-Explain the basics JMS - Use API of Java References YouTube link : https://www.youtube.com/playlist?list=PLtDIUAtyP4lhV7CsYfLuIx26UeG4J-ujZ GitHub : https://github.com/Ghadeerof

1. Distributed Systems
Lecture -7-
Created by :
Eng. Ghadeer Al Hasan
JMS
Java Message Service

2. Intro 1
• JMS (Java MessageService) is an API that provides the facilityto create, send and read messages.
• It provides looselycoupled, reliable and asynchronous communication.
• JMS is also known as a messaging service

3. Understanding Messaging 2
• Messaging is a technique to communicateapplications or software components.
• JMS is mainly usedto sendand receive messagefromone applicationto another.

4. Advantage of JMS 3
• Asynchronous: To receive the message, client is not required to send request. Message will arrive
automatically to the client.
• Reliable: It provides assurance that messageis delivered.

5. Messaging Domains 4
There are two types of messaging domains in JMS :
• Point-to-PointMessaging Domain
• Publisher/Subscriber Messaging Domain

6. Point-to-Point (PTP) Messaging Domain 5
• In PTP model, one message is delivered to one receiver only. Here, Queue is used as a message
oriented middleware (MOM).
• The Queue is responsible to hold the message until receiver is ready.
• In PTP model, there is no timing dependencybetween sender and receiver.

7. Publisher/Subscriber (Pub/Sub) Messaging Domain 7
• In Pub/Sub model, one message is delivered to all the subscribers. It is like broadcasting.
• Topicis used as a messageorientedmiddleware that is responsible to hold and deliver messages.
• In PTP model, there is timing dependency between publisher and subscriber.

8. JMS Programming Model 8

9. JMS Queue Example

10. 1st Create connection factory 9

11. 2nd Create destination resource 10

12. 3rd Create Sender application 11
InitialContext ctx = new InitialContext();
QueueConnectionFactory f = (QueueConnectionFactory) ctx.lookup("myQueueConnectionFactory");
QueueConnection con = f.createQueueConnection();
con.start();
QueueSession session = con.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);
Queue queue = (Queue) ctx.lookup("myQueue");
QueueSender sender = session.createSender(queue);
TextMessage msg = session.createTextMessage();

13. 3rd Create Sender application… 12
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
while(true) {
log("Enter Msg, end to terminate:");
String line = reader.readLine();
if (line.equals("end"))
break;
msg.setText(line);
sender.send(msg);
log("Message successfully sent.");
}

14. 4th Create Receiver application 13
public class MsgListener implements MessageListener {
@Override
public void onMessage(Message m) {
try {
TextMessage msg = (TextMessage) m;
log("following message is received:" + msg.getText());
} catch (JMSException e) {
log(e);
}
}
}

15. 4th Create Receiver application… 14
InitialContext ctx = new InitialContext();
QueueConnectionFactory f = (QueueConnectionFactory) ctx.lookup("myQueueConnectionFactory");
QueueConnection con = f.createQueueConnection();
con.start();
QueueSession session = con.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);
Queue queue = (Queue) ctx.lookup("myQueue");
QueueReceiver receiver=ses.createReceiver(queue);
MsgListener listener = new MsgListener();
receiver.setMessageListener(listener);
Log("Receiver is ready, waiting for messages...“);
while(true){
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
log(ex.getMessage());
}
}

16. References 15
- YouTube link
https://www.youtube.com/playlist?list=PLtDIUAtyP4lhV7CsYfLuIx26UeG4J-ujZ
- GitHub
https://github.com/Ghadeerof

17. End Lecture