5.8. Notifying Clients with Events

An event is raised (or sent) by a publisher (or sender) when something of interest occurs (such as an action taking place, or a property changing). Clients can subscribe to the event by providing a suitable delegate, rather like the callbacks we used previously. The method wrapped by the delegate is called the event handler. The neat thing is that more than one client can subscribe to the event.

Here’s an example of a couple of events that we can add to the DocumentProcessor to help our production team: