Glassfish example source code file (NotificationConnection.java)

This example Glassfish source code file (NotificationConnection.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Glassfish tags/keywords

closedchannelexception, connectioexception, interruptedexception, interruptedexception, ioexception, ioexception, log, logging, management, net, network, notificationconnection, notificationwrapper, notificationwrapper, objectoutputstream, rmi, simplequeue, socketexception, thread, thread

The Glassfish NotificationConnection.java source code

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 *
 * Copyright (c) 2006-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
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 * recipient has the option to distribute your version of this file under
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 * and therefore, elected the GPL Version 2 license, then the option applies
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package com.sun.enterprise.admin.jmx.remote.server.notification;

import java.io.*;
import java.nio.channels.ClosedChannelException;
import java.net.SocketException;
import java.rmi.ConnectException;
import java.rmi.ConnectIOException;
import java.util.logging.Logger;

import javax.management.*;

import com.sun.enterprise.admin.jmx.remote.DefaultConfiguration;
import com.sun.enterprise.admin.jmx.remote.notification.SimpleQueue;
import com.sun.enterprise.admin.jmx.remote.notification.NotificationWrapper;

/**
 * A Connection class that represents a single client connection.
 * This class maintains a notification buffer that is used to buffer notifications
 * that needs to be sent to the client that is being represented by an object of this class.
 * A dispatch thread is started, to dispatch the buffered notifications to the client.
 */
public class NotificationConnection implements Runnable {
    private SimpleQueue que = new SimpleQueue();
    private int bufsiz = 0;
    private Thread dispatchThr = null;
    private long lastNotifTime = 0;

    private OutputStream out = null;

    private boolean exiting = false;
    private boolean dispatching = false;
    private boolean isIOException = false;

    private static final Logger logger = Logger.getLogger(
        DefaultConfiguration.JMXCONNECTOR_LOGGER);/*, 
        DefaultConfiguration.LOGGER_RESOURCE_BUNDLE_NAME );*/

    public NotificationConnection(OutputStream out, int bufsiz) {
        this.out = out;
        if (bufsiz <= DefaultConfiguration.NOTIF_MIN_BUFSIZ)
            this.bufsiz = DefaultConfiguration.NOTIF_MAX_BUFSIZ;
        else
            this.bufsiz = bufsiz;
        dispatchThr = new Thread(this);
        dispatchThr.start();
    }

    /**
     * Reinitialized this connection and restarts the dispatch thread.
     * This method is called everytime the client reconnects to the server
     * because the connection had dropped.
     */
    public void reinit(OutputStream out) {
        this.out = out;
        isIOException = false;
        dispatchThr = new Thread(this);
        dispatchThr.start();
    }

    /**
     * Returns true if an IOException had occurred while dispatching a notification
     * to the client.
     * If true, then the connection to the client may have dropped.
     * If true, the ServerNotificationManager suspends this connection, waiting for
     * the client to reconnect.
     */
    public boolean hasIOExceptionOccurred() {
        return isIOException;
    }

    private boolean isIdle() {
        boolean ret = ((System.currentTimeMillis() - lastNotifTime) >= DefaultConfiguration.NOTIF_WAIT_INTERVAL);
        return ret;
    }
    
    /**
     * Sends an empty notification to the client.
     * An empty notification is sent every 10 seconds.
     */
    public void fireWaitNotif() {
        if (!hasIOExceptionOccurred() && (que.size() < bufsiz) && !dispatching && isIdle()) {
            synchronized (que) {
                que.add(new NotificationWrapper(NotificationWrapper.WAIT, null, null));
                que.notify();
            }
        }
    }

    /**
     * Called by the ServerNotificationManager whenever a notification needs to be
     * sent to the client.
     */
    public void fireNotification(NotificationWrapper wrapr) {
        if (que.size() < bufsiz) {
            synchronized (que) {
                que.add(wrapr);
                que.notify();
            }
        }
    }

    /**
     * When the server-side connector webapp is shutdown by the servlet container,
     * the ServerNotificationManager calls this method.
     * All pending notifications are dropped.
     */
    public void close() {
        exiting = true;
        synchronized (que) {
            que.notify();
        }
        try {
            dispatchThr.join();
        } catch (InterruptedException intre) {
        }
        try {
            out.close();
        } catch (IOException ioe) {
            // XXX: Log it
        }
    }

    public boolean isExiting() {
        return exiting;
    }

    /**
     * The notifications dispatch thread.
     * The dispatch thread sends all pending notifications in the buffer to the client.
     * The dispatch thread exits, whenever an IOException occurs during actual dispatch
     * or whenever this connection is being closed (after a call to close())
     */
    public void run() {
        /* XXX: Even when we are exiting should we send the remaining notifications?
         *      OR just drop the remaining notifications ?
         *
         *     Currently we drop all the remaining notifications!!
         */
        while (!isExiting() && !hasIOExceptionOccurred()) {
            synchronized (que) {
                while (que.isEmpty() && !isExiting() && !hasIOExceptionOccurred()) {
                    try {
                        que.wait();
                    } catch (InterruptedException intre) {
                    }
                }
            }
            if (isExiting() || hasIOExceptionOccurred())
                break;
            dispatching = true;
            while (!que.isEmpty() && !isExiting() && !hasIOExceptionOccurred()) {
                NotificationWrapper wrapr = (NotificationWrapper) que.remove();
                try {
                    sendNotificationMsg(wrapr);
                } catch (IOException ioe) {
                    if (isExiting())
                        break;
                    // XXX: Log it; drop the notification
                    if (!isDisconnected(ioe))
                        break;
                    isIOException = true;
                    synchronized (this) {
                        this.notify();
                    }
                    break;
                }
            }
            lastNotifTime = System.currentTimeMillis();
            dispatching = false;
        }
    }

    private boolean isDisconnected(IOException ioe) {
        if (ioe instanceof ClosedChannelException ||
            ioe instanceof SocketException ||
            ioe instanceof ConnectException ||
            ioe instanceof ConnectIOException)
            return true;
        return false;
    }

    private void sendNotificationMsg(NotificationWrapper wrapr) throws IOException {
        ObjectOutputStream objout = new ObjectOutputStream(out);
        objout.writeObject(wrapr);
        objout.flush();
    }
}