4ca1e4ba_Pattern_for_Event_Notification_son_with_Mediator_and_Observer_Event_Notifier
[0] Messaging flexibility [Mediator] Application-specific messages through methods defined at compile time [Observer] Single generic message through the predefined update() method [Event Notifier] 
Flexible messaging by using different event types
Event Notifier, a Pattern for Event Notification
Event Notifier