Jms using j boss
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The document is a comprehensive guide on Java Message Service (JMS) using JBoss, covering key concepts such as messaging domains, JMS architecture, and the basic building blocks of JMS applications. It details the steps necessary for writing JMS applications, configuring JBossMQ, and includes practical exercises to enhance understanding. Additionally, it provides references for further reading on JMS and JBossMQ functionalities.
Jms using j boss
- 2. Table Of Contents 2 Introduction to JMS JMS concepts JMS API Architecture JMS Application JBossMQ Getting started with JBossMQ
- 3. Introduction to JMS • Java Message Services, JMS, is Sun's standard API for message queuing systems. • JMS provides a flexible and powerful API that encourages a fine-grained, modular distribution of functionality among application components. • Why use JMS? • JMS has two message protocols: point to point and publisher/subscriber instead of only one, as many earlier middleware systems. • Asynchronous Messaging 3
- 4. Introduction to JMS (contd…) • Lose coupling, meaning reduced complexity as components depend less on each other. • Store-and-forward/Guaranteed delivery - Message is "held back" by the JMS provider in case receiver is not ready, and delivered as soon as the receiver is ready. • Quality of Service Enforcement - e.g. higher priority message delivered before low priority, drop old messages before they reach consumers etc. • Easy to learn programming model. 4
- 5. JMS concepts • A JMS provider is a messaging system that implements JMS and • provides administrative and control features. • JMS clients are the programs or components, written in the Java, • that produce and consume messages. • Messages are the objects that communicate information between • JMS clients. • Administered objects are preconfigured JMS objects created by an • administrator for the use of clients. • Two kinds of administered objects are Destinations and • Connection Factories. 5
- 6. Messaging Domains • Point-to-Point (PTP) • The Point-to-Point model calls the destination objects ‘queues’. • Each message has only one consumer. • Each queue can have multiple consumers. • A sender and receiver have no time dependencies. • The receiver acknowledges the successful processing of a message. • Use PTP when every message you send must be processed • successfully by one consumer. 6
- 7. Messaging Domains (contd…) • Publish/Subscribe The Pub-Sub model, calls the destination objects ‘topics’. • Each message may have multiple consumers. • Publishers and subscribers have timing dependencies. • Publishers and subscribers are generally anonymous and the system takes care of distributing the messages. 7
- 8. Message Consumption • Messages can be consumed in either of two ways: • Synchronously: A subscriber or a receiver explicitly fetches the message from the destination by calling the receive method. The receive method can block until a message arrives or can time out if a message does not arrive within a specified time. • Asynchronously: A client can register a message listener with a consumer. A message listener is similar to an event listener. Whenever a message arrives at the destination, the JMS provider delivers the message by calling the listener’s onMessage() method, which acts on the contents of the message. 8
- 9. JMS API Architecture • 1: Bind destinations and connection factories objects. • 2. Client looks up for administered objects in the namespace. • 3. Establish a logical connection to the looked up object • through a JMS provider. 9
- 10. The basic building blocks of a JMS application 10
- 11. The basic building blocks of a JMS application (contd…) • Administered Objects: Connection Factories: A connection factory is the object a client uses to create a connection with a provider Destinations: A destination is the object a client uses to specify the target of messages it produces and the source of messages it consumes • Sessions: A session is a single-threaded context for producing and consuming messages. You use sessions to create message producers, message consumers, and messages. • Message Producers:A message producer is an object created by a session and is used for sending messages to a destination. 11
- 12. The basic building blocks of a JMS application (contd…) • Message Consumers:A message consumer is an object created by a session and is used for receiving messages sent to a destination. • Messages • A JMS message has three parts: • A Header • Properties (optional) • A Body (optional) 12
