It is often useful for a NameContext to fire an event whenever an element is bound or unbound from that NameContext. For example, a pricing component may wish to be notified whenever an element is bound into a shopping cart component.
A NameContext declares that it fires such events by implementing NameContextBindingEventSource. This declares that NameContextBindingListeners may be added to the NameContext. These listeners will receive notifications whenever elements are bound or unbound from the NameContext.
If a component declares that it implements NameContextBindingEventSource, that component is also expected to perform the following behavior: whenever an element is bound or unbound from the NameContext, the NameContext should check to see if that element implements NameContextBindingListener. If it does, then the NameContext should send a bound or unbound event to that element. This behavior must be performed in addition to notifying the registered listeners.
A sample implementation of this behavior can be found in the source code for atg.naming.NameContextImpl, found in the <ATG2007.3dir>/DAS/src/Java/atg/naming directory. This class implements all of the following interfaces:
atg.naming.NameContextBindingEventSource, which extendsatg.naming.NameContext, which extendsatg.naming.NameContextElement, which extendsatg.naming.NameContextBindingListener
If your component implements NameContext, then you might consider implementing NameContextBindingEventSource as well. This is usually only required if arbitrary elements are going to be bound and unbound from your NameContext, which is usually not the case for an application-specific component. For example, the last example of the previous section implemented a read-only NameContext, and implementing NameContextBindingEventSource on that object would not be very useful.
