Events

There are three types of events in terms of how they affect the flow: start, intermediate, and end. Events also have different triggers that initiate them, and can be modeled either separately on the diagram, or as a function of a Sequence Flow line.

The Start Event indicates where a particular process will start. A start event is displayed as a simple circle. When you place an event on a BPMN diagram for the first time, by default the event is represented as an Intermediate Event.

A Start event has a Trigger that defines the cause for the event. You can select the type of trigger for an event in its Trigger Type property. An event's notation is dependant on the trigger type.

Intermediate Events occur between a Start Event and an End Event. An intermediate event is an event that occurs after a Process has been started. It affects the flow of the process, but does not start or directly terminate the process. An intermediate event is displayed as a circle with a double band.

An Intermediate event has a Trigger that defines the cause for the event. You can select the type of trigger for an event in its Trigger Type property. An event’s notation is dependant on the trigger type.

End Events indicate where a particular process will end. An end event is displayed with a thick, bold circle boundary.

You can also model different trigger types of events on a BPMN diagram, such as a simple event, a message, a timer event, a rule event, a link event, a multiple event, a process error, and a compensation event. The toolbar enables you to choose any of these event types and draw them on a diagram.

See the BPMN specification for details about trigger types and the appearance of modeling elements.

A process can be interrupted by an event. You model this by specifying that the Event Boundary Behavior property of a Sequence Flow is set to Interrupting. This is the default value, since an event normally does affect the process flow.

You can set event properties in the Sequence Flow line definition dialog box when the line is associated with an event.

You can specify that the Event definition is part of a Category. A category is a simple grouping mechanism, introduced by the BPMN 1.0 specification. Assigning an Event to a Category enables you to show a hierarchy of categories and the Events that belong to them using a System Architect Decomposition diagram.

The properties presented for an event are based on the trigger type (specified in the Introduction tab, and applied by pressing the Apply button). The mapping of the event to BPEL4WS is also specific to the Trigger Type setting, as specified below.

Available if you specify the Trigger Type property of the Event (on the Introduction tab) as Compensation, and clicked the Apply button. You can type in the compensation in the Compensation field. This will map to a compensate element in BPEL. The Name of the activity referenced by the Compensation Event will map to the scope attribute of the compensate element.

Available if you specify the Trigger Type property of the Event (on the Introduction tab) as Exception, and click the Apply button. This page provides fields for you specify information about the exception.

Available if you specify the Trigger Type property of the Event (on the Introduction tab) as Link, and click the Apply button. Click Choices to drag BPMN events that are linked to this event.

If the Trigger is a Message, then a Message must be supplied. You can specify the message name, properties (0-N), and from and to participants (pools or lanes). A property has a name, type, and condition.

Available if you have specified the Trigger Type property of the Event (on the Introduction tab) as Multiple, and pressed the Apply button. This page provides properties you can use to define the Multiple Event.

If you specify None as the Trigger Type, the event will not map to any BPEL element. The objects that are the Targets of the Sequence Flow that originate from the Start Event will determine the first BPEL4WS element of the Process.

Available if you specify the Trigger Type property of the Event (on the Introduction tab) as Rule, and click the Apply button. This page provides the Rule field.

Available if you specify the Trigger Type property of the Event (on the Introduction tab) as Timer, and click the Apply button.

In the Timer field, you can type in the Timer expression. If the event of type Timer is found within the normal flow of a Business Process diagram, it maps to a wait in the generated BPEL.

Available if you specify the Trigger Type property of the Event (on the Introduction tab) as Timer, and click the Apply button.

Timer Date: You can type in the Timer expression in the text field. The Timer Date attribute maps to the until attribute of the wait.

Time Cycle: You can type in the Timer expression in the text field. The Time Cycle attribute maps to the for attribute of the wait.