IBM BPM, V8.0.1, All platforms > Authoring services in Integration Designer > Developing business processes > Building BPEL processes > Defining BPEL process logic > Adding an activity to a BPEL process

Work with structured activities

A structured activity contains one or more other activities that are arranged on one or more separate paths. Here are some tips on how to work with these activities in the editor.

Here is a list of the structured activities that are relevant to this topic:

Choice activity

This activity evaluates the conditions on two or more control paths and follows the appropriate one. It can contain case and otherwise elements.

• Case element

• Used within a choice activity, this element is used to create a control path and define the conditions that will cause this path to run. When run, the process will evaluate the conditions in each of the case elements, and follow the first one that evaluates to true.

• Otherwise element

• Use this element within a choice activity to create a control path that will run when none of the other cases evaluate to true. Use this element on only one of the paths within a choice activity. When run, the process will evaluate the conditions in each of the case elements, and should none of them evaluate to true, it will run the activities in this path.

Generalized flow activity

Use this activities to nest activities on individual, customized control paths. This activity is equivalent to the concept of split/merge: although there are multiple paths within the activity, only the path that evaluates to true will be followed, and the target activity will start the moment that path has completed.

• Link

• Use the link within a Generalized flow activity to connect nested activities and form individual control paths. The link is used to express a synchronization dependency. In other words, it runs under a constraint because the link creates a dependency of one activity and the variables it uses on another activity. You can specify a transition condition on the link in the properties area of the BPEL process editor.

For Each activity

The For Each activity repeatedly runs the activities that it contains either sequentially or in parallel for a specified number of iterations.

The related link For Each activity - a typical usage pattern provides excellent information on getting started with For Each activities.

For an example of how to use an assign activity to iterate an array in a For Each activity, see Use assign.

Parallel activity

Use this activity to nest other activities that will run concurrently. A link is used to connect the activities that it contains. This activity is equivalent to the concept of fork/join: all the paths within the activity are run simultaneously, and the target activity will not fire until all paths have completed.

• Link

• Use the link within a parallel activity to connect nested activities and form individual control paths. The link is used to express a synchronization dependency. In other words, it runs under a constraint because the link creates a dependency of one activity and the variables it uses on another activity. You can specify a transition condition on the link in the properties area of the BPEL process editor.

Scope activity

Use this to act as a behavioral container for one or more activities in your process.

You can also use a scope activity for enhanced dynamic behavior, by using an administrative human task to grant a user administrative privileges over the running order of the activities that are nested within the scope. Enhanced dynamic behavior is more fully supported by using a Collaboration Scope. See related topics for more information.

Sequence activity

Use this to nest a series of activities into your process that will run sequentially.

While loop activity

Use this activity to repeat one or more activities as long as specific conditions are in place. The conditions are evaluated at the beginning of the activity. Hence the activity is skipped if the condition is not met on entry.

Repeat until loop activity

Use this activity to repeat one or more activities as long as specific conditions are in place. The conditions are evaluated at the end of the activity. Hence the activity is performed at least once.

To work with a structured activity, proceed as follows:

Procedure

1. Choose a structured activity from palette, and drop it to the canvas. The activity will appear with a distinct rectangular workspace.

   • If this is a choice or a receive choice activity, it will contain a default element representing a single control path.
   • With the exception of the parallel and generalized flow activities, all structured activities differentiate the activities that they contain into separate control paths. In parallel or generalized flow activities, you create the control path yourself with links.

2. Populate the workspace with activities from the palette. If this is the first activity that you're dropping to the workspace, it will automatically appear in the first path. If there are already activities on the path, then a black line will appear as you hover over the path showing where you can drop the new activity.

3. To create a new path in the structured activity (only some structured activities support multiple paths), hover over the activity's icon until the action bar appears, and select an element from it.

4. You can expand or collapse this structured activity in either one of the two following ways:

   1. Click the plus () or minus () icons as appropriate.
   2. Double-click the structured activity.

• Linking activities within parallel and generalized flow activities
  Links direct the sequence in which the execution of activities occurs within parallel and generalized flow activities.
• Work with parallel activities
  A parallel process (or flow) is a collection of other process activities that are all nested within a parallel activity. The nested activities run sequentially in an order that is dictated by links and transition conditions (when no links are present, all activities will be executed concurrently). When activities are arranged on separate control paths, the paths will run concurrently.
• Work with generalized flow activities
  The generalized flow activity is very similar to a parallel activity in that you can nest other process activities within it, and then control the execution order of those activities through links. The generalized flow activity differs however in its ability to use conditional links to loop back to previous activities in the sequence.
• Enhanced dynamic behavior in a process
  

  You can configure a scope activity so that users interacting with a runtime instance of the process will have administrative authority over the activities that are nested within the scope activity. You can achieve enhanced dynamic behavior more directly using a "collaboration scope" in which the associated administration task is automatically generated when the collaboration scope is added to the BPEL process.

• Modify the join behavior of an activity
  Instructions on how to change the behavior of an activity's input link.

Adding an activity to a BPEL process

Building BPEL processes

Related concepts:
Replacement variables and context variables
Use Java methods in process snippets
Use custom properties for human tasks
Use event handlers
Cases

Related tasks:
Modify the properties of an activity
Modify the type of an activity
Work with basic activities
Modeling human workflows
Linking activities within parallel and generalized flow activities
Work with parallel activities

Related information:

For Each activity - a typical usage pattern