/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cocoon.components.jms;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.naming.NamingException;
import org.apache.avalon.framework.CascadingException;
import org.apache.avalon.framework.activity.Disposable;
import org.apache.avalon.framework.activity.Initializable;
import org.apache.avalon.framework.logger.AbstractLogEnabled;
import org.apache.avalon.framework.parameters.ParameterException;
import org.apache.avalon.framework.parameters.Parameterizable;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.avalon.framework.service.Serviceable;
import org.apache.avalon.framework.thread.ThreadSafe;
import org.apache.cocoon.caching.EventAware;
import org.apache.cocoon.caching.validity.Event;
import org.apache.cocoon.caching.validity.NamedEvent;
/**
* JMS listener will notify an {@link org.apache.cocoon.caching.EventAware} component
* of external events. This could be used for example to do external cache invalidation.
* Configuration parameters default to <a href="http://openjms.sf.net">OpenJMS</a> demo
* installation on localhost using "topic1".
*
* <p>Parameters:</p>
* <table>
* <tbody>
* <tr><td>connection </td><td>(required, no default)</td></tr>
* <tr><td>component </td><td>(required, no default)</td></tr>
* <tr><td>message-selector</td><td>("")</td></tr>
* </tbody>
* </table>
*
* @version CVS $Id: JMSEventListener.java,v 1.10 2004/03/05 13:01:57 bdelacretaz Exp $
* @author <a href="mailto:chaul@apache.org">chaul</a>
*/
public class JMSEventListener
extends AbstractLogEnabled
implements Serviceable, Parameterizable, MessageListener, Initializable, Disposable, ThreadSafe {
protected String selector = "";
protected ServiceManager manager;
protected String serviceName = null;
protected EventAware service = null;
protected String connectionName = null;
protected JMSConnection connection = null;
/*
* @see org.apache.avalon.framework.service.Serviceable#service(org.apache.avalon.framework.service.ServiceManager)
*/
public void service(ServiceManager manager) throws ServiceException {
this.manager = manager;
}
/*
* @see org.apache.avalon.framework.parameters.Parameterizable#parameterize(org.apache.avalon.framework.parameters.Parameters)
*/
public void parameterize(Parameters parameters) throws ParameterException {
this.connectionName = parameters.getParameter("connection");
this.serviceName = parameters.getParameter("component");
this.selector = parameters.getParameter("message-selector", this.selector);
}
public void initialize() {
try {
this.connection = (JMSConnection) this.manager.lookup(JMSConnection.ROLE+"/"+this.connectionName);
this.connection.registerListener(this, this.selector);
} catch (ServiceException e) {
if (getLogger().isWarnEnabled()) {
getLogger().warn("Could not obtain JMSConnection", e);
}
} catch (JMSException e) {
if (getLogger().isWarnEnabled()) {
getLogger().warn("Could not obtain JMSConnection", e);
}
} catch (NamingException e) {
if (getLogger().isWarnEnabled()) {
getLogger().warn("Could not obtain JMSConnection", e);
}
} catch (CascadingException e) {
if (getLogger().isWarnEnabled()) {
getLogger().warn("Could not obtain JMSConnection", e);
}
}
}
/* (non-Javadoc)
* @see org.apache.avalon.framework.activity.Disposable#dispose()
*/
public void dispose() {
if (this.manager != null){
this.manager.release(connection);
this.manager.release(service);
}
}
/*
* @see javax.jms.MessageListener#onMessage(javax.jms.Message)
*/
public synchronized void onMessage(Message message) {
EventAware service = this.service;
try {
if (service == null) {
service = (EventAware) this.manager.lookup(this.serviceName);
}
Event[] events = eventsFromMessage(message);
for (int i = 0; i < events.length; i++) {
if (this.getLogger().isDebugEnabled())
this.getLogger().debug(
"Notifying "
+ this.serviceName
+ " of "
+ events[i]);
service.processEvent(events[i]);
}
} catch (ServiceException e) {
if (this.getLogger().isErrorEnabled()) {
this.getLogger().error(
"Could not obtain " + this.serviceName + " from component manager.",
e);
}
} finally {
if (service instanceof ThreadSafe) {
this.service = service;
} else {
this.manager.release(service);
}
}
}
/**
* Convert the message contents to (a series of) cache event. The default implementation
* assumes that the message contains the trigger name, a '|', and a table name.
* It extracts the tablename and creates a NamedEvent with it.
* Override this method to provide your own message to event mappings.
*
* @param message the JMS message.
* @return the cache event.
*/
protected Event[] eventsFromMessage(Message message) {
String name = message.toString();
int pos = name.indexOf('|');
return new Event[] { new NamedEvent(name.substring(pos + 1)) };
}
}