workflow or application includes a set of instructions for presenting information to a user  120  of each mobile device  106  in an interactive display or user interface, and for retrieving each user&#39;s response(s) to that information. Typically, the information presented to a user  120  will include one or more questions displayed on a display screen of the user&#39;s device  106  (and possibly also audio played on a sound transducer of the device  106 ), and each of the user&#39;s responses is provided by the user interacting with one or more user-interface (UI) components or input controls of the interactive display. Each response can be in the form of freeform text typed into a textbox, or the result of the user interacting with another typo of input control, such as radio buttons, check boxes, sliders, simple menus, nested menus, and so on. To some extent, these possibilities are determined by the capabilities of the device  106 . However, because the workflow supported by the system also includes control flow features similar to those provided by high-level programming languages, the workflow instructions generated by the system are also considered to constitute an interactive software application that is executed on the user device  106 . 
         [0123]    In the described embodiment, the user device  106  is a mobile telephone, but alternatively could be some other type of portable or handheld device such as a personal data assistant (PDA), and hence is also referred to hereinafter as “the mobile device  106 ”. However, even though the device  106  is described as being “mobile” or “portable”, it will be appreciated by those skilled in the art that the systems and processes described herein could alternatively be used in conjunction with other types of devices and systems that need not even be portable. For example, the client application  102  could even be installed on a standard personal computer system (rather than the portable device  106 ) in order to rapidly develop and deliver interactive applications to a standard personal computer, for example. 
         [0124]    In the described embodiment, the client application  102  is a software application that is stored on the mobile device  106 , either as part of the device manufacturing or configuration prior to sale, or subsequently deployed as required via GPRS, Bluetooth, Infrared or a phone specific channel (e.g., a data cable), allowing it to be installed on a wide variety of different types of device. However, it will be apparent to those skilled in the art that the client application  102  and its processes could alternatively be implemented either in part or in total by one or more dedicated hardware components, such as application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs) for example. 
         [0125]    Similarly, the application gateway  104  is a software application that is installed on and executed by a standard computer system  122 , such an Inte™ IA-32 computer server executing a Windows™ operating system. The computer system  122  includes standard hardware components  702 , and software components  704 . The hardware components  702  include at least one processor  706 , a communications interface (e.g., network interface card)  708 , random access memory  710 , non-volatile (e.g., hard disk storage)  712 , user input device (e.g., keyboard, mouse or other pointing device)  714 , and a display adapter and device  716 , all interconnected by a system bus  720 . The software components  704  include the application gateway  104 , and a standard operating system  718  such as Microsoft Windows. Additionally, a third party application  124 , shown as being installed on the developer&#39;s computer  118 , may additionally or alternatively be installed oan the same computer system  122  on which the application gateway itself is located  104 , as shown. However, although the application gateway  104  is described as being a software application, it will be apparent to those skilled in the art that the application gateway  104  and its processes could alternatively be implemented either in part or in total by one or more dedicated hardware components, such as application-specific integrated circuits (ASICs) or field-programmable gate arrays (PPGAs), for example. 
         [0126]    The client application  102 :
       (i) verifies a set of instructions sent by the application gateway  104 ;   (ii) interprets these instructions;   (iii) interacts with the user device  106  and/or the user  120  in accordance with the set of instructions; and   (iv) sends responses back to the gateway  104  or other computer system or device.       
 
         [0131]    The application gateway  104  is effectively a backend component that:
       (i) maintains a database of user devices of the interactive system (i.e., devices on which the client application  102  has been installed);   (ii) generates and delivers interactive applications to the mobile device  106  via any one of a wide range of communication channels;   (iii) ensures the integrity and authenticity of outgoing and inbound messages to and from the mobile device  106 ; and   (iv) provides application programming interfaces (APIs) to allow third-party applications  124  to deploy an interactive application to the mobile device  106  and to receive corresponding responses generated by the client application  102  on the mobile device  106 .       
 
         [0136]      FIG. 2  is a schematic diagram illustrating the high level operation of the Interactive process of the system in relation to the various components shown in  FIG. 1 . At step  202 , an external or third-party application  204  executing on the developer&#39;s computer system  118  (or, alternatively, on the gateway computer system  122 ) calls an API  616  of the application gateway  104  to describe the workflow that the developers of the device  106  want to deploy. In general, the workflow includes the steps of displaying information to a user, and then retrieving at least one response to that information. For example, a typical workflow might be to display a message on the mobile device  106 , ask the user to enter their age, then display another message, and send the age back to the developer. These steps or instructions constitute an interactive application for execution on the mobile device  106 . 
         [0137]    The workflow defines:
       (i) one or more addresses of respective user devices  106 ;   (ii) the steps to be performed on the one or more user devices  106 ;   (Iii) the address of an alternate gateway server (if any)  104  to which responses are to be sent; if no address is given, then the responses will be sent to the same gateway server  104  that sent the application instructions;   (iv) how the response data returned to the application gateway should be processed (e.g., returned to the developer&#39;s application  124 , sent to the developer  116  by email, stored in a file, etc.); and   (v) the communication method(s) that are to be used to send the instructions to the user device  106  and to receive the corresponding response data.       
 
