Modeling event subprocesses

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Event subprocesses are triggered by an event that occurs in the parent process. Event subprocesses are similar to other subprocesses in that they are contained within a parent process, and are not reusable outside of that process. They are unlike other subprocesses in that they are not connected to other activities in the process by incoming or outgoing connections, but are instead triggered by an event or timer.

About this task

The event subprocess is a specialized subprocess that you can use to model event-handling logic for a process or subprocess. It is triggered upon occurrence of a configured start event, and as a result it is not connected to other steps through sequence flow. It has access to the business objects (variables) of its parent process and so can encapsulate steps that use those variables. When triggered, an event subprocess can either interrupt the execution of its parent or it can run in parallel.

You can use event subprocesses to handle exceptional process flows within your process. For example, an event subprocess can be used to handle an out-of-stock situation that arises during an order-fulfilment process. The out-of-stock event in the parent process triggers the start event in the event subprocess, which contains activities to order more stock or to check supplies at other locations.

An event subprocess can have only one start event. The start event implementation is represented visually in the event subprocess activity in the parent process. It can have any of the following implementation types:

Table 1. Event subprocess implementation types and visualizations
Start event implementation type	Event subprocess visualization
Error
UCA Message
SCA Message
ECM Content
Timer

Message event subprocesses are triggered by a message event that often originates from outside the process in which the event subprocess is contained. A message start event might be used in a situation similar to the situation described previously, where a message, such as an out-of-stock message, is received by the event subprocess and triggers a sequence of activities.
A timer start event might be used to model the steps to take when an activity within the parent process is not completed after a specified amount of time. For example if a requested item cannot be located within a certain amount of time, the out-of-stock subprocess can be triggered by a timer start event.
An error start event might be triggered when something goes wrong in the process, for example, the order fulfilment system is non-responsive. Error start events can be triggered only from within the parent process or its subprocesses.

A parent process cannot complete until all active event subprocesses are complete, unless the parent is terminated by a terminate end event. A terminate end event in an event subprocess terminates only the activities that are contained within that event subprocess.

Boundary events cannot be attached to event subprocesses. To handle exceptions within an event subprocess, for example, errors that arise during the event subprocess execution, event subprocesses can themselves contain event subprocesses.

To add an event subprocess to your process:

Procedure

Open the parent process in the designer.
Drag an event subprocess from the palette onto the diagram area. By default, new event subprocesses are assigned an error start event.
To change the start event type and properties and to add activities to the event subprocess, double-click the event subprocess activity to expand it.
Select the start event and, from the General tab in the properties view, select a new implementation type from the list.
The start events for event subprocesses can be interrupting or non-interrupting. When triggered, event subprocesses with an interrupting start event terminate all activities in the parent process. Activities in an event subprocess with a non-interrupting start event run in parallel with the parent process. You can specify whether the start event of the event subprocess is interrupting or non-interrupting by selecting or by clearing Interrupt Parent Process.

Note: Error start events in an event subprocess always interrupt the parent process and cannot be set to non-interrupting.
To configure an event subprocess to be repeatable, select Repeatable on the General tab. When you select this property, the event subprocess might run several times during the execution of a process, and might have multiple instances that run in parallel.

Note: Unlike subprocesses, looping behavior is not supported for event subprocesses.
Drag elements from the palette onto the canvas.
The names of the activities that you create in your subprocess must be different from the names of the activities in the top-level process or any other subprocess or event subprocess under the same top-level process.

Any swimlanes or phases that you add to your subprocess are independent from the swimlanes and phases that are contained in the parent process.
Like subprocesses, event subprocesses have access to the data of the parent process. Data mapping is not required to pass data into or out of the event subprocess. You can also declare private variables within the event subprocess itself, which are not visible to the parent process. See Modeling subprocess data.
Click Save or Finish Editing.

What to do next

To return to the parent process, use the navigation in the upper left of the canvas.