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Java > Open Source Codes > org > jboss > ha > singleton > HASingletonMBean


1 /*
2  * JBoss, Home of Professional Open Source
3  * Copyright 2005, JBoss Inc., and individual contributors as indicated
4  * by the @authors tag. See the copyright.txt in the distribution for a
5  * full listing of individual contributors.
6  *
7  * This is free software; you can redistribute it and/or modify it
8  * under the terms of the GNU Lesser General Public License as
9  * published by the Free Software Foundation; either version 2.1 of
10  * the License, or (at your option) any later version.
11  *
12  * This software is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with this software; if not, write to the Free
19  * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20  * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21  */
22 package org.jboss.ha.singleton;
23
24 import org.jboss.ha.jmx.HAServiceMBean;
25
26 /**
27  * HA-Singleton interface.
28  * Only one mbean is active at any point in time, cluster-wide.
29  * <p>
30  * The service provides a simple way for a concrete mbean to detect whether
31  * or not it is the active one in the cluster.
32  * <p>
33  * Concrete mbeans would usually do activities like regular clean up of database tables
34  * or saving statistics about cluster usage.
35  *
36  * @author <a HREF="mailto:ivelin@apache.org">Ivelin Ivanov</a>
37  * @author <a HREF="mailto:dimitris@jboss.org">Dimitris Andreadis</a>
38  * @version $Revision: 39540 $
39  */
40 public interface HASingletonMBean extends HAServiceMBean
41 {
42    // Constants -----------------------------------------------------
43
44    /** Notifications emitted locally by an HASingleton to indicate state transitions */
45    String JavaDoc HASINGLETON_STARTING_NOTIFICATION = "org.jboss.ha.singleton.starting";
46    String JavaDoc HASINGLETON_STARTED_NOTIFICATION = "org.jboss.ha.singleton.started";
47    String JavaDoc HASINGLETON_STOPPING_NOTIFICATION = "org.jboss.ha.singleton.stopping";
48    String JavaDoc HASINGLETON_STOPPED_NOTIFICATION = "org.jboss.ha.singleton.stopped";
49    
50    // Attributes ----------------------------------------------------
51
52     /** True if this cluster node has the active mbean singleton, false otherwise */
53     boolean isMasterNode();
54
55 }
56
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