         [0143]    At stop  206 , the application gateway  104  transforms the workflow described by the developer into a compressed, encoded, and encrypted format for transmission to the mobile device  106 . The application gateway  104  also inserts a unique identifier or ID into the message and stores data associating that ID with the destination (e.g., phone number, or network address) to which the workflow is to be sent. 
         [0144]    The application gateway  104  transforms the message so that it can be transmitted via the appropriate communication means. For example, If the message is to be transmitted via SMS, the application gateway  106  splits a large message into smaller messages to comply with the GSM standard. All this is hidden from the developer. At step  208 , the application gateway  104  then transmits the message to the device  106  specified by the developer. 
         [0145]    At step  210 , the client application  102  receives, un-compresses and decrypts the message(s), thereby verifying their integrity. If valid, at step  212  the client application  102  interrupts the user and requests that they complete the workflow. With the user&#39;s cooperation, the client application  102  interprets each instruction and performs a corresponding operation e.g., display a message, collect the user&#39;s age, etc. that in most cases involves interacting with the user of the device  106 . 
         [0146]    At the end of the workflow, the client application  102  scads back to the application gateway  104  all the collected response data via the response channel specified in the workflow instructions by the application gateway  104 . For example, if the response is to be returned via SMS, a response SMS is sent back to a phone number provided in the initial message(s). The client application  102  also encrypts the response message(s) and includes the unique message ID to ensure authenticity of the response. 
         [0147]    When the application gateway  104  receives the response message at step  216 , it decrypts the message and determines whether the ID of the message is valid for the phone number it was received from, using the destination and ID association stored previously. If the message is valid, then it is processed as specified by the developer e.g., passes it on to a third-party application, emails the developer, stores it in a file, etc. 
         [0148]    In addition to the above, the interactive system also provides capabilities for (i) storing (and subsequently updating) a set of instructions as a permanent or semi-permanent application stored on non-volatile storage of the user device  106  for execution at any time; i.e., the application persists on the user&#39;s device; (ii) the distribution of encryption keys; and (iii) opt-in mechanisms to ensure that the mobile device  106  is not sent unsolicited applications, e.g., if the application gateway  104  is shared by multiple vendors. 
         [0149]    The interactive system and the interactive process executed by the interactive system are described in detail below. 
         [0150]    As shown in  FIG. 3 , the mobile device  106  is a standard mobile phone including hardware components  302  and software components  304 . The hardware components  302  include a processor  306 , read-only memory  308 , random-access memory  310 , flash memory  312 , user interface components including user input components  314  (e.g. microphone, keyboard, and, in some devices, touch-screen), output components  316  (e.g., display screen, speaker), and one or more comminations interfaces  318  allowing the device  106  to communicate with a mobile phone network  110 , and, in some devices, also Bluetooth and/or Wi-Fi local wireless networks or an infrared link  112 . In the preferred case of the mobile device  106  being a telephone, the device  106  also includes a SIM card  320 . The software components include an operating system  322  such as the closed, proprietary operating systems installed on mobile telephones sold under brands such as Nokia and Motorola, Java platform Micro-edition (Java ME)  324 , and the client application  102 . However, if the operating system  322  is a more sophisticated operating system such as Symbian, Linux, Microsoft SmartPhone, PocketPC, Windows CB, or Windows Mobile, that provides sufficiently powerful application programming interfaces (APIs), then the J2ME component  324  can be omitted. As shown in  FIG. 4 , the client application  102  includes a message sender component  402 , a message receiver component  404 , user interface (UI) widgets  406 , a workflow execution engine  408 , instant data storage  410 , and permanent data storage  412 . The client application  102  is a native application that is executed by the mobile device  106 . The client application  102  can be installed by any one of a number of means, including WAP push, IP data packets (GPRS or 3G networks), Bluetooth, Infrared, or a phone-specific channel such as a data cable. The client application  102  can be provided as a preinstalled application on the mobile phone  106  when purchased. 
         [0151]    The message sender  608  sends response messages to the application gateway  104  in a format understood by the application gateway  104 . It encrypts the message and includes ID provided with the initial application to confirm its authenticity. 
         [0152]    The message receiver  606  decrypts and uncompresses instruction sets received from the application gateway  104 . It implements message reception via a number of channels, including Bluetooth, Infrared, IP networks (GPRS or 3G), and SMS. The message receiver  606  also invokes the workflow execution engine  408  to process the instruction set. 
         [0153]    The UI Widgets  406  are pre-built user interface components that instructions sent by the application gateway  104  can use to interact with the user. 
         [0154]    The workflow execution engine  408  is responsible for running and maintaining state for the instructions currently being processed. It associates instructions with UI widgets as well as storing input from the device  106  and its user. It is also responsible for invoking the message sender  402  once the workflow is completed to initiate sending the response to the application gateway  104 . The workflow execution can also be invoked by a timer if an instruction asks to be nm at a specific time. 
         [0155]    The client application  102  can simultaneously receive multiple workflow applications at any one time, and the instant data store  410  is effectively a first-in, first-out queue that stores these applications and processes them one by one until the instant data store  410  is empty. 
         [0156]    The interactive system has the ability to make a sequence of instructions persistent on the mobile device  106  as an application. These sequences are identified by a unique label and are stored in the permanent data store  412 , being in this embodiment the non-volatile flash memory  312 . The application gateway  104  can issue commands to update or delete applications in the permanent data store  412 . 
         [0157]      FIG. 5  is a flow diagram illustrating the life cycle of an execution instance of the client application  102  following, receipt of an instruction from an application gateway  104 . However, the client application  102  can be invoked at step  502  by either a new data event or a timer event. A new data event occurs when the client application  102  is activated by the mobile device  106  when now payload data addressed to the client application  102  is received. Timer events are set by a specific instruction that suspends execution of the instruction to a later date/time. The workflow engine  408  is responsible for scheduling the client application  102  to start and process the instruction set at that date/time. 
         [0158]    Once invoked, at step  504  the instruction sequence is retrieved either reading data from the instant data store  410 , in the case of a timer event, or from the input channel in the case of a new data event. If the instruction data is retrieved from the input channel and is encrypted, at step  506  the client application  102  decrypts and verifies it as described below. If the data is valid, the workflow execution begins at step  508 . 
         [0159]    The workflow execution  508  processes the instructions step by step. This may or may not involve user interactions (as some instructions described in the Appendix can be handled without user interaction). Upon execution of a timer instruction specifying that execution should be postponed to a later time, further execution of instructions of the workflow application is suspended and the instruction set is stored placed in the instant data store  410  pending resumption at the specified time. 
         [0160]    Once the workflow execution  508  is complete, the workflow application is removed from the instant data store  410 . If the application is marked as persistent, the instruction act is saved to the permanent data store  412 . The user can then invoke the instruction set at any time. 
         [0161]    At step  510 , the Information collected by the workflow execution  508  is sent back to the application gateway  104  as response data. The client application  102  encrypts the response data in addition to including the unique message ID that verifies the authenticity of the response data. 
         [0162]    As shown in  FIG. 6 , the application gateway  104  includes an instruction compiler  602 , a key manager  604 , a message receiver  606 , a message sender  608 , an opt-in manager  610 , persistent storage  612 , and an application programming interface (API)  616 . 
         [0163]    The instruction compiler  602  translates workflow descriptions received from the developer  116  into a format that is optimized for delivery to and execution by the client application  102 . The workflow description is written in a scripting language that is compiled by the instruction compiler  602 . The developer can enter the workflow description directly into a text box and submit its contents to the compiler  602 . This is typically used to rapidly prototype the look and feel of a workflow application. Alternatively, the workflow description can be submitted by making an API call to the compiler  602  from a high-level programming language such as C#, Java, or TCL, thus providing end-to-end application integration. 
         [0164]    The message sender  608  encrypts the workflow instruction set. The encryption relies on requesting the key manager  604  to provide a random index and an encryption key that is specific to a particular user device  106  on which the instructions are to be executed. The index is sent in cleartext to the client application  102 , which uses the index to look up the appropriate encryption key to decipher the message. The message sender  608  also generates a unique random identifier for the workflow application. The random identifier is a combination of a random identifier and an identifier of the party who sent the workflow description. 
         [0165]    The message sender  608  uses the transport adapter  614  to deliver the actual message(s) containing the workflow application. The message sender  608  first checks with the Opt-in manager  610  to ensure that the client application  102  does not receive unsolicited applications which it has not opted into, as described below. 
         [0166]    The transport adapter  614  abstracts the various methods of delivering an instruction set to the client application  102  on the mobile device  106 . It uses device capability information stored in the persistent storage  612  to determine the capabilities of the device  106  and hence the best communication channel to deliver the message(s). 
         [0167]    The transport adapter  614  provides plug-in support for new channel types dynamically by providing a set of messaging APIs and by allowing dynamic loading of compiled code that implements a new messaging interface. If required, the transport adapter  614  reformats the instruction payload so that it can be delivered via a particular channel. In particular, an application delivered by SMS may have to be divided into two or more smaller messages due to SMS message size limitations. 
         [0168]    The key manager  604  is responsible for generating, distributing and managing the encryption keys issued to the portable device  106 , as described below. It also provides encryption and decryption facilities for the message sender  608  and the message receiver  606 . 
         [0169]    The opt-in manager  610  provides an opt-in, opt-out process to allow client applications  102  select the entities they are willing to receive instruction sets from. This is desirable because the application gateway  104  may be shared by multiple parties and the client application  102  will otherwise execute any received instruction set as long as it is valid. The opt-in manager  610  maintains in the persistent data store  612  associations between parties and the phone numbers (or, in the case of devices other than telephones, other form of address or identifier of the destination device) they are allowed to send applications to. The process for creating these associations can be dynamic to allow users to selectively block or allow instructions form particular parties. For example,  FIG. 8  shows the message flow for an opt-in process. 
         [0170]    At step  802 , a party uses the external application  124  executing on the computer system  118  to send a workflow description to the application gateway  104 , which at step  804  compiles and formats the instructions in preparation for sending them to a client application  102  that has not opted in. At step  806 , the message sender  608  first checks whether the client application  102  has opted in. If not, at step  808  it asks the opt-in manager  610  to determine the opt-in status for this party and this user device. At step  810 , the opt-in manager  610  sends an opt-In request message to the user, asking whether they agree to receive applications from this party. If the response is yes, at step  812  the opt-in manager  610  stores this information in the persistent data store  612  and then at step  814  instructs the message sender  608  to send the Instruction set at step  816 . Otherwise, if the response is no, then the message sender  608  fails and notifies the party at step  818  that the user has not opted in. 
         [0171]    Alternatively, the opt-in process could be performed manually, for example, by using a form that enables the user to directly add entries to the persistent data store  612 . Alternatively, an analogous process could be used to opt-out of receiving applications from a particular party. 
         [0172]    The message receiver  606  receives messages from the client application  102  and communicates with the transport adapter  614  to receive responses via any of the supported transport channels and protocols, including GPRS, IP network, Bluetooth, and SMS. For example, the instruction set of the interactive system allows instructions to be received by one physical channel/protocol (e.g., SMS), and a corresponding response to be delivered by another (e.g. Bluetooth). 
         [0173]    When a message is received, the message receiver  606  first logs the message for audit purposes. Then it checks the authenticity of the message by deciphering the message using the key manager  604 , and examining the unique message ID and the party ID to confirm that they match what was sent out. 
         [0174]    Once the message authenticity is established, the message receipt is logged for billing and auditing purposes. Finally, the response message is processed as required by the party. This may include emailing the party; logging it to a file for the party to collect; and/or making a request to a third-party application to process the message. The actual method(s) used to process the response message can be specified when calling the API. If the API call does not specify a processing method, then the response is processed using the default method configured for the corresponding developer, determined when the developer establishes an account with the provider of the interactive system. 
         [0175]    The persistent storage  612  is a non-volatile storage component that is used by:
       (i) the key manager  604  to store the encryption keys for the various mobile devices;   (ii) the message sender  608  to store the addresses of user devices  106  (e.g., phone numbers in the case of the device  106  being a telephone), together with the delivery mechanisms that each user device  106  supports. It also stores the Identifiers of the messages that have been sent out, for verification purposes;   (iii) the message receiver  606 , to store received messages for audit and billing purposes; and   (iv) the opt-in manager  610 , to store opt-in data representing each user device  106  and the third party applications that are authorised to send instructions to each user device  106 .       
 
