/* * Copyright (c) 1999, 2005, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */  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>New code should use the {@link NotificationEmitter} interface * instead.</p> * * <p>Implementations of this interface and of {@code 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 {@link CopyOnWriteArrayList} for this list. * * @since 1.5 */public interface NotificationBroadcaster {     /**     * Adds a listener to this MBean.     *     * @param listener The listener object which will handle the     * notifications emitted by the broadcaster.     * @param filter The filter object. If filter is null, no     * filtering will be performed before handling notifications.     * @param 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.     *     * @exception IllegalArgumentException Listener parameter is null.     *     * @see #removeNotificationListener     */    public void addNotificationListener(NotificationListener listener,                                        NotificationFilter filter,                                        Object handback)            throws java.lang.IllegalArgumentException;     /**     * 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.     *     * @param listener A listener that was previously added to this     * MBean.     *     * @exception ListenerNotFoundException The listener is not     * registered with the MBean.     *     * @see #addNotificationListener     * @see NotificationEmitter#removeNotificationListener     */    public void removeNotificationListener(NotificationListener listener)            throws ListenerNotFoundException;     /**     * <p>Returns an array indicating, for each notification this     * MBean may send, the name of the Java class of the notification     * and the notification type.</p>     *     * <p>It is not illegal for the MBean to send notifications not     * described in this array.  However, some clients of the MBean     * server may depend on the array being complete for their correct     * functioning.</p>     *     * @return the array of possible notifications.     */    public MBeanNotificationInfo[] getNotificationInfo();}