PS:
1. implements MessageListener
2. create TopicConnection [using jndi]
3. create two session
4. create publisher and subscriber
5. set listener
6. connection start() , publisher.publish(message), onMessage()
7. connection close()
package jms.chat;

import javax.jms.*;
import javax.naming.*;
import java.io.*;
import java.io.InputStreamReader;
import java.util.Properties;


public class Chat implements MessageListener ...{
private TopicSession pubSession;

private TopicSession subSession;

private TopicPublisher publisher;

private TopicConnection connection;

private String username;


/**//* Constructor. Establish JMS publisher and subscriber */
public Chat(String topicName, String username, String password)

throws Exception ...{
// Obtain a JNDI connection
Properties env = new Properties();
// ... specify the JNDI properties specific to the vendor
InitialContext jndi = new InitialContext(env);
// Look up a JMS connection factory
TopicConnectionFactory conFactory = (TopicConnectionFactory) jndi
.lookup("TopicConnectionFactory");
// Create a JMS connection
TopicConnection connection = conFactory.createTopicConnection(username,
password);
// Create two JMS session objects
TopicSession pubSession = connection.createTopicSession(false,
Session.AUTO_ACKNOWLEDGE);
TopicSession subSession = connection.createTopicSession(false,
Session.AUTO_ACKNOWLEDGE);
// Look up a JMS topic
Topic chatTopic = (Topic) jndi.lookup(topicName);
// Create a JMS publisher and subscriber
TopicPublisher publisher = pubSession.createPublisher(chatTopic);
TopicSubscriber subscriber = subSession.createSubscriber(chatTopic);
// Set a JMS message listener
subscriber.setMessageListener(this);
// Intialize the Chat application
set(connection, pubSession, subSession, publisher, username);
// Start the JMS connection; allows messages to be delivered
connection.start();
}


/**//* Initialize the instance variables */
public void set(TopicConnection con, TopicSession pubSess,

TopicSession subSess, TopicPublisher pub, String username) ...{
this.connection = con;
this.pubSession = pubSess;
this.subSession = subSess;
this.publisher = pub;
this.username = username;
}


/**//* Receive message from topic subscriber */

public void onMessage(Message message) ...{

try ...{
TextMessage textMessage = (TextMessage) message;
String text = textMessage.getText();
System.out.println(text);

} catch (JMSException jmse) ...{
jmse.printStackTrace();
}
}


/**//* Create and send message using topic publisher */

protected void writeMessage(String text) throws JMSException ...{
TextMessage message = pubSession.createTextMessage();
message.setText(username + " : " + text);
publisher.publish(message);
}


/**//* Close the JMS connection */

public void close() throws JMSException ...{
connection.close();
}


/**//* Run the Chat client */

public static void main(String[] args) ...{

try ...{
if (args.length != 3)
System.out.println("Topic or username missing");
// args[0]=topicName; args[1]=username; args[2]=password
Chat chat = new Chat(args[0], args[1], args[2]);
// Read from command line
BufferedReader commandLine = new java.io.BufferedReader(
new InputStreamReader(System.in));
// Loop until the word "exit" is typed

while (true) ...{
String s = commandLine.readLine();

if (s.equalsIgnoreCase("exit")) ...{
chat.close(); // close down connection
System.exit(0);// exit program
} else
chat.writeMessage(s);
}

} catch (Exception e) ...{
e.printStackTrace();
}
}
}
