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package javax.management;
import java.util.concurrent.CopyOnWriteArrayList; // for Javadoc
/**
* <p>Interface implemented by an MBean that emits Notifications. It
* allows a listener to be registered with the MBean as a notification
* listener.</p>
*
* <h3>Notification dispatch</h3>
*
*<p>When an MBean emits a notification, it considers each listener that has been
* added with {@link #addNotificationListener addNotificationListener} and not
* subsequently removed with {@link #removeNotificationListener removeNotificationListener}.
* If a filter was provided with that listener, and if the filter's
* {@link NotificationFilter#isNotificationEnabled isNotificationEnabled} method returns
* false, the listener is ignored. Otherwise, the listener's
* {@link NotificationListener#handleNotification handleNotification} method is called with
* the notification, as well as the handback object that was provided to
* {@code addNotificationListener}.</p>
*
* <p>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.</p>
*
* <p>Implementations of this interface can differ regarding the thread in which the methods
* of filters and listeners are called.</p>
*
* <p>If the method call of a filter or listener throws an {@link Exception}, then that
* exception should not prevent other listeners from being invoked. However, if the method
* call throws an {@link Error}, then it is recommended that processing of the notification
* stop at that point, and if it is possible to propagate the {@code Error} to the sender of
* the notification, this should be done.</p>
*
* <p>This interface should be used by new code in preference to the
* {@link NotificationBroadcaster} interface.</p>
*
* <p>Implementations of this interface and of {@code NotificationBroadcaster}
* 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 {@link CopyOnWriteArrayList} for this list.
*
* @since 1.5
*/
public interface NotificationEmitter extends NotificationBroadcaster {
/**
* <p>Removes a listener from this MBean. The MBean must have a
* listener that exactly matches the given <code>listener</code>,
* <code>filter</code>, and <code>handback</code> parameters. If
* there is more than one such listener, only one is removed.</p>
*
* <p>The <code>filter</code> and <code>handback</code> parameters
* may be null if and only if they are null in a listener to be
* removed.</p>
*
* @param listener A listener that was previously added to this
* MBean.
* @param filter The filter that was specified when the listener
* was added.
* @param handback The handback that was specified when the listener was
* added.
*
* @exception ListenerNotFoundException The listener is not
* registered with the MBean, or it is not registered with the
* given filter and handback.
*/
public void removeNotificationListener(NotificationListener listener,
NotificationFilter filter,
Object handback)
throws ListenerNotFoundException;
}