       Encryption Keys 
       [0180]    As described above, each installed instance of the client application  102  on a user device  106  is identified by a unique client identifier (also referred to herein a the client ID number) that is associated with its phone number. When a client application  102  is first installed on a mobile device  106 , a number of private encryption keys are generated and associated with the client ID. 
         [0181]    As shown schematically in  FIG. 9 , these encryption keys are then used by the client application  102  to authenticate the payload data and to encrypt the response data. On each payload or response data packet or message, the index of the appropriate encryption key is indicated in the header of the payload. 
         [0182]      FIG. 10  is a schematic diagram illustrating the message and process flow for generating and updating encryption keys on a client application  102  and an application gateway or backend system  104 . The process is initiated by the client application  102  making a secure communication activation request to the application gateway  104  at step  902 . In response, the application gateway  104  generates and stores a set of private encryption keys, and associates these with the client ID at step  904 . At step  906 , the application gateway  104  sends these newly generated private keys to the client application  102 . The client application  102  stores the received private keys on the persistent storage  412  at step  908 , and returns an acknowledgement to the application gateway  104  at  910 , confirming that the private keys have been stored (or updated if the keys had been previously stored). This completes the generation/update steps and secure communication is activated at step  912 . This involves encrypting a message payload using one of the private encryption keys, which can be selected at random or on any other basis at step  914 . At step  916 , the secured payload encrypted with the selected key is sent to the client application  102 , together with a message header specifying the index of the selected encryption key. At step  918 , the client application uses the encryption key index indicated in the header to select the appropriate private key, and uses that key to decrypt the payload data at step  918 . After performing the application instructions specified by the payload, the client application  102  then encrypts the response at step  920 . The response can be encrypted using the same key, as shown in  FIG. 10 , or any other of the stored keys. The secured response is sent to the application gateway  104  at step  922 , and the response is decrypted using the appropriate response key at step  924 . As will be understood by those skilled in the art, the use of private encryption keys greatly improves the security of communication, and the use of a set of encryption keys, rather than a single key, further increases this security. 
         [0183]    When sending a response message, the client application  102  uses the source address of the corresponding payload data by default. This effectively provides multiple client-server communication channels in between the backend  104  and the client application  102 . For example,  FIG. 11  shows an arrangement whereby two instances of the client application  102 , a first instance  1002  and a second instance  1004 , are in communication with two instances  1006 ,  1008  of the application gateway  104 , via a wireless communications network  110 . A message  1010  sent from the first backend system  1008  to the second client application  1004  includes an address  1012  of the first backend system  1008  in the header of the message  1010  so that when the client application  1004  sends the corresponding response  1014 , it is addressed to the first backend system  1008 . 
         [0184]    In contrast,  FIG. 12  shows the same arrangement whereby a message  1102  also includes the address  1012  of the first backend system  1008 . However, workflow instructions contained in the payload data can alter this default behaviour by redirecting the response to another backend server instead. This mechanism is activated by a DIVERT command in the payload data, described further in the Appendix. Specifically, in this message  1102  the payload  1104  includes a divert instruction with the address of the second backend system  1006 . Consequently, after the second client application  1004  executes this instruction, the response  1106  is addressed to the second backend system  1006 , rather than the first backend system  1008  that originated the message  1102  containing the instructions. Because the second backend system  1006  does not have direct access to the client ID and message ID pair, or the encryption keys for the client application  102 , the second backend system  1006  calls an API of the first backend system  1008  to check the integrity and authenticity of the response data. If the payload was encrypted, then the first backend system  1008  decrypts the payload and sands it back to the second backend system  1006  over a secured communications channel (using SSL, for example). In an alternative embodiment, the encryption keys are stored in a centralised component of the interactive system, and all encryptions and decryptions are performed in this manner. 
       Communication Data Payload 
       [0185]    The payload exchanged between the client application  102  and the backend system  104  is binary data—a sequence of bytes. The communication channel for this payload can include SMS or Cell Broadcast Service (CBS) messages; IP/TCP data packets (over GPRS, 3G or other type of data networks); and/or Bluetooth data packets. 
         [0186]    As shown in  FIG. 13 , each data payload is prefixed with a header  1204  which indicates whether the payload is encrypted with an encryption key. The header data contains the index of the encryption key stared in the client application key-storage, thereby allowing the client application  102  to decrypt the payload data. 
         [0187]    As shown in  FIG. 14 , plain payload data (either unencrypted or after being decrypted) contains a series of variable-length data parts that instruct the dynamic workflow execution engine  508  of the client application  102  to construct the user UI workflow. 
         [0188]    As shown in  FIG. 15 , each data part includes type  1402  and length  1404  data fields, followed by the actual instruction data  1406 . The type field is a single octet or byte that defines the type of workflow instruction that follows. The length indicates the number of octets or bytes of the instructor data  1406 . 
         [0189]    As described above, the interactive system is able to use one or more of a variety of different communication channels for sending and receiving messages and responses between the application gateway  104  and the client application  102 . For most of these different communication channels, the communication itself is straightforward, using the standard methods and libraries available and known to those skilled in the art. However, the Interactive system supports message and response delivery via the short message service, or SMS. SMS is defined in the GSM 03.40 specification, which defines an upper limit on the size of each SMS message. Specifically, each SMS message is capable of containing up to 140 bytes of data, equivalent to 160 ASCII characters when using 7-bit encoding, as shown in  FIG. 17 . The interactive system sends SMS messages including 8-bit (binary) data and including a 7-byte user data header or UDH  1702 , as described in the GSM 03.40 specification. The UDH  1702  consists of a length field or UDHL  1704 , specifying the length of User Data Header in bytes as specified in OSM 03.40, and a 6-byte User Data Header field  1706  specifying the destination address of the payload data  1708 . 
         [0190]    The UDH data  1702 —specifying the destination of the binary message—is interpreted by the mobile device to deliver the payload data to the client application  102 . Excluding UDH data  1702 , each SMS message is capable of carrying 133 bytes of payload data  1708 . 
         [0191]    If the payload data exceeds this length, the payload data is sent in two or more SMS messages  1804 , each message containing up to 127 bytes of payload data  1806 ,  1808 , as shown in  FIG. 18 . These SMS messages  1804  have a section of User Data Header indicating that they all belong to a concatenated message, as described in the GMS 03.40 specification. A byte padding mechanism is used by the backend system  104  and the client application  102  when the payload is sent in multiple SMS massages. In this mechanism, a padding or termination byte  1810  with value 0xFF is appended to the end of each payload data fragment  1806 ,  1808  when sent out from the backend system  104 . The client application  102  removes these padding bytes  1810 , which appear as stuffed bytes  1812  in the concatenated payload data before passing the payload data  1814  to the workflow execution engine  408 . The byte padding mechanism is used to eliminate problems found in a number of mobile phone models that strip out the last byte of every concatenated data fragment. 
         [0192]    The instruction compiler  602  creates the payload data from the compiler output to generate binary SMS messages. Construction of binary messages includes splitting the payload data  1802  into multiple SMS messages  1804  if the data length exceeds the single message capacity of 133 bytes.  FIG. 19  is a flow diagram showing the steps involved in this process. 
         [0193]    As shown in  FIG. 19 , when delivering a message or a response via SMS, at step  1902  a check is performed to determine whether the size of the payload data exceeds 133 bytes. If not, then at step  1904  a user data header is added, and a single SMS message is composed and sent at step  1906 . Alternatively, if the payload length does exceed the maximum size that can be sent in a single SMS message, then at step  1908  a concatenated message identifier is generated, and at step  1910  the number of concatenated messages that are required to accommodate the payload data is determined. Then, a processing loop consisting of steps  1912  to  1920  composes the appropriate number of SMS messages as follows. At step  1912 , the next payload portion is selected and copied to the payload of the current SMS message. At step  1914  a user data header is added, including the identifier indicating that the SMS message is part of this SMS message set. At step  1916 , a padding or termination byte is appended to the payload data, as described above. Finally, at step  1918  the resulting SMS message is sent. These steps  1912  to  1918  are repeated until the test at step  1920  determines that the last part of the payload data has been sent, and the process then terminates. 
         [0194]    Removal of stuffed bytes in the payload data is handled by the client application  102  by searching for the specific stuffed byte octet value (0×FF in this embodiment) and removing it from the payload data, as shown in  FIG. 20 . 
         [0195]      FIG. 16  is a schematic diagram showing the fifteen different instructions supported by the interactive system, showing the respective type bytes identifying each instruction type, and the structure of the corresponding instruction parameters. Further details on the various instructions are provided in the Appendix. 
       Dynamic Workflow Execution Engine 
       [0196]    The client application  102  presents to the user a number of user interface (UI) widgets  406  as well as executing user-invisible routines. This allows the client application  102  to display information as well as capture device information and/or user inputs. 
         [0197]    The UI widgets  406  typically include the following type of user interface components and controls:
       (i) Message screen: to show textual information;   (ii) Selection menu: to ask for the user&#39;s selection of one of a number of defined choices (i.e., radio buttons);   (iii) Multiple choices: to ask for user&#39;s one or more choices (i.e., check boxes);   (iv) Textual input: to retrieve free form text input from the user (textbox);   (v) Numeric or date inputs: to retrieve user input data, restricted by type; and   (vi) Widgets displayed when branching and jumping amongst execution steps.       
 
