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1 /*** 2 * Redistribution and use of this software and associated documentation 3 * ("Software"), with or without modification, are permitted provided 4 * that the following conditions are met: 5 * 6 * 1. Redistributions of source code must retain copyright 7 * statements and notices. Redistributions must also contain a 8 * copy of this document. 9 * 10 * 2. Redistributions in binary form must reproduce the 11 * above copyright notice, this list of conditions and the 12 * following disclaimer in the documentation and/or other 13 * materials provided with the distribution. 14 * 15 * 3. The name "Exolab" must not be used to endorse or promote 16 * products derived from this Software without prior written 17 * permission of Exoffice Technologies. For written permission, 18 * please contact info@exolab.org. 19 * 20 * 4. Products derived from this Software may not be called "Exolab" 21 * nor may "Exolab" appear in their names without prior written 22 * permission of Exoffice Technologies. Exolab is a registered 23 * trademark of Exoffice Technologies. 24 * 25 * 5. Due credit should be given to the Exolab Project 26 * (http://www.exolab.org/). 27 * 28 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS 29 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT 30 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 31 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 32 * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 33 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 34 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 35 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 37 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 38 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 39 * OF THE POSSIBILITY OF SUCH DAMAGE. 40 * 41 * Copyright 2001-2003 (C) Exoffice Technologies Inc. All Rights Reserved. 42 * 43 * $Id: QueueBrowserEndpoint.java,v 1.24 2003/08/13 13:30:54 tanderson Exp $ 44 * 45 * Date Author Changes 46 * 3/1/2001 jima Created 47 */ 48 package org.exolab.jms.messagemgr; 49 50 import java.util.Vector; 51 52 import javax.jms.InvalidSelectorException; 53 import javax.jms.Session; 54 55 import org.apache.commons.logging.Log; 56 import org.apache.commons.logging.LogFactory; 57 58 import org.exolab.jms.client.JmsDestination; 59 import org.exolab.jms.client.JmsQueue; 60 import org.exolab.jms.message.MessageHandle; 61 import org.exolab.jms.message.MessageImpl; 62 import org.exolab.jms.scheduler.Scheduler; 63 import org.exolab.jms.server.JmsServerSession; 64 65 66 /*** 67 * A QueueBrowserEndpoint is a QueueListener to a QueueDestinationCache. This 68 * enables it to receive all the messages, which it then feeds down to the 69 * client side. 70 * 71 * @version $Revision: 1.24 $ $Date: 2003/08/13 13:30:54 $ 72 * @author <a href="mailto:jima@exoffice.com">Jim Alateras</a> 73 */ 74 public class QueueBrowserEndpoint 75 extends ConsumerEndpoint 76 implements QueueListener { 77 78 /*** 79 * The destination that this consumer subscribes too 80 */ 81 private QueueDestinationCache _cache = null; 82 83 /*** 84 * The queue that this endpoint is subscribed too 85 */ 86 private JmsQueue _queue = null; 87 88 /*** 89 * The logger 90 */ 91 private static final Log _log = 92 LogFactory.getLog(QueueBrowserEndpoint.class); 93 94 95 /*** 96 * Construct a QueueConsumerEndpoint, that extends ConsumerEndpoint and 97 * is used to manage both synchronous and asynchronous message delivery 98 * for this consumer. 99 * 100 * @param session - the owning session 101 * @param clientId - uniquely identifies the remote client within session 102 * @param destination - destination that this object was created for 103 * @param selector - the selector attached to the consumer, if any. 104 * @param scheduler - used to schedule async message delivery. 105 * @throws InvalidSelectorException 106 */ 107 QueueBrowserEndpoint(JmsServerSession session, long clientId, 108 JmsQueue destination, String selector, 109 Scheduler scheduler) 110 throws InvalidSelectorException { 111 super(session, clientId, selector, scheduler); 112 113 _cache = (QueueDestinationCache) 114 DestinationManager.instance().getDestinationCache(destination); 115 // if a cache is not active then we need to create one. 116 if (_cache == null) { 117 _cache = (QueueDestinationCache) 118 DestinationManager.instance().createDestinationCache( 119 destination); 120 } 121 122 // cache the destination 123 _queue = destination; 124 125 // set up the message cache and register itself as a listener to the 126 // cache 127 _cache.addQueueListener(this); 128 _cache.playbackMessages(this); 129 130 } 131 132 /*** 133 * Deliver messages in the cache to the consumer.<p> 134 * This is not relevant to QueueBrowsers, and thus shouldn't be invoked. 135 * 136 * @return <code>false</code> 137 */ 138 public boolean deliverMessages() { 139 _log.error( 140 "QueueBrowserEndpoint.deliverMessages() should never be called", 141 new Exception()); 142 return false; 143 } 144 145 // implementation of ConsumerEndpoint.receiveMessage 146 public synchronized MessageHandle receiveMessage(long wait) { 147 throw new UnsupportedOperationException( 148 "Cannot call receiveMessage for QueueBrowser"); 149 } 150 151 /*** 152 * Return, at most, count messages from the cache. 153 * 154 * @param count - the max number of messages to receive 155 * @return Vector - number of messages 156 */ 157 public synchronized Vector receiveMessages(int count) { 158 Vector messages = new Vector(); 159 int index = 0; 160 while (index < count) { 161 162 // check if we should exit the loop 163 if (isStopped() || getMessageCount() == 0) { 164 break; 165 } 166 167 // remove the first message from the list and check 168 // that it is not null. Synchronize the removal of 169 // the message but not the sending to the remote 170 // consumer 171 try { 172 MessageHandle handle = removeFirstMessage(); 173 174 MessageImpl m = handle.getMessage(); 175 if (m != null) { 176 // add it to the list of messages to send 177 // but only deliver messsages that satisfy the 178 // selection criteria. 179 if ((_selector == null) || 180 (_selector.selects(m))) { 181 handle.setClientId(getClientId()); 182 messages.addElement(handle); 183 ++index; 184 } else { 185 // drop the message 186 } 187 } else { 188 // message may have been consumed in the interim 189 } 190 } catch (Exception exception) { 191 _log.error(exception, exception); 192 } 193 } 194 195 return messages; 196 } 197 198 199 // implementation of ConsumerEndpoint.getDestination 200 public JmsDestination getDestination() { 201 return _queue; 202 } 203 204 // implementation of ConsumerEndpoint.unregister 205 public void unregister() { 206 _cache.unregisterConsumer(this); 207 } 208 209 // override implementation of ConsumerEndpoint.returnMessage 210 public void returnMessage(MessageHandle handle) { 211 // no-op at the moment. What happens to a QueueBrowser when 212 // a transaction aborts. 213 } 214 215 // implementation of QueueListener.onMessage 216 public void onMessage(MessageImpl message) { 217 // delegate to message added, regardless of whether or not 218 // the message is persistent. 219 messageAdded(message); 220 } 221 222 // override ConsumerEndpoint.setMessageListener 223 public void setMessageListener(InternalMessageListener listener) { 224 _log.error( 225 "QueueBrowserEndpoint.setMessageListener should never be called"); 226 Thread.currentThread().dumpStack(); 227 } 228 229 /*** 230 * Closes this endpoint 231 */ 232 protected void doClose() { 233 // unregister from the DestinationCache 234 _cache.removeQueueListener(this); 235 } 236 237 }

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