001 /*
002 * Copyright (C) The Apache Software Foundation. All rights reserved.
003 *
004 * This software is published under the terms of the Apache Software License
005 * version 1.1, a copy of which has been included with this distribution in
006 * the LICENSE file.
007 *
008 * $Id: MessengerManager.java 155459 2005-02-26 13:24:44Z dirkv $
009 */
010 package org.apache.commons.messenger;
011
012 import java.net.URL;
013 import java.util.Hashtable;
014 import java.util.Iterator;
015 import java.util.Map;
016
017 import javax.jms.JMSException;
018
019 import org.apache.commons.logging.Log;
020 import org.apache.commons.logging.LogFactory;
021
022 /** <p><code>MessengerManager</code> is a manager of {@link Messenger} instances.</p>
023 *
024 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
025 * @version $Revision: 155459 $
026 */
027 public class MessengerManager {
028
029 /** Logger */
030 private static final Log log = LogFactory.getLog( MessengerManager.class );
031
032 /** The singleton MessengerManager used by the static get() method */
033 private static MessengerManager singleton;
034
035 /** A map where the key = name and value = messenger */
036 private Map messengers = new Hashtable();
037
038
039 public MessengerManager() {
040 }
041
042
043 /** Uses the default configuration mechanism this method will return
044 * the Messenger for the given name. The Messenger.xml file will be searched
045 * on the classpath
046 */
047 public static Messenger get( String name ) throws JMSException {
048 return getInstance().getMessenger( name );
049 }
050
051 /** A helper method to load a MessengerManager
052 * from a given XML deployment configuration document
053 */
054 public static MessengerManager load( String xmlURL ) throws JMSException {
055 try {
056 MessengerDigester digester = new MessengerDigester();
057 return (MessengerManager) digester.parse( xmlURL );
058 }
059 catch (Exception e) {
060 JMSException newException = new JMSException(
061 "Could not load the Messenger XML config file from: " + xmlURL
062 + ". Underlying reason: " + e
063 );
064 newException.setLinkedException(e);
065 throw newException;
066 }
067 }
068
069 /** A helper method to explicitly configure the MessengerManager singleton
070 * from a given XML deployment configuration document
071 */
072 public static void configure( String xmlURL ) throws JMSException {
073 setInstance( load( xmlURL ) );
074 }
075
076 /** Returns the messenger for the given name */
077 public Messenger getMessenger(String name) {
078 return (Messenger) messengers.get(name);
079 }
080
081 public void addMessenger(Messenger messenger) {
082 messengers.put(messenger.getName(), messenger);
083 }
084
085 public void removeMessenger(Messenger messenger) {
086 messengers.remove(messenger.getName());
087 }
088
089 /** Returns an iterator over the names of the available Messenger instances */
090 public Iterator getMessengerNames() {
091 return messengers.keySet().iterator();
092 }
093
094 /** Returns the singleton MessengerManager */
095 public synchronized static MessengerManager getInstance() throws JMSException {
096 if ( singleton == null ) {
097 singleton = createInstance();
098 }
099 return singleton;
100 }
101
102 /** Installs a new singleton MessengerManager instance */
103 public static void setInstance(MessengerManager messengerManager) {
104 singleton = messengerManager;
105 }
106
107 public void close() {
108 synchronized (messengers) {
109 for ( Iterator iter = messengers.entrySet().iterator(); iter.hasNext(); ) {
110 Map.Entry entry = (Map.Entry) iter.next();
111 String name = entry.getKey().toString();
112 Messenger messenger = (Messenger) entry.getValue();
113 iter.remove();
114 try {
115 messenger.close();
116 }
117 catch (Exception e) {
118 log.error(
119 "Caught exception trying to close messenger: " + name
120 + " Exception: " + e,
121 e
122 );
123 // continue to close all connections even if an error occurs
124 }
125 }
126 }
127 }
128
129 // Implementation methods
130 //-------------------------------------------------------------------------
131
132 /** Factory method to create the singleton MessengerManager instance */
133 protected static MessengerManager createInstance() throws JMSException {
134 String config = null;
135 try {
136 config = System.getProperty( "org.apache.commons.messenger" );
137 }
138 catch (Exception e) {
139 }
140 if ( config != null ) {
141 return load( config );
142 }
143 URL url = MessengerManager.class.getClassLoader().getResource( "Messenger.xml" );
144 if ( url == null ) {
145 // lets try the threads class loader
146 ClassLoader loader = Thread.currentThread().getContextClassLoader();
147 url = loader.getResource( "Messenger.xml" );
148 }
149 if ( url != null ) {
150 return load( url.toString() );
151 }
152 else {
153 throw new JMSException( "No Messenger.xml configuration document found on the CLASSPATH. Could not initialise the default MessengerManager!!" );
154 }
155 }
156
157 }
158