A CompositeActivity manages the execution of its child activities using ActivityExecutionContext class methods and events defined on the Activity class. For example, a child activity is scheduled for execution using the ExecuteActivity of ActivityExecutionContext. A CompositeActivity activity can be notified when a child activity completes its execution by subscribing to the Closed event defined on Activity.

The workflow runtime enforces certain constraints on CompositeActivity execution, the most fundamental of which is that a CompositeActivity activity cannot move to the Closed state if any child activities are still in a Executing, Canceling, Compensating, or Faulting, state.