Problem – Describing Mutual Dependencies and Synchronization between Entities
An action may be blocked from being performed until two or more events occur. These may be simultaneous events or events that place the entity or entities in a satisfactory state.
Solution
Event management may be defined in terms of a stimulus-response or event-condition-action structure to capture initiating or prevention action logic. Since the Event Management pattern is defined as a mutual dependency, the participation of two or more entities is often present. Since events are the focus, temporal aspects are also present. The distinction of mutual dependency and synchronization types refers to the existence of events occurring in any sequence versus the simultaneous occurrence of events.
Example – Initiating Benefit Payment The administrator for a pension trust fund is not authorized to commence payments until an election has been made and confirmation is received that the employee has terminated employment.
| Event Management Type | mutual dependency |
| Events | {termination confirmation, benefit election} |
UML Representation and Related Patterns
The Event Management pattern has an affinity with both the Temporal Association and Entity Association patterns. It differs from both of these primarily in the focus of the rule specification, which is event based rather than state based.