1 /*
2 * Copyright 1999-2005 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * 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
27 package javax.management;
28
29 import java.util.concurrent.CopyOnWriteArrayList; // for Javadoc
30
31 /**
32 * <p>Interface implemented by an MBean that emits Notifications. It
33 * allows a listener to be registered with the MBean as a notification
34 * listener.</p>
35 *
36 * <h3>Notification dispatch</h3>
37 *
38 * <p>When an MBean emits a notification, it considers each listener that has been
39 * added with {@link #addNotificationListener addNotificationListener} and not
40 * subsequently removed with {@link #removeNotificationListener removeNotificationListener}.
41 * If a filter was provided with that listener, and if the filter's
42 * {@link NotificationFilter#isNotificationEnabled isNotificationEnabled} method returns
43 * false, the listener is ignored. Otherwise, the listener's
44 * {@link NotificationListener#handleNotification handleNotification} method is called with
45 * the notification, as well as the handback object that was provided to
46 * {@code addNotificationListener}.</p>
47 *
48 * <p>If the same listener is added more than once, it is considered as many times as it was
49 * added. It is often useful to add the same listener with different filters or handback
50 * objects.</p>
51 *
52 * <p>Implementations of this interface can differ regarding the thread in which the methods
53 * of filters and listeners are called.</p>
54 *
55 * <p>If the method call of a filter or listener throws an {@link Exception}, then that
56 * exception should not prevent other listeners from being invoked. However, if the method
57 * call throws an {@link Error}, then it is recommended that processing of the notification
58 * stop at that point, and if it is possible to propagate the {@code Error} to the sender of
59 * the notification, this should be done.</p>
60 *
61 * <p>New code should use the {@link NotificationEmitter} interface
62 * instead.</p>
63 *
64 * <p>Implementations of this interface and of {@code NotificationEmitter}
65 * should be careful about synchronization. In particular, it is not a good
66 * idea for an implementation to hold any locks while it is calling a
67 * listener. To deal with the possibility that the list of listeners might
68 * change while a notification is being dispatched, a good strategy is to
69 * use a {@link CopyOnWriteArrayList} for this list.
70 *
71 * @since 1.5
72 */
73 public interface NotificationBroadcaster {
74
75 /**
76 * Adds a listener to this MBean.
77 *
78 * @param listener The listener object which will handle the
79 * notifications emitted by the broadcaster.
80 * @param filter The filter object. If filter is null, no
81 * filtering will be performed before handling notifications.
82 * @param handback An opaque object to be sent back to the
83 * listener when a notification is emitted. This object cannot be
84 * used by the Notification broadcaster object. It should be
85 * resent unchanged with the notification to the listener.
86 *
87 * @exception IllegalArgumentException Listener parameter is null.
88 *
89 * @see #removeNotificationListener
90 */
91 public void addNotificationListener(NotificationListener listener,
92 NotificationFilter filter,
93 Object handback)
94 throws java.lang.IllegalArgumentException;
95
96 /**
97 * Removes a listener from this MBean. If the listener
98 * has been registered with different handback objects or
99 * notification filters, all entries corresponding to the listener
100 * will be removed.
101 *
102 * @param listener A listener that was previously added to this
103 * MBean.
104 *
105 * @exception ListenerNotFoundException The listener is not
106 * registered with the MBean.
107 *
108 * @see #addNotificationListener
109 * @see NotificationEmitter#removeNotificationListener
110 */
111 public void removeNotificationListener(NotificationListener listener)
112 throws ListenerNotFoundException;
113
114 /**
115 * <p>Returns an array indicating, for each notification this
116 * MBean may send, the name of the Java class of the notification
117 * and the notification type.</p>
118 *
119 * <p>It is not illegal for the MBean to send notifications not
120 * described in this array. However, some clients of the MBean
121 * server may depend on the array being complete for their correct
122 * functioning.</p>
123 *
124 * @return the array of possible notifications.
125 */
126 public MBeanNotificationInfo[] getNotificationInfo();
127 }
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