Create an external implementation in the Designer view
when you want to reuse an existing external application or create
an external application to handle one or more steps in your process.
About this task
Using the external implementation function is similar
to using the service functions like the integration service or web
service. However, unlike those service functions that are designed
for a specific area like web services or integration, the external
implementation is more generic in nature. When a step in a business
process is implemented with an external implementation, the business
process halts and waits for input from the external application.
To
create an external implementation, use the Web APIs or REST APIs.
The previous topic discusses a sample that creates an external implementation
with the Web APIs. To create an external implementation with the REST
APIs, these articles are helpful. 
Using the REST APIs in IBM Business Process Manager and 
Integrating a business process application with an
external system using the REST API. The related links at the
bottom of this topic link to more information on the Web APIs and
REST APIs.
When you create an external implementation in
the Designer view in IBM® Process Designer,
you need to know the properties to use to identify and execute the
custom application. If you did not build the custom application, you
need to coordinate with the developers to ensure that you provide
the appropriate properties in IBM Process Designer.
- In the Designer view, click the plus sign next to Implementation and
select External Implementation from the list
of components.
- Supply a descriptive name for the new external implementation.
- Click Finish.
- In the Common section of the External Implementation dialog,
optionally provide a description in the Documentation text box.
- In the Custom Properties section, specify the properties
to identify and run the external application.
For example,
for an external Eclipse RCP application, you might add custom properties
to pass the Java Class name of the form to use for an activity or
an application-specific identifier to look up the implementation by
another means. Alternatively, you might use the external application
name or system ID to find the implementation.
You can create
parameters with a special meaning. For example, suppose you need to
pass a URL address as a custom property? In the Custom Properties
section you could use url as the name and then
add a value that is the URL itself (http://mysite.com...).
You
can also use this section to pass data to variables in a client that
were instantiated with a constructor.
Note: You can
add custom properties to pass static metadata about the implemenation
to the external application. For dynamic data, which would be different
for each process instance or environment, use the Parameter Details
section of the dialog as outlined in the following step.
- In the Parameters section of the dialog, add the parameters
for the external implementation by clicking Add Input or Add
Output.
For example, if the external implementation
provides an interface in which a manager can either approve or reject
an expense report, it might include input parameters for the expense
report data and output parameters for the decision that the manager
makes and the justification for his decision.
Be
sure to account for all process data that the external implementation
requires to complete successfully and also for any data required from
the external activity by subsequent activities.
- Click Save in the main toolbar.
What to do next
You can use an external implementation with Process Portal.
In the Custom Properties section add the URL for Process Portal as
shown earlier. In the article, Load External Activity URLs from Teamworks Portal,
you will see how to retrieve a task ID from the business process to
work with a specific task.