/*
* JBoss, Home of Professional Open Source.
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.system;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.management.ObjectName;
import org.jboss.logging.Logger;
import org.jboss.mx.interceptor.AbstractInterceptor;
import org.jboss.mx.interceptor.DynamicInterceptor;
import org.jboss.mx.interceptor.Interceptor;
import org.jboss.mx.server.Invocation;
/**
* Helper class that can be used for writing MBean Services
* that dynamically hook-up an Interceptor to other (X)MBeans
* that have been configured as Interceptable.
*
* In a nutshell, call attach()/detach() from your
* createService()/destroyService() or startService()/stopService()
* pair methods to attach/detach an interceptor to the target mbean(s),
* then override invoke() to do something with the invocations.
*
* You may also provide your own Interceptor, in which case
* you should call attach(Interceptor).
*
* @author <a href="mailto:dimitris@jboss.org">Dimitris Andreadis</a>
* @version $Revision: 81033 $
*/
public abstract class InterceptorServiceMBeanSupport extends ServiceMBeanSupport
implements InterceptorServiceMBean
{
// Private Data --------------------------------------------------
/** The Interceptables to attach to */
private List interceptables;
/** The attached interceptor */
private Interceptor interceptor;
// Constructors -------------------------------------------------
/**
* Constructs an <tt>InterceptorServiceMBeanSupport</tt>.
*/
public InterceptorServiceMBeanSupport()
{
super();
}
/**
* Constructs an <tt>InterceptorServiceMBeanSupport</tt>.
*
* Pass-through to ServiceMBeanSupport.
*
* @param type The class type to determine Logger name from.
*/
public InterceptorServiceMBeanSupport(final Class type)
{
super(type);
}
/**
* Constructs an <tt>InterceptorServiceMBeanSupport</tt>.
*
* Pass-through to ServiceMBeanSupport.
*
* @param category The logger category name.
*/
public InterceptorServiceMBeanSupport(final String category)
{
super(category);
}
/**
* Constructs an <tt>InterceptorServiceMBeanSupport</tt>.
*
* Pass-through to ServiceMBeanSupport.
*
* @param log The logger to use.
*/
public InterceptorServiceMBeanSupport(final Logger log)
{
super(log);
}
// InterceptorServiceMBean ---------------------------------------
public void setInterceptables(List interceptables)
{
// copy
if (interceptables != null)
{
this.interceptables = new ArrayList(interceptables);
}
}
public List getInterceptables()
{
// return a copy
if (interceptables != null)
{
return new ArrayList(interceptables);
}
return null;
}
// Protected API -------------------------------------------------
/**
* Add our interceptor to the target Interceptables.
*
* Override invoke(Invocation) to handle the calls.
*
* @throws Exception thrown on any interceptor registration error
*/
protected void attach() throws Exception
{
if (interceptor == null)
{
attach(new XMBeanInterceptor());
}
}
/**
* Add the provided interceptor to the target Interceptables.
*
* @param interceptor the interceptor to add
* @throws Exception thrown on any interceptor registration error
*/
protected void attach(Interceptor interceptor) throws Exception
{
if (interceptor == null)
{
throw new IllegalArgumentException("Null interceptor");
}
// check we haven't attached already
if (this.interceptor != null)
{
throw new IllegalStateException("Interceptor already attached");
}
log.debug("Attaching interceptor: " + interceptor.getName());
// remember the interceptor
this.interceptor = interceptor;
// add the interceptor to the Interceptables; an exception
// will be thrown if any of them is not Interceptable,
// in which case detach() should be called.
if (interceptables != null)
{
Object[] params = new Object[] { interceptor };
String[] signature = new String[] { Interceptor.class.getName() };
for (Iterator i = interceptables.iterator(); i.hasNext(); )
{
ObjectName target = (ObjectName)i.next();
super.server.invoke(target,
DynamicInterceptor.ADD_INTERCEPTOR,
params,
signature);
log.debug("Interceptor attached to: '" + target + "'");
}
}
}
/**
* Remove the interceptor from the target Interceptables
*/
protected void detach()
{
if (interceptor != null)
{
log.debug("Detaching interceptor: " + interceptor.getName());
if (interceptables != null)
{
Object[] params = new Object[] { interceptor };
String[] signature = new String[] { Interceptor.class.getName() };
for (Iterator i = interceptables.iterator(); i.hasNext(); )
{
ObjectName target = (ObjectName)i.next();
try
{
super.server.invoke(target,
DynamicInterceptor.REMOVE_INTERCEPTOR,
params,
signature);
log.debug("Interceptor detached from: '" + target + "'");
}
catch (Exception e)
{
log.debug("Caught exception while removing interceptor from '" +
target + "'", e);
}
}
}
interceptor = null;
}
}
/**
* Use this to forward the call
*/
protected Object invokeNext(Invocation invocation) throws Throwable
{
// call the next in the interceptor chain,
// if nobody follows dispatch the call
Interceptor next = invocation.nextInterceptor();
if (next != null)
{
return next.invoke(invocation);
}
else
{
return invocation.dispatch();
}
}
// Override ------------------------------------------------------
/**
* Override
*/
protected Object invoke(Invocation invocation) throws Throwable
{
return invokeNext(invocation);
}
// Private Inner Class -------------------------------------------
/**
* Simple Interceptor delegating to
* the invoke(Invocation) callback
*/
private class XMBeanInterceptor extends AbstractInterceptor
{
public XMBeanInterceptor()
{
super("XMBeanInterceptor('" + InterceptorServiceMBeanSupport.this.getServiceName() + "')");
}
public Object invoke(Invocation invocation) throws Throwable
{
// delegate
return InterceptorServiceMBeanSupport.this.invoke(invocation);
}
}
}