         [0204]    However, this list of UI widgets  406  and their actual screen layouts can vary depending on the platform (i.e., on each combination of device hardware and operating system software) on which the client application  102  is installed. 
         [0205]    The client application  102  implements a workflow execution process  2100 , as shown in  FIG. 21 , on each invocation to execute a workflow application. The workflow execution process  2100  begins after the client application  102  is invoked at step  2102 , and a test is performed at step  2104  to determine whether the invocation has resulted from the receipt of new payload data from the application gateway  104 . If so, then at step  2105  the new payload instructions are retrieved, and than parsed at step  2110 . Otherwise, if the invocation was not due to the receipt of now payload data, then a test is performed at step  2106  to determine whether instructions are contained in the instant data storage  410 . If so, then the instructions are received from the instant data storage  410  at step  2108 , and then parsed at step  2110 . Otherwise, another test is performed at step  2132  to determine whether any sets of instructions have been saved as, applications in the permanent data storage  412 . If not, than at step  2134  an information message is displayed to the user indicating that there are no applications (Instant or permanent) in the queue. Once the user acknowledges this information message, or when a corresponding timeout period has elapsed, the client application  102  is terminated. Alternatively, if the permanent data storage  412  contains one or more permanently stored sets of instructions (i.e., applications), then at step  2136  these are displayed to the user, and the process  400  pauses at step  2137 , awaiting the user&#39;s selection of one of these, or selection of a quit option. If, at step  2138 , it is determined that the user has selected the quit option, then the client application  102  terminates. Otherwise, the user has selected a permanently stored set of instructions, and these are retrieved at step  2140 , and then parsed at step  2110 . 
         [0206]    Following parsing of the workflow instructions at step  2110 , the first or next workflow instruction is read at step  2112 , and executed at step  2114 . If it is determined at step  2116  that the instruction is a UI instruction, then the process waits to receive user input at step  2118 . Once the user&#39;s response has been received, at step  2120  the UI widget displayed on the screen of the device  106  is removed, and any user input is stored at step  2122 . At step  2124 , a test is performed to determine whether the instruction was the last in the workflow. If not, then the process loops back to step  2112 . Otherwise, once all of the instructions have been executed, then a response message is composed at step  2126 , and sent at step  2128 . If the workflow instructions executed are stored in the instant data storage  410 , then they are deleted at step  2130 . This terminates the workflow execution process  2100 . 
       Parsing Workflow Instructions and Response Data 
       [0207]    The workflow execution engine  408  of the client application  102  interprets the payload data parts and generates the dynamic UI workflow accordingly. 
         [0208]    The data parts from the payload data are indexed sequentially when read by the workflow execution engine  408 , and, this is also the default order of workflow execution  508 . As shown in  FIG. 22 , the response data includes each response in the same order as the corresponding instructions were received and executed. When a workflow instruction is executed and response data is to be retrieved, a parameter name is included in the instruction data, and the user response or system response is associated with this parameter in the response. All the instruction responses are included in the response data when the workflow is completed, as shown in  FIG. 23 . 
       Jumping and Branching in the Workflow 
       [0209]    The workflow execution engine  408  provides a mechanism to allow branching and jumping in the sequence of instructions. 
       Branching 
       [0210]    Because an instruction might be involved in different branches through out the workflow, the workflow execution engine  408  differentiates the instruction response data for different branches using branch domains. A branch domain specifies the address of a workflow instruction in the workflow tree. When setting the instruction response data, the response parameter name is prefixed with the corresponding branch domain, separated by a period character. For example, an instruction to retrieve user input for a numeric-valued parameter with the parameter name “number” could be called from two different branch menus: one named “First branch”, and the other named “Second branch”. In both of these cases, the instruction returns the same parameter name “number” but with different values. The workflow execution engine  408  associates a branch domain with the parameter name to differentiate the two response values. Thus in this example, the first value is returned as “First branch.number=xxx” and the second value as “Second branch.number=yyy”, where “xxx” and “yyy” represent the actual values entered by the user.  FIG. 25  shows a more complex example where menu selections are nested. 
         [0211]    Additionally, the branch domain is appended with a branch name on selection of a branch menu. For example, in an application with two nested branch menus  3902  “Service Request” and  3904  “Water Service” as shown in  FIG. 39 , when the user selects item  3910  “Water” in menu  3902 , and then selects item  3912  “Pipe Burst” in the subsequent branch menu  3904  “Water Service”, and than fills out  3914  with “John Doe” in the text input screen  3906  “Your name”, the client application  102  will internally send the response as “Water.Pipe burst.name=John Doe”. When the BRANCH_BACK command is executed, the previous branch name is removed. The workflow execution engine  408  uses a branch name stack to maintain the order of branch names as they are selected. 
         [0212]    For usability reasons, when working with a multiple branch menu, it is important for the user to know whether or not a branch has already been visited by the user. To this end, the workflow execution engine  408  indicates visited branch menu items by displaying an image adjacent to those branches to indicate that they have already been visited by the user. For example, as shown in  FIG. 27 . 
         [0213]    When the user has visited user input screen  2702  to enter data  1 , an image icon  2706  is displayed adjacent to the first branch menu item  2704  is marked with distinct. This allows user to visually distinguish those parts of the workflow that have been visited from those parts that have not been visited. Alternatively, the visited branches could be displayed in a different colour, as used by web browsers to indicate that a hyperlink has been visited. 
       Backward Navigation 
       [0214]    As shown in  FIG. 28 , all of the user interface screens include a “Back” navigation button  2802  to allow the user to return to the previous screen within the workflow. The position of this back button can change depending on the specific mobile device platform executing the client application  102 . As shown in  FIG. 29 , the workflow execution engine  408  maintains an ordered list or stack of instructions that cause a change in the screen or display, and selection of the “Back” button causes the execution to return to the previous instruction. 
       Sending a Workflow Description to the Instruction Compiler 
       [0215]    As described above, a developer  116  can send a workflow description to the instruction compiler  602  of the application gateway  104  by submitting programming instructions written in the programming language supported by the instruction compiler  602 , using a hypertext transport protocol (HTTP) interface of the instruction compiler  602 . For example,  FIG. 30  is a screenshot of an HTML webpage generated by the application gateway  104 . The webpage includes a scrollable text box  3002  into which the developer  118  can directly enter commands in the scripting language, and a compile button  3004  which, when pressed, submits the text in the scrollable text box  3002  to the instruction compiler  602  for compilation. 
         [0216]    The scripting language of the interactive systems is a high level language for describing the workflow of an interactive application. It is similar in vein to BASIC and can be learnt quickly by a programmer who has a basic knowledge in programming. 
         [0217]    Alternatively, a workflow description can be sent to the instruction compiler  602  by invoking API calls to the application gateway API  616 . For example,  FIG. 31  shows a source code listing of a J2ME function SendworkflowRequest that is used to generate and send workflow instructions to the mobile telephone  106 . In this example, the workflow instructions are to display booking details to the user  120  and then retrieve the user&#39;s response indicating whether the user  120  accepts or rejects the booking, together with the user&#39;s name and telephone number. The workflow API is first initialised by creating (at  3102 ) a new J2ME Commando object named WorkflowCommand. A workflow header, as described below, is then added at  3104 . Workflow instructions are then added in the order of desired execution by calling APIs that are provided as methods of the workflowCommand object. Each type of workflow instruction is added by calling a corresponding API function with a set of parameters. For example, the object method AddInfoMessage is used (at  3106 ) to add an instruction that displays a screen of information to the user. The first argument to this method provides a title for the screen, and the second argument provides the actual text information that is displayed. Similarly, the method AddSingleMenu adds (at  3108 ) an instruction that displays a single-level menu (i.e., radio buttons) to the user, allowing the user to select one item from a list of items provided as a parameter to the method. In this example, the two items are displayed as “Accept”, and “Reject”, and the user response indicates whether the user  120  accepts or rejects the booking. 
         [0218]    The method AddUserInputCmd (at  3110  and  3112 ) displays a text string to the user, together with a textbox, prompting the user to enter an appropriate input value. The first parameter to this function finds the name of the parameter that will be associated with the returned input value. The second argument provides a string that is displayed to the user, and a third argument allows the developer to restrict the type of input; for example, to a phone number, email address, and so on. 
         [0219]    Finally, the AddRedircetHeader method (at  3114 ) defines a return address or phone number to which the response will be redirected, as described above. The communication channel to be used (e.g., whether by SMS, IP network, Bluetooth, etc) is also specified in the header. 
         [0220]    Once the workflow instructions are added, the workflow API is called again (at  3116 ) to compile the instructions and build the payload data to be sent to the client application. The workflow API is called as many times as needed (at  3118 ) to send multiple messages if required. 
       Scripting Language Overview 
       [0000]    
       
