01 /*
02 * Copyright 2002-2007 Sun Microsystems, Inc. All Rights Reserved.
03 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
04 *
05 * This code is free software; you can redistribute it and/or modify it
06 * under the terms of the GNU General Public License version 2 only, as
07 * published by the Free Software Foundation. Sun designates this
08 * particular file as subject to the "Classpath" exception as provided
09 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package javax.management;
27
28 import java.util.concurrent.CopyOnWriteArrayList; // for Javadoc
29
30 /**
31 * <p>Interface implemented by an MBean that emits Notifications. It
32 * allows a listener to be registered with the MBean as a notification
33 * listener.</p>
34 *
35 * <h3>Notification dispatch</h3>
36 *
37 *<p>When an MBean emits a notification, it considers each listener that has been
38 * added with {@link #addNotificationListener addNotificationListener} and not
39 * subsequently removed with {@link #removeNotificationListener removeNotificationListener}.
40 * If a filter was provided with that listener, and if the filter's
41 * {@link NotificationFilter#isNotificationEnabled isNotificationEnabled} method returns
42 * false, the listener is ignored. Otherwise, the listener's
43 * {@link NotificationListener#handleNotification handleNotification} method is called with
44 * the notification, as well as the handback object that was provided to
45 * {@code addNotificationListener}.</p>
46 *
47 * <p>If the same listener is added more than once, it is considered as many times as it was
48 * added. It is often useful to add the same listener with different filters or handback
49 * objects.</p>
50 *
51 * <p>Implementations of this interface can differ regarding the thread in which the methods
52 * of filters and listeners are called.</p>
53 *
54 * <p>If the method call of a filter or listener throws an {@link Exception}, then that
55 * exception should not prevent other listeners from being invoked. However, if the method
56 * call throws an {@link Error}, then it is recommended that processing of the notification
57 * stop at that point, and if it is possible to propagate the {@code Error} to the sender of
58 * the notification, this should be done.</p>
59 *
60 * <p>This interface should be used by new code in preference to the
61 * {@link NotificationBroadcaster} interface.</p>
62 *
63 * <p>Implementations of this interface and of {@code NotificationBroadcaster}
64 * should be careful about synchronization. In particular, it is not a good
65 * idea for an implementation to hold any locks while it is calling a
66 * listener. To deal with the possibility that the list of listeners might
67 * change while a notification is being dispatched, a good strategy is to
68 * use a {@link CopyOnWriteArrayList} for this list.
69 *
70 * @since 1.5
71 */
72 public interface NotificationEmitter extends NotificationBroadcaster {
73 /**
74 * <p>Removes a listener from this MBean. The MBean must have a
75 * listener that exactly matches the given <code>listener</code>,
76 * <code>filter</code>, and <code>handback</code> parameters. If
77 * there is more than one such listener, only one is removed.</p>
78 *
79 * <p>The <code>filter</code> and <code>handback</code> parameters
80 * may be null if and only if they are null in a listener to be
81 * removed.</p>
82 *
83 * @param listener A listener that was previously added to this
84 * MBean.
85 * @param filter The filter that was specified when the listener
86 * was added.
87 * @param handback The handback that was specified when the listener was
88 * added.
89 *
90 * @exception ListenerNotFoundException The listener is not
91 * registered with the MBean, or it is not registered with the
92 * given filter and handback.
93 */
94 public void removeNotificationListener(
95 NotificationListener listener, NotificationFilter filter,
96 Object handback) throws ListenerNotFoundException;
97 }
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