/*
 *
 * Copyright 2002 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.
 * 
 * - Redistribution 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, Inc. or the names of
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY
 * DAMAGES OR LIABILITIES SUFFERED BY LICENSEE AS A RESULT OF OR
 * RELATING TO USE, MODIFICATION OR DISTRIBUTION OF THIS SOFTWARE OR
 * ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE
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 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF
 * THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS
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 * 
 * You acknowledge that this software is not designed, licensed or
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 */
import javax.naming.*;
import javax.jms.*;

public class DurableSubscriberExample {
    String      conFacName = null;
    String      topicName = null;
    static int  startindex = 0;

    /**
     * The DurableSubscriber class contains a constructor, a 
     * startSubscriber method, a closeSubscriber method, and a 
     * finish method.
     * 
     * The class fetches messages asynchronously, using a message
     * listener, TextListener.
     */
    public class DurableSubscriber {
        Context                    jndiContext = null;
        TopicConnectionFactory     topicConnectionFactory = null;
        TopicConnection            topicConnection = null;
        TopicSession               topicSession = null;
        Topic                      topic = null;
        TopicSubscriber            topicSubscriber = null;
        TextListener               topicListener = null;

        /**
         * The TextListener class implements the MessageListener
         * interface by defining an onMessage method for the
         * DurableSubscriber class.
         */
        private class TextListener implements MessageListener {
            final SampleUtilities.DoneLatch  monitor =
                new SampleUtilities.DoneLatch();

            /**
             * Casts the message to a TextMessage and displays 
             * its text. A non-text message is interpreted as the
             * end of the message stream, and the message
             * listener sets its monitor state to all done
             * processing messages.
             *
             * @param message    the incoming message
             */
            public void onMessage(Message message) {
                if (message instanceof TextMessage) {
                    TextMessage  msg = (TextMessage) message;
                    
                    try {
                        System.out.println("SUBSCRIBER: " +
                            "Reading message: " + msg.getText());
                    } catch (JMSException e) {
                        System.err.println("Exception in " + 
                            "onMessage(): " + e.toString());
                    }
                } else {
                    monitor.allDone();
                }
            }
        }

        /**
         * Constructor: looks up a connection factory and topic
         * and creates a connection and session.
         */
        public DurableSubscriber() {

            /* 
             * Create a JNDI API InitialContext object if none
             * exists yet.
             */
            try {
                jndiContext = new InitialContext();
            } catch (NamingException e) {
                System.err.println("Could not create JNDI API " +
                    "context: " + e.toString());
                System.exit(1);
            }
        
            /* 
             * Look up connection factory and topic.  If either
             * does not exist, exit.
             */
            try {
                topicConnectionFactory = (TopicConnectionFactory)
                    jndiContext.lookup(conFacName);
            } catch (NamingException e) {
                System.err.println("JNDI API lookup failed: " +
                    e.toString());
                System.exit(1);
            }
            
            try {
                topicConnection = 
                  topicConnectionFactory.createTopicConnection();
                topicSession = 
                    topicConnection.createTopicSession(false, 
                        Session.AUTO_ACKNOWLEDGE);
                topic = SampleUtilities.getTopic(topicName, 
                    topicSession);
            } catch (Exception e) {
                System.err.println("Connection problem: " +
                    e.toString());
                if (topicConnection != null) {
                    try {
                        topicConnection.close();
                    } catch (JMSException ee) {}
                }
    	        System.exit(1);
            } 
        }

        /**
         * Stops connection, then creates durable subscriber, 
         * registers message listener (TextListener), and starts
         * message delivery; listener displays the messages 
         * obtained.
         */
        public void startSubscriber() {
            try {
                System.out.println("Starting subscriber");
                topicConnection.stop();
                topicSubscriber = 
                    topicSession.createDurableSubscriber(topic,
                        "MakeItLast");
                topicListener = new TextListener();
               topicSubscriber.setMessageListener(topicListener);
                topicConnection.start();
            } catch (JMSException e) {
                System.err.println("Exception occurred: " + 
                    e.toString());
            }
        }
        
        /**
         * Blocks until publisher issues a control message
         * indicating end of publish stream, then closes 
         * subscriber.
         */
        public void closeSubscriber() {
            try {
                topicListener.monitor.waitTillDone();
                System.out.println("Closing subscriber");
                topicSubscriber.close();
            } catch (JMSException e) {
                System.err.println("Exception occurred: " + 
                    e.toString());
            }
        }
        
