JMX, SNMP, Java, etc...

A Main class that creates applications whose MBeans are registered in an application-private MBeanServer, and then federates all these MBeanServers in a global MBeanServer - this example uses the platform MBeanServer: if you wanted to keep all applications really isolated and prevent them to access each other's MBeans by any means, and didn't want to set up a complex java policy file, you would probably create and use another MBeanServer for that, since the application code could also call ManagementFactory.getPlatformMBeanServer().

An ApplicationContoller MBean that we use for the sake of the example: since I had to code and set up two dummy applications that basically did the same thing (create an application MBeanServer and register their MBeans in it) I choose to factorize all this common code in a base ApplicationController MBean - of which each application provide its own subclass. You can view these ApplicationContollers as the main JMX entry point (MBean setup) for each application. Of course in the real world you do not need your applications to share any code: all you need is a reference to a private MBeanServer in which the application has registered its own MBeans.

Dummy application MBeans for each applications. Application A has Wombat MBeans, and Application B has Bandicoot MBeans.

The Main class creates an instance of Application A and mounts its MBeanServer in a directory "a" in the platform MBeanServer. Then it creates two instances of Application B, and mounts them in directories "b1" and "b2" respectively.

The tree on the left shows how the platform MBeanServer now looks like. If we were using JMX 2.0, we would not be seeing the mounted MBeans at this level. We would see only special MBeans called NamespaceHandlers, on which we would have to click in order to enter their namespaces (in this case, the corresponding private application MBeanServer).

The popup on the right part of the image shows all the MBeans that the BandicootMBean bandicoot0 was able to find using queryNames(null,null) on its MBeanServer reference. This is because each application is using a private MBeanServer, and the global MBeanServer in which they all have been federated was not provided to them.

    
/*
 * Main.java
 *
 * Created on May 9, 2007, 5:51 PM
 *
 * SCCS: %W%
 *
 * Copyright 2007 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.
 */

package example.opendmk.cascading;

import com.sun.jdmk.remote.cascading.CascadingAgent;
import com.sun.jdmk.remote.cascading.LocalMBeanServerConnectionFactory;
import com.sun.jdmk.remote.cascading.MBeanServerConnectionFactory;
import com.sun.jdmk.remote.cascading.proxy.ProxyCascadingAgent;
import example.application.ApplicationController;
import example.application.a.ApplicationA;
import example.application.b.ApplicationB;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.util.logging.Logger;
import javax.management.JMException;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;

/**
 * In this example we're going to:
 * <ul><li>
 *     Create an instance of Application A and two instances of Application B,
 * </li><li>
 *     Register each application instance in its own MBeanServer,
 * </li><li>
 *     Mount each application's MBeanServer in a global MBeanServer.
 * </li></ul>
 * <p>
 * For the sake of simplicity, we're going to use the platform MBeanServer
 * as global MBeanServer. This will make it possible to use the default
 * JVM agent to expose the applications MBeans.
 * <p>
 * @author Sun Microsystems, 2007 - All rights reserved.
 */
public class Main {
    
    /**
     * Main logger for this class.
     */
    private static final Logger LOG =
            Logger.getLogger(Main.class.getName());
        
    /**
     * Creates an OpenDMK cascading agent to mount a controlled application
     * MBeanServer inside a global target MBeanServer.
     * @param target the global MBeanServer which is the target of the mount.
     * @param name the directory name in which we will mount the controlled
     *             application MBeanServer.
     * @param appl the ApplicationController for the controlled application 
     *        whose MBeanServer we want to mount.
     **/
    private static CascadingAgent createCascadingAgentFor(MBeanServer target,
            String name, ApplicationController appl) {
        final MBeanServerConnectionFactory mbsfa = 
                new LocalMBeanServerConnectionFactory(appl.getMBeanServer(),
                "application "+name);
        return new ProxyCascadingAgent(mbsfa,null,null,name,
                target,"application "+name);
    }
    
    /**
     * Mounts a controlled application MBeanServer inside a global target 
     * MBeanServer.
     * @param target the global MBeanServer which is the target of the mount.
     * @param name the directory name in which we will mount the controlled
     *             application MBeanServer.
     * @param appl the ApplicationController for the controlled application 
     *        whose MBeanServer we want to mount.
     * @return The OpenDMK CascadingAgent which controls the mount point.
     **/
    public static CascadingAgent mount(MBeanServer target, String name, 
            ApplicationController appl) 
        throws JMException, IOException {
        appl.register();
        final CascadingAgent ag = createCascadingAgentFor(target,name,appl);
        target.registerMBean(ag,getCascadingAgentNameFor(name));
        ag.start();
        return ag;
    }
    
    /**
     * A name for the OpenDMK CascadingAgent that will control the mount point
     * for the given directory.
     * @name the directory name controlled by this cascading agent.
     **/
    public static ObjectName getCascadingAgentNameFor(String name) 
        throws MalformedObjectNameException {
       return new ObjectName("opendmk.cascading.agents:type=CascadingAgent,name="+name);
    }
    
    /**
     * In this example we're going to:
     * <ul><li>
     *     Create an instance of Application A and two instances of Application B,
     * </li><li>
     *     Register each application instance in its own MBeanServer,
     * </li><li>
     *     Mount each application's MBeanServer in a global MBeanServer.
     * </li></ul>
     * <p>
     * For the sake of simplicity, we're going to use the platform MBeanServer
     * as global MBeanServer. This will make it possible to use the default
     * JVM agent to expose the applications MBeans.
     * <p>
     * We will then be able to see *all* MBeans with JConsole, but you will
     * notice that applications MBean can only see the MBeans registered
     * in their own application instance MBeanServer (use JConsole to call
     * WombatMBean.explore() or BandicootMBean.explore().
     * @param args none.
     */
    public static void main(String[] args) throws Exception {
        final MBeanServer server = ManagementFactory.getPlatformMBeanServer();
        final ApplicationA a  = new ApplicationA("a");
        final ApplicationB b1 = new ApplicationB("b1");
        final ApplicationB b2 = new ApplicationB("b2");
        final CascadingAgent ca  = mount(server,"a",a);
        final CascadingAgent cb1 = mount(server,"b1",b1);
        final CascadingAgent cb2 = mount(server,"b2",b2);
        System.out.println("Now use JCondsole to connect to " +
                ManagementFactory.getRuntimeMXBean().getName());
        System.out.println("Strike <Enter> to exit: ");
        System.in.read();
    }
    
}