The interface definition for a PureMVC Notification.

PureMVC does not rely upon underlying event models such as the one provided with Flash.

The Observer Pattern as implemented within PureMVC exists to support event-driven communication between the application and the actors of the MVC triad.

Notifications are not meant to be a replacement for Events. Generally, IMediator implementors place event listeners on their view components, which they then handle in the usual way. This may lead to the broadcast of Notifications to trigger ICommands or to communicate with other IMediators. IProxy and ICommand instances communicate with each other and IMediators by broadcasting INotifications.

A key difference between Flash Events and PureMVC Notifications is that Events follow the 'Chain of Responsibility' pattern, 'bubbling' up the display hierarchy until some parent component handles the Event, while PureMVC Notifications follow a 'Publish/Subscribe' pattern. PureMVC classes need not be related to each other in a parent/child relationship in order to communicate with one another using Notifications.