         
           
             Instructions are written line by line. 
             Comment lines start with // 
             Label lines start with # 
             String parameters are delimited by double quote characters “ ” 
           
         
       
     
       Workflow-Programming Structure 
       [0225]    Commands are processed sequentially line by line. Three instructions are provided to create tree structures of the workflow: BRANCH_TO, BRANCH_BACK, and GOTO. BRANCH_TO and BRANCH_BACK are used in combination to create a subroutine for the compiled program. GOTO is a jump instruction that allows program execution to jump to a specified line in the script. Comment and blank lines are ignored by the instruction compiler  602 . 
       Command Line Syntax 
       [0226]    A command is a line in the script which has the following structure.
       &lt;Command Name&gt; &lt;String Parameter&gt; &lt;String Parameter&gt; &lt;Label&gt;   Where
           &lt;Command Name&gt; is a command.   &lt;String Parameter&gt; is a qualified string value, i.e., delimited by double quote characters. For example, “User name” is a string parameter. There can be more then one string parameter in each command.   &lt;Label&gt; is the name of the label that is associated with the command. Labels can only be used with the GOTO command and the ITEM command when used in conjunction with BRANCH_TO command.   
               
 
       Comment 
       [0232]    There is no block comment in the language. Comment lines are lines that start with // (two forward slash characters followed by a space character). 
       Example 
       [0000]    
       
         
           
             // this is a comment line 
           
         
       
     
       Label 
       [0234]    A label is a way to mark a line number so that it can be referred to in GOTO and BRANCH_TO&#39;s ITEM commands. A label line starts with #(hash) character, followed by a space character. The label name is the next word from the #character. 
       Example 
       [0000]    
       
         
           
             For label START, the line looks like this: 
             #START 
             The label name is mapped to the index (i.e., relative position in the script) of the command immediately following the label line. 
             Labels in a script must be unique, a compile error occurs if a duplicate label is detected. All labels are parsed in the first pass of the compiler, building a mapping of label and command index to be used in the second pass. 
           
