Java Programmer's Guide and Reference

Observers

The JTAPI model uses the following Observer objects for event notification. The application must provide an implementation that uses the appropriate xxxxxChangedEvent() method.

Provider Observer

Associated only with Providers. This interface reports all state changes of the Provider object.

Call Observer

Associated with Calls, but can be added to Addresses and Terminals for event notification when those objects are part of a Call. Receives Call events.

Address Observer

Associated only with Addresses. This interface reports all state changes of the Address object.

Terminal Observer

Associated only with Terminals. This interface reports all state changes of the Terminal object.

The following information is useful in understanding events sent to Observers:

• When an Observer is first added to an object, information about the initial state of the object is recorded and sent as an event (with a cause of CAUSE_SNAPSHOT) to the Observer.
• Events sent to the Observers represent the state of an object at the time the event was created; the events may not necessarily reflect the current state of the object.
• The types of events that Observers receive depend on what the Observers implement. For example, a CallObserver that implements the core CallObserver and the CallControlCallObserver will receive both core Call Events and CallControlCall Events.

Note:

The implementation of the IBM CallPath Enterprise Toolkit for Java uses multiple threads; one thread is used to send events to all Observers. To ensure that events flow in a timely manner, write Observer implementations that minimize the processing time within the xxxxxChangedEvent() method. For more information, see JTAPI example.

For more information about Observers, refer to the JavaSoft JTAPI 1.2 documentation.