/*

 * Copyright 1999-2005 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

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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>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();

}