/*
* Copyright 2001-2002,2004 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.commons.modeler;
import java.util.Enumeration;
import java.util.Hashtable;
import javax.management.AttributeChangeNotification;
import javax.management.InstanceNotFoundException;
import javax.management.MBeanException;
import javax.management.MBeanServer;
import javax.management.MBeanServerNotification;
import javax.management.Notification;
import javax.management.NotificationBroadcaster;
import javax.management.NotificationListener;
import javax.management.ObjectName;
import javax.naming.Context;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
// EXPERIMENTAL. It may fit better in tomcat jndi impl.
/**
*
* Link between JNDI and JMX. JNDI can be used for persistence ( it is
* an API for storing hierarchical data and a perfect fit for that ), as
* well as an alternate view of the MBean registry.
*
* If this component is enabled, all MBeans will be registered in JNDI, and
* all attributes that are set via JMX can be stored in a DirContext.
*
* This acts as a "recorder" for creation of mbeans and attribute changes
* done via JMX.
*
* XXX How can we control ( filter ) which mbeans will be registere ? Or
* attributes ?
* XXX How can we get the beans and attributes loaded before jndijmx ?
*
* The intended use:
* - do whatever you want to start the application
* - load JndiJmx as an mbean
* - make changes via JMX. All changes are recorded
* - you can use JndiJmx to save the changes in a Jndi context.
* - you can use JndiJmx to load changes from a JndiContext and replay them.
*
* The main benefit is that only changed attributes are saved, and the Jndi
* layer can preserve most of the original structure of the config file. The
* alternative is to override the config files with config info extracted
* from the live objects - but it's very hard to save only what was actually
* changed and preserve structure and comments.
*
* @author Costin Manolache
*/
public class JndiJmx extends BaseModelMBean implements NotificationListener {
private static Log log= LogFactory.getLog(JndiJmx.class);
protected Context componentContext;
protected Context descriptorContext;
protected Context configContext;
MBeanServer mserver;
/**
* Protected constructor to require use of the factory create method.
*/
public JndiJmx() throws MBeanException {
super(JndiJmx.class.getName());
}
/** If a JNDI context is set, all components
* will be registered in the context.
*
* @param ctx
*/
public void setComponentContext(Context ctx) {
this.componentContext= ctx;
}
/** JNDI context for component descriptors ( metadata ).
*
* @param ctx
*/
public void setDescriptorContext(Context ctx) {
this.descriptorContext= ctx;
}
/** JNDI context where attributes will be stored for persistence
*
*/
public void setConfigContext( Context ctx ) {
this.configContext= ctx;
}
// -------------------- Registration/unregistration --------------------
// temp - will only set in the jndi contexts
Hashtable attributes=new Hashtable();
Hashtable instances=new Hashtable();
public void handleNotification(Notification notification, Object handback)
{
// register/unregister mbeans in jndi
if( notification instanceof MBeanServerNotification ) {
MBeanServerNotification msnot=(MBeanServerNotification)notification;
ObjectName oname=msnot.getMBeanName();
if( "jmx.mbean.created".equalsIgnoreCase( notification.getType() )) {
try {
Object mbean=mserver.getObjectInstance(oname);
if( log.isDebugEnabled() )
log.debug( "MBean created " + oname + " " + mbean);
// XXX add filter support
if( mbean instanceof NotificationBroadcaster ) {
// register for attribute changes
NotificationBroadcaster nb=(NotificationBroadcaster)mbean;
nb.addNotificationListener(this, null, null);
if( log.isDebugEnabled() )
log.debug( "Add attribute change listener");
}
instances.put( oname.toString(), mbean );
} catch( InstanceNotFoundException ex ) {
log.error( "Instance not found for the created object", ex );
}
}
if( "jmx.mbean.deleted".equalsIgnoreCase( notification.getType() )) {
instances.remove(oname.toString());
}
}
// set attributes in jndi
// if( "jmx.attribute.changed".equals( notification.getType() )) {
if( notification instanceof AttributeChangeNotification) {
AttributeChangeNotification anotif=(AttributeChangeNotification)notification;
String name=anotif.getAttributeName();
Object value=anotif.getNewValue();
Object source=anotif.getSource();
String mname=null;
Hashtable mbeanAtt=(Hashtable)attributes.get( source );
if( mbeanAtt==null ) {
mbeanAtt=new Hashtable();
attributes.put( source, mbeanAtt);
if( log.isDebugEnabled())
log.debug("First attribute for " + source );
}
mbeanAtt.put( name, anotif );
log.debug( "Attribute change notification " + name + " " + value + " " + source );
}
}
public String dumpStatus() throws Exception
{
StringBuffer sb=new StringBuffer();
Enumeration en=instances.keys();
while (en.hasMoreElements()) {
String on = (String) en.nextElement();
Object mbean=instances.get(on);
Hashtable mbeanAtt=(Hashtable)attributes.get(mbean);
sb.append( "<mbean class=\"").append(on).append("\">");
sb.append( "\n");
Enumeration attEn=mbeanAtt.keys();
while (attEn.hasMoreElements()) {
String an = (String) attEn.nextElement();
AttributeChangeNotification anotif=
(AttributeChangeNotification)mbeanAtt.get(an);
sb.append(" <attribute name=\"").append(an).append("\" ");
sb.append("value=\"").append(anotif.getNewValue()).append("\">");
sb.append( "\n");
}
sb.append( "</mbean>");
sb.append( "\n");
}
return sb.toString();
}
public void replay() throws Exception
{
}
public void init() throws Exception
{
MBeanServer mserver=(MBeanServer)Registry.getRegistry().getMBeanServer();
ObjectName delegate=new ObjectName("JMImplementation:type=MBeanServerDelegate");
// XXX need to extract info about previously loaded beans
// we'll know of all registered beans
mserver.addNotificationListener(delegate, this, null, null );
}
}