JMX, SNMP, Java, etc...

/*
 * CustomAgent.java
 *
 * 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.
 * 
 * Created on Jul 25, 2007, 11:42:49 AM
 * 
 */

package example.rmi.agent;

import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.net.InetAddress;
import java.rmi.registry.LocateRegistry;
import java.util.HashMap;
import javax.management.MBeanServer;
import javax.management.remote.JMXConnector;
import javax.management.remote.JMXConnectorServer;
import javax.management.remote.JMXConnectorServerFactory;
import javax.management.remote.JMXServiceURL;
import javax.management.remote.rmi.RMIConnector;
import javax.management.remote.rmi.RMIConnectorServer;
import javax.rmi.ssl.SslRMIClientSocketFactory;
import javax.rmi.ssl.SslRMIServerSocketFactory;

/**
 * This CustomAgent will start an RMI Connector Server using only
 * port "example.rmi.agent.port". 
 *
 * @author dfuchs
 */
public class CustomAgent {

    private CustomAgent() { }
    
    /**
     * The CleanThread daemon thread will wait until all non-daemon threads
     * are terminated, excluding those non-daemon threads that are kept alive
     * by the presence of a started JMX RMI Connector Server. When no other
     * non-daemon threads remain, it stops the JMX RMI Connector Server,
     * allowing the application to terminate gracefully.
     **/
    public static class CleanThread extends Thread {
        private final JMXConnectorServer cs;
        public CleanThread(JMXConnectorServer cs) {
            super("JMX Agent Cleaner");
            this.cs = cs;
            setDaemon(true);
        }
        
        public void run() {
            boolean loop = true;
            try {
                while (loop) {
                    final Thread[] all = new Thread[Thread.activeCount()+100];
                    final int count = Thread.enumerate(all);
                    loop = false;
                    for (int i=0;i<count;i++) {
                        final Thread t = all[i];
                        // daemon: skip it.
                        if (t.isDaemon()) continue;
                        // RMI Reaper: skip it.
                        if (t.getName().startsWith("RMI Reaper")) continue;
                        if (t.getName().startsWith("DestroyJavaVM")) continue;
                        // Non daemon, non RMI Reaper: join it, break the for 
                        // loop, continue in the while loop (loop=true)
                        loop = true;
                        try {
                            // Found a non-daemon thread. Wait for it.
                            System.out.println("Waiting on "+t.getName()+
                                    " [id="+t.getId()+"]");
                            t.join();
                        } catch (Exception ex) {
                            ex.printStackTrace();
                        }
                        break;
                    }
                }
                // We went through a whole for-loop without finding any thread
                // to join. We can close cs.
            } catch (Exception ex) {
                ex.printStackTrace();
            } finally {
                try {
                    // if we reach here it means the only non-daemon threads
                    // that remain are reaper threads - or that we got an 
                    // unexpected exception/error.
                    //
                    cs.stop();
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        }
    }
    
    public static void premain(String agentArgs) 
        throws IOException {

        // Ensure cryptographically strong random number generator used
        // to choose the object number - see java.rmi.server.ObjID
        //
        System.setProperty("java.rmi.server.randomIDs", "true");

        // Start an RMI registry on port specified by example.rmi.agent.port
        // (default 3000).
        //
        final int port= Integer.parseInt(
                System.getProperty("example.rmi.agent.port","3412"));
        System.out.println("Create RMI registry on port "+port);
        
        // We create a couple of SslRMIClientSocketFactory and 
        // SslRMIServerSocketFactory. We will use the same factories to export
        // the RMI Registry and the JMX RMI Connector Server objects. This 
        // will allow us to use the same port for all the exported objects.
        // If we didn't use the same factories everywhere, we would have to
        // use at least two ports, because two different RMI Socket Factories
        // cannot share the same port.
        //
        final SslRMIClientSocketFactory csf = new SslRMIClientSocketFactory();
        final SslRMIServerSocketFactory ssf = new SslRMIServerSocketFactory();
        
        // Create the RMI Registry using the SSL socket factories above.
        // In order to use a single port, we must use these factories 
        // everywhere, or nowhere. Since we want to use them in the JMX
        // RMI Connector server, we must also use them in the RMI Registry.
        // Otherwise, we wouldn't be able to use a single port.
        //
        LocateRegistry.createRegistry(port, csf, ssf);

        // Retrieve the PlatformMBeanServer.
        //
        System.out.println("Get the platform's MBean server");
        MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();

        // Environment map.
        //
        System.out.println("Initialize the environment map");
        HashMap<String,Object> env = new HashMap<String,Object>();
        
        // Now specify the SSL Socket Factories:
        //
        // For the client side (remote)
        //
        env.put(RMIConnectorServer.RMI_CLIENT_SOCKET_FACTORY_ATTRIBUTE,csf);
        
        // For the server side (local)
        //
        env.put(RMIConnectorServer.RMI_SERVER_SOCKET_FACTORY_ATTRIBUTE,ssf);
        
        // For binding the JMX RMI Connector Server with the registry 
        // created above:
        //
        env.put("com.sun.jndi.rmi.factory.socket", csf);

        // Create an RMI connector server.
        //
        // As specified in the JMXServiceURL the RMIServer stub will be
        // registered in the RMI registry running in the local host on
        // port 3000 with the name "jmxrmi". This is the same name the
        // out-of-the-box management agent uses to register the RMIServer
        // stub too.
        //
        // The port specified in "service:jmx:rmi://"+hostname+":"+port
        // is the second port, where RMI connection objects will be exported.
        // Here we use the same port as that we choose for the RMI registry. 
        // The port for the RMI registry is specified in the second part
        // of the URL, in "rmi://"+hostname+":"+port
        //
        System.out.println("Create an RMI connector server");
        final String hostname = InetAddress.getLocalHost().getHostName();
        JMXServiceURL url =
            new JMXServiceURL("service:jmx:rmi://"+hostname+
            ":"+port+"/jndi/rmi://"+hostname+":"+port+"/jmxrmi");
        
        
        System.out.println("creating server with URL: "+url);
        
        // Now create the server from the JMXServiceURL
        //
        final JMXConnectorServer cs =
            JMXConnectorServerFactory.newJMXConnectorServer(url, env, mbs);

        // Start the RMI connector server.
        //
        System.out.println("Start the RMI connector server on port "+port);
        cs.start();
        System.out.println("Server started at: "+cs.getAddress());

        // Start the CleanThread daemon...
        //
        final Thread clean = new CleanThread(cs);
        clean.start();
    }
}