Invoking an external implementation by using a user task

You can use an external service that has an external implementation when you want a user task to be implemented by an application outside of IBM® Business Automation Workflow. For example, you created your own user interface for your users that you would prefer to use. So you create an external service that has an external implementation to call your own interface. You could also use a system task to call an external implementation; however, this use of system tasks is deprecated, so use a user task instead.

To create an external implementation:

1. In the library navigation, click the + for Services and select External Service.
2. Select External Implementation and click Next.
3. Enter a name for your service and then click Finish.
4. A basic external service that has an external implementation is created with no operations. You should create at least one operation. If your external implementation provides an interface in which a manager can either approve or reject an expense report, you might further revise the operation. You might include input parameters for the expense report data and output parameters for the decision that the manager makes and the justification for the decision. The input and output parameters define the dynamic data for the operation. These parameters would be different for each process instance or environment. You can't add faults.

   In the Details section, the name is shown and you can add a description.

5. If you select Binding for an operation, you see that your service has an External implementation binding type. If you select an operation, you see sections for the properties used in creating an external implementation of an operation. The sections are as follows:
   • URL Template (Required for Process Portal): Add the URL to the external implementation you want to use. When a user opens a task in Process Portal, the URL template is used to call the appropriate external implementation. To include runtime information, such as the task local and environment context, use replacement variables that are surrounded by curly brackets in the URL Template text. Process Portal automatically appends the REST URL to the restUrlPrefix parameter to indicate where task related operations can be performed.
     Tip: To ensure that the external implementation can identify the current task, it is a good idea to include the task ID in the URL template. For example,

     /MyExternalApp/ExternalImpl.jsp?taskId={tw.system.task_id}&lastName={tw.local.lastName}

   • Ajax Services: Select Authorize Ajax services and select the services in Business Automation Workflow that you want to allow the external implementation to use. Clearing the check box disables the runtime authorization check, which means any Ajax service in Business Automation Workflow can be used by the external implementation.
   • Custom Properties: Add the properties in name-value pairs to identify and run the external implementation. These properties are static configuration values to be queried by the external implementation. For example, you might add the external application name or system ID to find the implementation. You can add properties with special meaning. For example, the name url might be used with a value for the actual URL such as http://mysite.com ....
6. Implement all the operations for your service.
7. Click Save or Finish Editing.