JMX, SNMP, Java, etc...

/*
 * DontDoThis.java
 *
 * Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * Created on Jul 25, 2007, 11:42:49 AM
 * 
 */

package dontdothis;

import java.io.IOException;
import java.io.Serializable;
import java.lang.management.ManagementFactory;
import javax.management.JMException;
import javax.management.JMX;
import javax.management.MBeanServer;
import javax.management.MBeanServerConnection;
import javax.management.ObjectInstance;
import javax.management.ObjectName;
import javax.management.StandardMBean;
import javax.management.remote.JMXConnector;
import javax.management.remote.JMXConnectorFactory;
import javax.management.remote.JMXConnectorServer;
import javax.management.remote.JMXConnectorServerFactory;
import javax.management.remote.JMXServiceURL;

/**
 * This trick only works with standard MBean and MXBeans.
 * @author dfuchs
 */
public class DontDoThis {

    // A dummy interface for my dummy MBean
    public static interface ThingMBean {
        // Get A foo for my thing
        public String getFoo();
        // Set A foo for my thing
        public void setFoo(String value);
    }

    // A dummy implementation for my dummy MBean
    public static class Thing implements ThingMBean, Serializable {
         // Attribute : Foo
        private String foo;

        public Thing(String foo) {this.foo = foo;}
        // Get A foo gor my thing
        public String getFoo() {return foo;}
        // Set A foo gor my thing
         public void setFoo(String value) {foo = value;}
    }

    // Create a server... we're simulating a remote server
    // here by starting an RMI JMXConnectorServer...
    public static JMXServiceURL createServer() 
            throws IOException {         
        final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
        final JMXServiceURL jurl = new JMXServiceURL("rmi", null, 0);
        final JMXConnectorServer server =
                JMXConnectorServerFactory.newJMXConnectorServer(jurl, null, mbs);
        server.start();
        return server.getAddress();
    }
    
    // Here is the trick: instead of registering x directly, we wrap it
    // in an instance of javax.management.StandardMBean, and we use
    // createMBean to create the wrapper.
    //
    public static ObjectInstance registerMBean(MBeanServerConnection mbsc,
            ObjectName mbeanName, Object mbean, Class<?> mbeanInterface) 
            throws IOException, JMException {
        
        // create a Standard MBean,
        return mbsc.createMBean(StandardMBean.class.getName(), mbeanName,
                new Object[]{mbean, mbeanInterface}, 
                new String[]{Object.class.getName(),Class.class.getName()});
    }
    
    // Well: you've been warned: don't do this!
    public static void main(String[] args) throws Exception {
        
        final JMXServiceURL serverURL = createServer();

        // Instantiate the MBean we want to register
        final ThingMBean x = new Thing("I am a nice Thing!");
        final ObjectName xName = new ObjectName("x:x=x");
        
        // we're simulating a remote client by connecting to the server
        // through RMI
        final JMXConnector c = JMXConnectorFactory.connect(serverURL);
        final MBeanServerConnection mbsc = c.getMBeanServerConnection();
        
        // register MBean x in remote server.
        registerMBean(mbsc,xName,x,ThingMBean.class);

        // create a proxy to the registered MBean
        final ThingMBean x2 = JMX.newMBeanProxy(mbsc, xName, ThingMBean.class);

        // modify the original reference:
        x.setFoo("... but I have turned bad.");

        // x & the registered MBean are now 2 different objects!
        System.out.println(xName.toString() + " says: " + x2.getFoo());
        System.out.println("x says: " + x.getFoo());

        System.out.println("Now waiting for Enter: ");
        System.in.read();

    }
}