Sep 22, 2008

EventHandlingScopeActivity

The EventHandlingScopeActivity is a dramatically different type of event handling activity. It has two discrete sections: a main line child activity and a set of event handling activities. The single main line child activity executes in a normal manner. When the main line activity completes, the entire EventHandlingScopeActivity comes to an end. In addition to the main line child activity, event handling activites are contained within a single EventHandlersActivity that is a child of EventHandlingScopeActivity. The EventHandlerActivity is the parent for one or more EventDrivenActivity instances, with each one activing as a seperate branch of execution. Each EventDrivenActivity contains one or more child activities, but the first child must implement IEventActivity(e.g. HandlingExternalEventActivity) in order to start execution of the branch. When an event is received, the activites within EventDrivenActivty are executed. However, unlike the more common event handling of ListenActivity, the order event branch are all still alive. They can also receive their events and execute the activities within their execution branch. The orginal branch that recived its event cal even receive it again.

These activities are used in advanced scenarios where you need to concurrently handle multiple events and execute a main line set of activities at the same time. In the example that follows, you will implement a workflow using the EventHandlingScopeActivity. It contains a main line set of activities that execute while a condition is true. It also handles three external events, one of which is being used to set the condition for the main line activities.