         
       
     
       Backward Navigation 
       [0239]    As described above, a “Back” navigation button is attached to all displayed screens by default. This button allows backward navigation of the workflow executed on the user device  106 . On most mobile phone platforms, this “Back” button is mapped to the right action key. However, this can change depending on the type of phone. 
       Tree Navigation 
       [0240]    A combination of the BRANCH_TO command, labels, and the BRANCH_BACK command allows the workflow to support a tree like execution structure, as shown in the source code listing of  FIG. 32  and the resulting display screens of  FIG. 33 . A detailed description is provided below. When a user is navigating thought workflow screens, the state of each screen (Item selection and user inputs) is not remembered. 
       Example 
       [0241]    The following is a source code listing that is used to generate an interactive application for execution on a user device such as the mobile telephone  106 . The source code defines a workflow that allows the user  120  of the mobile telephone  106  to generate a service request for water, electricity, and/or gas services. The listing is arranged in four groups of commands or paragraphs under respective labels. The first paragraph, labeled START, results in display of a main screen  3402 , as shown in  FIG. 34 . The BRANCH_TO command has two parameters. The first, “serv” defines a branch name for this branch, and the second parameter, “Service Request” defines the title that is displayed at the top of the main screen  3402 . The subsequent three commands define items that can be selected by the user to invoke corresponding workflow branches. For example, the first ITEM command has two parameters. The first parameter, “Water”, defines the text  3404  that is displayed on the main screen  3402 , and that can be selected to invoke the corresponding workflow branch. The second parameter, in this case “WATER”. Is a label of the corresponding workflow branch, in this case referring to the second group or paragraph of commands grouped under that label. Thus if the user navigates the main screen  3402  to select the first item  3404 , the workflow jumps to the SELECT ITEMS, causing display of a water service selection screen  3406 . In this case, the three items are simply menu selections (rather than workflow branches), and thus selection of any one of these items causes the appropriate parameter, in this case named “water” to be assigned a value defined with the corresponding item. For example, if the user selects the second item, “Leaking”  3408 , then the parameter “water” is assigned the value “Leaking”. Once this item has been selected, the workflow proceeds to the following command, which in this case is the BRANCH_BACK command, which returns control to the main screen  3402 . 
         [0242]    In this manner, the user can select the Electricity item  3410  to branch to the ELECTRICITY workflow, resulting in display of a Electricity service screen  3412 . Similarly, the user can select the “Gas” request item  3414  to cause a Gas service screen  3416  to be displayed. Once the user is satisfied with the service requests thus defined, selection of the Next button  3418 , or the OK button  3420  causes execution to continue to execute in this example the command “GOTO CONTACTS”, which causes the workflow to jump to the command following the CONTACTS label, being in this case an INPUT command displaying a name input screen  3422 , and subsequently a contact number screen  3424 . Once the OK button  3426  on the Contact numbers screen  3424  has been selected, a MESSAGE command causes display of a Service Info screen  3428  providing informational feedback to the user, in this case confirming that the service request will or has been sent to an appropriate party for processing the user&#39;s request. 
         [0000]    
       
         
               
               
             
               
               
               
             
               
               
             
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 // Start of program 
               
               
                   
                 # START 
               
             
          
           
               
                   
                 BRANCH_TO “serv” 
                  “Service Request” 
               
               
                   
                 ITEM 
                  “Water” WATER 
               
               
                   
                 ITEM 
                  “Electricity” ELECTRICITY 
               
               
                   
                 ITEM 
                  “Gas” GAS 
               
               
                   
                 GOTO 
                  CONTACTS 
               
               
                   
                 # WATER 
               
               
                   
                 SELECT 
                  “water” “Water service” 
               
               
                   
                 ITEM 
                  “Pipe Burst” 
               
               
                   
                 ITEM 
                  “Leaking” 
               
               
                   
                 ITEM 
                  “New connection” 
               
               
                   
                 BRANCH_BACK 
               
               
                   
                 # ELECTRICITY 
               
               
                   
                 SELECT 
                 “elect” “Electricity service” 
               
               
                   
                 ITEM 
                  “Fire” 
               
               
                   
                 ITEM 
                  “New connection” 
               
               
                   
                 ITEM 
                  “Disconnection” 
               
               
                   
                 BRANCH_BACK 
               
               
                   
                 # GAS 
               
               
                   
                 SELECT 
                 “gas” “Gas service” 
               
               
                   
                 ITEM 
                  “Leaking” 
               
               
                   
                 ITEM 
                  “New connection” 
               
               
                   
                 ITEM 
                  “Fire” 
               
               
                   
                 BRANCH_BACK 
               
             
          
           
               
                   
                 // This is like a subroutine 
               
             
          
           
               
                   
                 # CONTACTS 
                   
               
               
                   
                 INPUT 
                  “name” “Your Name” ANY 
               
               
                   
                 INPUT 
                  “phone” “Contact Number” NUMERIC 
               
               
                   
                 // message is sent here 
               
               
                   
                 //# END 
               
               
                   
                 MESSAGE 
                  “Service Info” “Your request will be 
               
               
                   
                   
                  sent to XXXX” 
               
               
                   
                   
               
             
          
         
       
     
       Script Commands and Syntax 
     HEADER Command. 
       [0243]    The HEADER command is used to include a specified piece of text at the beginning of the response message when the workflow has been executed. This command is invisible to the user of the user device. This command is used as a context identifier for server-client conversation. 
         [0244]    There can be multiple header commands in the script. When using the HEADER command in conjunction with the BRANCH_TO command, different response message prefixes can be set, based on the user&#39;s selection. 
       Syntax 
       [0000]    
       
         
           
             HEADER &lt;header&gt;
           &lt;header&gt; is a string parameter to be prepended to the response text message.   
         
           
         
       
     
       Example 
       [0000]    
       
         
           
             HEADER “timesheet” 
           
         
       
     
       Response 
       [0248]    &lt;header&gt; is attached to the beginning of the response message. If there are multiple headers to be included in the response message, the response headers are prepended based on their execution order in the workflow. 
       DIVERT Command 
       [0249]    The DIVERT command is used to redirect a response message to a telephone number or address different from that of the source of the original instructions. Normally, the response message is sent back to the source address of the payload, but the response message can be sent back to another number instead by including a DIVERT command in the workflow. This command is invisible to the user. There can be multiple DIVERT commands in the script, but the last one that is executed in the workflow takes effect. When combining this command with the BRANCH_TO Command, the workflow can send a response message to a source number selected by the user. 
       Syntax 
       [0250]    DIVERT &lt;address&gt;
       &lt;address&gt; is a string paramater representing the mobile number of the redirected address.       
 
       Example 
     DIVERT “+61418366896” 
     MESSAGE Command 
       [0252]    MESSAGE command shows a message with a title and message content to the user. 
       Syntax 
       [0000]    
       
         
           
             MESSAGE &lt;title&gt; &lt;Mesaag cont&gt;
           &lt;title&gt; is a string parameter for of the title of the message to be displayed.   &lt;message content&gt; is a string parameter.   
         
           
         
       
     
         [0256]    The end result is display of a screen as shown in  FIG. 35 . 
       Example 
       [0000]    
       
         
           
             MESSAGE “Hello” “Hello world” 
           
         
       
     
       Response 
       [0258]    This OUT screen does not collect any user input and no response data is associated with it. 
       INPUT Command 
       [0259]    This command displays a GUI screen with a text input box  3602  to the user to retrieve user inputs, as shown in  FIG. 36 . A parameter name is provided in the command to set the name of the user input data when included in the response message. A default input value can be provided as an input parameter. If desired, the user input data can be restricted to a certain types such as numeric, decimal or a phone number. However, the implementation of user input restriction depends on the capability of the user device executing the client application  102 . 
       Syntax 
       [0260]    INPUT&lt;return parameter&gt; &lt;label&gt; &lt;type&gt; &lt;default value&gt;
       &lt;return parameter&gt; is a string parameter for the name of the entered value to be set in the return message.   &lt;label&gt; is the title of the input text box   &lt;type&gt; is the type of the input to be captured, these types are available:
           ANY   EMAILADDR   NUMERIC   PHONENUMBER   URL   DECIMAL   
           &lt;default value&gt; is an optional string parameter to be set to the input text box
           when the screen is visible to the user. If omitted, the default value of the input text box is left empty.   
               
