Interface NotificationBroadcaster

Interface implemented by an MBean that emits Notifications. It allows a listener to be registered with the MBean as a notification listener.

Notification dispatch

When an MBean emits a notification, it considers each listener that has been added with addNotificationListener and not subsequently removed with removeNotificationListener. If a filter was provided with that listener, and if the filter's isNotificationEnabled method returns false, the listener is ignored. Otherwise, the listener's handleNotification method is called with the notification, as well as the handback object that was provided to addNotificationListener.

If the same listener is added more than once, it is considered as many times as it was added. It is often useful to add the same listener with different filters or handback objects.

Implementations of this interface can differ regarding the thread in which the methods of filters and listeners are called.

If the method call of a filter or listener throws an Exception, then that exception should not prevent other listeners from being invoked. However, if the method call throws an Error, then it is recommended that processing of the notification stop at that point, and if it is possible to propagate the Error to the sender of the notification, this should be done.

New code should use the NotificationEmitter interface instead.

Implementations of this interface and of NotificationEmitter should be careful about synchronization. In particular, it is not a good idea for an implementation to hold any locks while it is calling a listener. To deal with the possibility that the list of listeners might change while a notification is being dispatched, a good strategy is to use a CopyOnWriteArrayList for this list.

Methods

addNotificationListener

void addNotificationListener(NotificationListener listener,
                             NotificationFilter filter,
                             Object handback)
                      throws IllegalArgumentException

Adds a listener to this MBean.

Parameters:

listener - The listener object which will handle the notifications emitted by the broadcaster.

filter - The filter object. If filter is null, no filtering will be performed before handling notifications.

handback - An opaque object to be sent back to the listener when a notification is emitted. This object cannot be used by the Notification broadcaster object. It should be resent unchanged with the notification to the listener.

Throws:

IllegalArgumentException - Listener parameter is null.

See Also:

removeNotificationListener(javax.management.NotificationListener)

removeNotificationListener

void removeNotificationListener(NotificationListener listener)
                         throws ListenerNotFoundException

Removes a listener from this MBean. If the listener has been registered with different handback objects or notification filters, all entries corresponding to the listener will be removed.

Parameters:

listener - A listener that was previously added to this MBean.

Throws:

ListenerNotFoundException - The listener is not registered with the MBean.

See Also:

addNotificationListener(javax.management.NotificationListener, javax.management.NotificationFilter, java.lang.Object), NotificationEmitter.removeNotificationListener(javax.management.NotificationListener, javax.management.NotificationFilter, java.lang.Object)

getNotificationInfo

MBeanNotificationInfo[] getNotificationInfo()

Returns:

the array of possible notifications.