        /**
         * Closes the connection.
         */
        public void finish() {
            if (topicConnection != null) {
                try {
                    System.out.println("Unsubscribing from " +
                        "durable subscription");
                    topicSession.unsubscribe("MakeItLast");
                    topicConnection.close();
                } catch (JMSException e) {}
            }
        }
    }

    /**
     * The MultiplePublisher class publishes several messages to
     * a topic. It contains a constructor, a publishMessages
     * method, and a finish method.
     */
    public class MultiplePublisher {
        TopicConnection  topicConnection = null;
        TopicSession     topicSession = null;
        Topic            topic = null;
        TopicPublisher   topicPublisher = null;

        /**
         * Constructor: looks up a connection factory and topic
         * and creates a connection, session, and publisher.
         */
        public MultiplePublisher() {
            TopicConnectionFactory topicConnectionFactory = null;

            try {
                topicConnectionFactory = 
                    SampleUtilities.getTopicConnectionFactory();
                topicConnection = 
                  topicConnectionFactory.createTopicConnection();
                topicSession = 
                    topicConnection.createTopicSession(false, 
                        Session.AUTO_ACKNOWLEDGE);
                topic = 
                    SampleUtilities.getTopic(topicName, 
                        topicSession);
                topicPublisher = 
                    topicSession.createPublisher(topic);
            } catch (Exception e) {
                System.err.println("Connection problem: " + 
                    e.toString());
                if (topicConnection != null) {
                    try {
                        topicConnection.close();
                    } catch (JMSException ee) {}
                }
    	        System.exit(1);
            } 
        }
        
        /**
         * Creates text message.
         * Sends some messages, varying text slightly.
         * Messages must be persistent.
         */
        public void publishMessages() {
            TextMessage  message = null;
            int          i;
            final int    NUMMSGS = 3;
            final String MSG_TEXT =
                             new String("Here is a message");

            try {
                message = topicSession.createTextMessage();
                for (i = startindex; 
                         i < startindex + NUMMSGS; i++) {
                    message.setText(MSG_TEXT + " " + (i + 1));
                    System.out.println("PUBLISHER: Publishing " +
                        "message: " + message.getText());
                    topicPublisher.publish(message);
                }

                /*
                 * Send a non-text control message indicating end
                 * of messages.
                 */
            topicPublisher.publish(topicSession.createMessage());
                startindex = i;
            } catch (JMSException e) {
                System.err.println("Exception occurred: " + 
                    e.toString());
            }
        }
        
        /**
         * Closes the connection.
         */
        public void finish() {
            if (topicConnection != null) {
                try {
                    topicConnection.close();
                } catch (JMSException e) {}
            }
        }
    }
    
    /**
     * Instantiates the subscriber and publisher classes.
     * Starts the subscriber; the publisher publishes some
     *   messages.
     * Closes the subscriber; while it is closed, the publisher
     *   publishes some more messages.
     * Restarts the subscriber and fetches the messages.
     * Finally, closes the connections.    
     */
    public void run_program() {
        DurableSubscriber  durableSubscriber = 
                                         new DurableSubscriber();
        MultiplePublisher  multiplePublisher = 
                                         new MultiplePublisher();

        durableSubscriber.startSubscriber();
        multiplePublisher.publishMessages();
        durableSubscriber.closeSubscriber();
        multiplePublisher.publishMessages();
        durableSubscriber.startSubscriber();
        durableSubscriber.closeSubscriber();
        multiplePublisher.finish();
        durableSubscriber.finish();
    }

    /**
     * Reads the topic name from the command line, then calls the
     * run_program method.
     *
     * @param args    the topic used by the example
     */
    public static void main(String[] args) {
        DurableSubscriberExample  dse = 
                                  new DurableSubscriberExample();
        
        if (args.length != 2) {
    	    System.out.println("Usage: java " +
    	        "DurableSubscriberExample " +
    	        "<connection_factory_name> <topic_name>");
    	    System.exit(1);
    	}
    	dse.conFacName = new String(args[0]);
        System.out.println("Connection factory name is " + 
            dse.conFacName);
        dse.topicName = new String(args[1]);
        System.out.println("Topic name is " + dse.topicName);

    	dse.run_program();
    }
}