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Adding an onEvent Event Handler

The

onEvent

element indicates that the event specified waits for a message to arrive. This element is very similar to a receive activity, except that a message event cannot create a new process instance. Also, an

onEvent

must contain a scope activity and optionally uses a variable local to the event handler that contains the message received from a partner.

An incoming message can correspond to a request/response or one-way operation in a WSDL. When the operation is a request/response type, the event handler is expected to use a reply to send back the response.

Required Properties	Optional Properties
Participant	Variable
Operation	Port Type
	Correlations. See Correlation
	Comment. See Adding Comments to a Process
	Documentation. See Adding Documentation to a Process
	See Setting Visual Properties and Using Your Own Library of Images.
	Execution State. See Viewing the Execution State of an Activity or Link
	Message Exchange. See Message Exchange Declaration
	Extension Attributes and Extension Elements. See Declaring Extension Elements and Attributes.

To add an onEvent event handler for the process:

Ensure that you have added a participant for the event handler before you can complete the properties for it.

Click on the Event Handlers tab of the Process Editor.

Drag a Message catch event
to the Event Handlers canvas.

From the Properties view, select a participant, operation, and optionally select a Variable Definition and type in a Variable name. This variable is an implicit scope variable that can be used by other activities.

Drag an activity into the

onEven

t's scope to respond to the event, such as a reply or exit.

Fill in the properties for the activity that handles the event.

The following illustration shows an example of an onEvent event handler added for the process. If you collapse the event handler, you can add a background color in the Properties view.

To add an onEvent event handler for a scope:

Ensure that you have added a WSDL file to Project Explorer containing the participant information needed.

Display a BPEL file in the Process Editor, and select a scope.

Drag a Message catch event
to the scope.

Fill in the properties of the

onEvent

, including the participant, operation and optionally type in a variable. This variable is an implicit scope variable that can be used by other activities.

Drag an activity into the

onEven

t's scope to respond to the event, such as a reply or exit.

Fill in the properties for the activity that handles the event.

The following illustration shows an example of an

onEvent

and an

onAlarm

event handler added for a scope. The activity responding to each event is a reply.