After the Relay cache applies an update to a cached object it notifies its client application of the change. The cache uses the java.util.Observer interface to notify the client application.
Client applications must implement the java.util.Observer interface. This interface consists of one method, update(Observable o, Object obj). The Relay cache makes an upcall to this method every time an update is applied to cached data.
Table 4.1 summarizes the interaction between client applications, cached objects, and the Relay System. Figure 4.2 depicts the flow of an update through the Relay system.
Table 4.1: Summary of methods called by client applications and Relay system.
Figure 4.2: Flow of an update through the Relay system