 
       Response 
       [0272]    User input data is included in a response message associated with a parameter name specified in the corresponding instruction. If the INPUT command is executed in a branch routine (sec BRANCH_TO command) then any domain path applicable will be prefixed to the parameter name. 
         [0000]    
       
         
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 &lt;return parameter&gt;=&lt;value&gt; (without domain path) 
               
               
                   
                 &lt;domain path&gt;.&lt;return parameter&gt;=&lt;value&gt; 
               
               
                   
                   
               
             
          
         
       
       
         
           
             Where
           &lt;value&gt; is a string value that user enters. This can be an empty value.   &lt;domain path&gt; is the path of branches that lead to this INPUT command in the workflow.   
         
           
         
       
     
       GAUSS Command 
       [0276]    This command results in the display of an interactive screen having a slider or “gauss” control  3702  to prompt the user to provide corresponding response data, as shown in  FIG. 37 . The user is able to slide the slider control from a minimum value to a maximum value specified on the command line. The resulting data is included in the response message associated with the parameter name given. 
       Syntax 
       [0277]    GAUSS &lt;parameter name&gt; &lt;minimum value&gt; &lt;maximum value&gt; &lt;default value&gt;
       &lt;parameter name&gt; is a string parameter for the name of the gauss value to be set in the return message.   &lt;minimum value&gt; is the minimum value the user can select.   &lt;maximum value&gt; is the maximum value the user can select   &lt;default value&gt; is the default value if the user does not select any value. This parameter is optional so if it is not present, the defanul value is empty.       
 
       Example 
       [0000]    
       
         
           
             GAUSS “temper” “1” “10” “5” 
           
         
       
     
       Response 
       [0283]    If this command is executed in a branch routine (see BRANCH_TO command) then any domain path applicable will be prefixed to the parameter name. 
         [0000]    
       
         
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 &lt;parameter name&gt;=&lt;value&gt; (without domain path) 
               
               
                   
                 &lt;domain path&gt;.&lt;parameter name&gt;=&lt;value&gt; 
               
               
                   
                   
               
             
          
         
       
     
       GOTO Command 
       [0284]    This command allows the workflow execution engine  406  to jump to a specific workflow instruction, rather than proceed to the next instruction in sequence. A parameter of this command is the label of the instruction for the workflow execution to be directed to. There is no user screen or response data associated with this instruction. 
       Syntax 
       [0000]    
       
         
           
             GOTO &lt;label&gt;
           &lt;label&gt; is the label name indicating the index the command that the workflow execution jumps to after executing this command   
         
           
         
       
     
       Example 
       [0287]      
         [0000]    
       
         
               
             
           
               
                   
               
             
             
               
                 .... 
               
               
                 GOTO Hello // The program jumps to message hello world after executing 
               
               
                 this command. 
               
               
                 ... 
               
               
                 ... 
               
               
                 # Hello 
               
               
                 MESSAGE “Hello” “Hello world” 
               
               
                 ... 
               
               
                   
               
             
          
         
       
     
       SELECT SELECT_MULTI Command 
       [0288]    As shown in  FIG. 38 , these commands display a screen with a list of items to select from. The SELECT command allows single item selection, and the SELECT_MULTI command allows multiple item selection screen. The user selection is included in the response message identified by the parameter name. In case of multiple selection list, the selected values are separated by a delimiter character in the response value data. 
       Syntax 
       [0000]    
       
         
           
             SELECT or SELECT_MULTI command is followed by ITEM definitions (one per line). 
           
         
       
     
         [0000]    
       
         
               
               
               
             
               
               
             
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 SELECT 
                 &lt;parameter name&gt; &lt;title&gt; 
               
               
                   
                 ITEM 
                 &lt;item name&gt; 
               
               
                   
                 ITEM 
                 &lt;item name&gt; 
               
               
                   
                 ITEM 
                 &lt;item name&gt; 
               
             
          
           
               
                   
                 SELECT_MULTI&lt; parameter name&gt; &lt;title&gt; 
               
             
          
           
               
                   
                 ITEM 
                 &lt;item name&gt; 
               
               
                   
                 ITEM 
                 &lt;item name&gt; 
               
               
                   
                 ITEM 
                 &lt;item name&gt; 
               
               
                   
                   
               
             
          
         
       
       
         
           
             Where:
           &lt;parameter name&gt; is a string parameter specifying the return parameter id for the SELECT screen.   &lt;title&gt; is a string parameter specifying the title of the screen.   &lt;item name&gt; is a string parameter specifying the item to be displayed on the screen.   
         
           
         
       
     
       Example 
       [0000]    
       
         
           
             // This example allows the mobile user to select one of the option listed 
             SELECT “tsk” “Select task” 
             ITEM “Administration” 
             ITEM “Service desk” 
             ITEM “Client meeting” 
             // This example allows mobile user to select one or many of user names in the list SELECT_MULTI “name” “Select users” 
             ITEM “User 1” 
             ITEM “User 2” 
             ITEM “User 3” 
           
         
       
     
         [0303]    For multiple select command, each of the items in the select list is displayed adjacent to an icon that indicates whether or not the item has been selected by the user. On most mobile devices, a “Mark” button is displayed to allow user to mark the selection of the highlighted item. A “Next” button is also attached to this screen to allow the user to navigate to the next workflow instruction. On some mobile device platforms, the Next button is mapped directly to one of the mobile phone buttons. 
       Response 
       [0000]    
       
         
           
             SELECT command:
           &lt;parameter name&gt;=&lt;item&gt;   
         
             SELECT_MULTI command:
           &lt;parameter name&gt; &lt;item&gt;;&lt;item&gt;;&lt;item&gt;   
         
             Where:
           &lt;Item&gt; is the item name as selectid   
         
             The multiple select response can be empty. 
           
         
       
     
       BRANCH_TO Command 
       [0311]    This command provides users a list of items to select, and on selection of an item, execution of the workflow is branched to the specified command. The behavior of this screen is similar to the SELECT screen described above. Once the workflow execution starts executing from the now target instruction, it follows the default sequential order. When the BRANCH_BACK command is executed, the workflow execution engine returns to the previous BRANCH_TO command to execute. However, the BRANCH_TO command does not require a BRANCH_BACK command to operate. The workflow can consequently branch to the last command without returning to the branch menu. 
         [0312]    To progress to the next screen from a BRANCH_TO command, a “Next” button is provided. On some phones, this button is mapped to one of the phone keys on the mobile device. On most phones however, this button is mapped to a soft-key named “Next” when the user select Options on the BRANCH_TO screen (similar to SELECT_MULTI command). 
         [0313]    There is no specific user value attached to this screen in the response message. The selected branch item is however appended to the branch domain path. This domain path is then appended to the parameter name of any input screens being executed in the branch target. 
       Syntax 
       [0000]    
       
         
           
             BRANCH_TO command is followed by ITEM definitions (one per line). 
           
         
       
     
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 BRANCH_TO 
                 &lt;parameter name&gt; &lt;title&gt; 
               
             
          
           
               
                   
                 ITEM 
                 &lt;item&gt; &lt;label&gt; 
               
               
                   
                 ITEM 
                 &lt;item &gt; &lt;label&gt; 
               
               
                   
                 ITEM 
                 &lt;item &gt; &lt;label&gt; 
               
               
                   
                   
               
             
          
         
       
       
         
           
             Where:
           &lt;parameter name&gt; is a string parameter specifying the return parameter id for the BRANCH_TO screen.   &lt;title&gt; is a string parameter specifying the title of the screen.   &lt;itarm&gt; is a string parameter specifying the item to be displayed on the screen.   &lt;label&gt; is a valid label name as specified in the workflow with “#” character.   
         
           
         
       
     
       Examples 
       [0320]      
         [0000]    
       
         
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 ... 
               
               
                   
                 # EnterBetAmount 
               
               
                   
                 INPUT “bet” “Enter bet amount” DECIMAL 
               
               
                   
                 BRANCH_BACK 
               
               
                   
                 .... 
               
               
                   
                 # SelectBetAmount 
               
               
                   
                 SELECT “bet” “Select bet amount in dollars” 
               
               
                   
                 ITEM “100” 
               
               
                   
                 ITEM “200” 
               
               
                   
                 ITEM “300” 
               
               
                   
                 BRANCH_BACK 
               
               
                   
                 .... 
               
               
                   
                 BRANCH_TO “b” “Select team to bet” 
               
               
                   
                 ITEM “Melbourne” EnterBetAmount 
               
               
                   
                 ITEM “Geelong” SelectBetAmount 
               
               
                   
                 GOTO END 
               
               
                   
                 ... 
               
               
                   
                 # END 
               
               
                   
                 MESSAGE “Info” “Please select Yes to allow response message to 
               
               
                   
                 be sent” 
               
               
                   
                   
               
             
          
         
       
     
       Response 
       [0000]    
       
         
           
             The domain path is appended with &lt;item&gt; selected in the branch menu. 
             This domain path is then appended to the parameter name of any input screen executed in the branch target. In the example script, the “bet” amount parameter name when appearing in the response message is: Melbourne.bet=&lt;bet value&gt;. 
           
         
       
     
       BRANCH_BACK Command 
       [0323]    This command is invisible to the user, it provides the capability to navigate back from branching. A workflow could have multiple branches wired up and the result is a tree like structure. BRANCH_BACK command allows navigation upwards in this tree structure. Combination of label and BRANCH_BACK command, allows combining a group of workflow commands in to a routine, which can be referred to multiple times during the workflow execution. 
       Syntax 
       [0000]    
       
         
           
             BRANCH_BACK 
           
         
       
     
       STORE_PERMANENT Command 
       [0325]    This command instructs the workflow execution to store the whole payload data to persistent storage. A title is set in the parameter of this command allows the client application to display the stored payload data to the user. This command does not result in any user data in the response message. 
       Syntax 
       [0000]    
       
         
           
             STORE_PERMANENT &lt;title&gt; 
             Where:
           &lt;title&gt; is a string parameter indicating the title of workflow payload data to be displayed in the persistent list. This persistent list is displayed to the user when the client application is started manually by the user and no instant payload data is waiting to be executed.   
         
           
         
       
     
       Example 
       [0000]    
       
         
           
             STORE_PERMANENT “Message one” 
           
         
       
     
       CLEAR_PERMANENT Command 
       [0330]    This command clears all the persistent workflow payload data previously saved by STORE_PERMANENT command. Execution of this command does not result in any data in the response message. 
       Syntax 
       [0000]    
       
         
           
             CLEAR_PERMANENT 
           
         
       
     
       EXECUTE Command 
       [0332]    This command makes a request to the mobile device operating system to retrieve an URL address. The results could be making a phone call or launching the internet browser on the phone to the specified URL address. Behavior of this command might varies across different device models due to device capabilities. 
       Syntax 
       [0000]    
       
         
           
             EXECUTE &lt;url_address&gt; 
             Where
           &lt;url_address&gt; is a string parameter describing the URL address of the request to be sent to the J2ME platform.   
         
           
         
       
     
       Example 
       [0336]    To make a mobile phone call to +61418366896 mobile number
       EXECUTE “tel:+61418366896”   To launch the internet browser on the mobile phone to access ACME mobile website EXECUTE “http://mobile.acme.com”       
 
       Response 
       [0339]    If making a mobile phone call is required, the mobile device will ask user if a mobile phone call can be made. If launching of the internet browser is required, the application will ask for the user&#39;s permission to open the internet connection to the specified URL. 
       CONFIGURATION Command 
       [0340]    The response message is constructed from the user/system data. A number of default delimiter characters are used to separate the data parts as well as name-value separator. This command when included in the payload data can change the delimiter characters of the response message as well as specifying whether or not the name part is included in the response message. 
         [0000]    syntax
       CONFIGURATION &lt;configuration_string&gt;       
 
         [0342]    Where &lt;configuration_string&gt; is composed of configuration characters:
       1 st  character: Include parameter in the response, if set to ‘0’, the response message only has values, set to ‘1’, the response message has Name=Value   2 nd  character: Response part delimiter, the default is ‘,’   3 rd  character: Equal character, the default is ‘=’   4 th  character: Multiple selection options, the default is ‘;’   5 th  character: Screen path delimiter, the default is ‘.’       
 
       Example 
       [0000]    
       
         
           
             CONFIGURATION “0,=;.” 
           
         
       
     
         [0349]    This configuration command instructs the workflow execution to exclude parameter names from the response message. 
       SYSTEM_PROPERTY Command 
       [0350]    This command instructs the workflow execution to read a system property and remturn the result in the response. The parameter name that is associated with the response data is the system property if parameter name is omitted. 
       Syntax 
       [0000]    
       
         
           
             SYSTEM_PROPERTY &lt;property_name&gt; &lt;parameter name&gt; 
             Where:
           &lt;property_name&gt; is the system property to be read. On the J2ME platform, examples of these properties are:
               microedition.profiles   microedition.configuration   
               &lt;parameter name&gt; is an optional string parameter. If omitted, property name is used as parameter name in the response instead.   
         
           
         
       
     
       Examples 
       [0000]    
       
         
           
             SYSTEM_PROPERTY “microedition.profiles” 
             SYSTEM_PROPERTY “microedition.profiles” “midp” 
           
         
       
     
       Response 
       [0359]    The value of the system property is included in the response message as name=value pair. All the rules applied to the name-value pairs are applied. These include changing of delimiter parameters and whether or not to include the name part in the response message. 
         [0000]    
       
         
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 &lt;system property&gt;=&lt;value&gt; (if parameter name is omitted) 
               
               
                   
                 &lt;parameter name&gt;=&lt;value&gt; (if parameter name is present) 
               
               
                   
                   
               
             
          
         
       
     
       NOP Command 
       [0360]    This is a no-operation command. It is useful when used in conjunction with labeling. 
       Syntax 
       [0000]    
       
         
           
             NOP 
           
         
       
     
       SET_KEYS Command 
       [0362]    A command to set the encryption key specified by the index of the key on the mobile device. 
       Syntax 
       [0000]    
       
         
           
             SET_KEYS &lt;key_inde&gt; &lt;key&gt; 
           
         
       
     
         [0364]    Where &lt;key_index&gt; is a string parameter indicating the index of the key to be set on the client application  102 . &lt;key&gt; is a string parameter containing the actual key to be updated. 
         [0365]    Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention as hereinbefore described with reference to the accompanying drawings. 
         [0366]    It will be apparent from the description above that the Interactive system and process described herein allow a developer to dynamically send on demand customisable workflow instructions to one or more user devices  106  such as mobile telephones. The generation, secure delivery, execution, and secure return of response data to the developer are all handled transparently by the interactive system, thus hiding all the details of these aspects from the developer, greatly simplifying the provision of interactive applications and quasi-real-time interactions with one or more users. The provision of workflow instructions via SMS is particularly advantageous as it can be assumed to be supported by all mobile telephones available today. Moreover, since the SMS communications are all managed by the interactive system, any premium SMS services that may be required can be established by the operator of the interactive system, thus freeing the developer from needing to establish their own independent premium SMS services. This greatly simplifies the provision of new interactive applications, and also allows the operator of the interactive system to provide these services at a lower cost by leveraging the substantial volume of SMS traffic resulting from the aggregation of SMS traffic or all developers using the interactive system. 
         [0367]    It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.
A method of delivering an instruction ( 206) to a mobile user device ( 106) connected to a network ( 110) is disclosed. The method comprising the steps of receiving an interactive workflow ( 202), translating the interactive workflow into the instruction ( 206) in a form executable by the mobile user device ( 106), and sending a message ( 208) including the instruction ( 206) to the mobile user device ( 106).