- 13. Basic Steps for writing a JMS application • Get the JNDI initial context. • Look up a connection factory (for the right type of destination, topic or queue). • Obtain a connection from the factory. • Create a session tied to the connection. • Look up the destination (topic or queue). • Create a message producer or a message consumer (specific for the topic or the queue). 13
- 14. Basic Steps • 1) Get the JNDI initial context • Create a file named jndi.properties with the following lines: • Client jndi.properties file example: • java.naming.factory.initial=org.jnp.interfaces.NamingCont extFactory java.naming.provider.url=localhost:1099 java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.int erfaces • // Get the initial context • Context context = new InitialContext(); 14
- 15. Basic Steps (contd…) • 2) Look up a connection factory • For Topic • TopicConnectionFactory topicFactory = (TopicConnectionFactory) context.lookup("ConnectionFactory"); • For Queue • QueueConnectionFactory queueFactory = (QueueConnectionFactory)context.lookup("Connec tionFactory"); 15
- 16. Basic Steps (contd…) • 3) Obtain a connection from the factory • For Topic • TopicConnection topicConnection = topicFactory.createTopicConnection(); • • For Queue • QueueConnection queueConnection = • queueFactory.createQueueConnection(); 16
- 17. Basic Steps (contd…) • 4) Create a session tied to the connection • For Topic • TopicSession topicSession = • topicConnection.createTopicSession(false, • Session.AUTO_ACKNOWLEDGE); • For Queue • QueueSession queueSession = • queueConnection.createQueueSession(false, • Session.AUTO_ACKNOWLEDGE); • 17
- 18. Basic Steps (contd…) • 5) Look up the destination • For Topic • Topic topic = (Topic)context.lookup("topic/testTopic"); • For Queue • Queue queue = (Queue)context.lookup("queue/testQueue"); • Note: that in JBossMQ the prefix topic/ is always placed before • the topic name and the prefix queue/ is always placed before • the queue name. • 18
- 19. Basic Steps (contd…) • 6) Create a message producer • For Topic create publisher • TopicPublisher topicPublisher = topicSession.createPublisher(topic); • For Queue create sender • QueueSender queueSender = queueSession.createSender(queue); 19
- 20. Basic Steps (contd…) • 7) Create a TextMessage • For Topic create TextMessage and publish it • TextMessage message = topicSession.createTextMessage(); • message.setText(message); • topicPublisher.publish(topic, message); • For Queue create TextMessage and send it • TextMessage message = queueSession.createTextMessage(); • message.setText(message); • queueSender.send(queue, message); 20
- 21. Basic Steps (contd…) • 8) Create a message consumer • For asynchronous receiving implement a Message Listener • interface. • public class HelloSubscriber implements MessageListener { • Create and start a topic subscriber • topicSubscriber = topicSession.createSubscriber(topic); • • // Set the message listener • topicSubscriber.setMessageListener(this); • topicConnection.start(); • • 21
- 22. Basic Steps (contd…) • Create and start a queue receiver • queueReceiver = queueSession.createReceiver(queue); • // Set the message listener • queueReceiver.setMessageListener(this); • queueConnection.start(); 22
- 23. JBossMQ • JBossMQ is composed of several services working together to provide JMS API level services to client applications. • JBoss-4.x supports the JMS1.1 version spec. • JBoss-3.2.x supports the JMS1.0.2b spec. • It Supports two messaging styles: • Queue: a message is received by only one client. • Topic: a message is “broadcast” to multiple client subscribers. 23
- 24. Features of JBossMQ • Asynchronous delivery of messages. • Guaranteed delivery of message either by persisting the message or by redelivering it. • Multi protocol support. • Pluggable Security to support different security mechanisms. • Pluggable Persistence to support different persistence mechanisms. 24
- 25. Configuring JMS with JBoss 1. Install the JMS service This is a JMS folder in the deploy directory with *-service.xml MBean configurations 2. JMS Topics and Queues are implemented as MBeans 3. DestinationManager MBean manages the destinations (queue and topic) 4. The jbossmq-destinations-service.xml defines some default queues and topics 5. To add a new Queue (or topic), add a new entry like this to this file ( or any *-service.xml file) – • <mbean code="org.jboss.mq.server.jmx.Queue" • name="jboss.mq.destination:service=Queue,name=MyQueu e"> • </mbean> • This will add a queue by name ‘queue/MyQueue’ 25
- 26. Running the examples • For Topic 1) Start the Jboss Server. 2) Run the subscriber. 3) Run the publisher. • For Queue 1) Start the Jboss Server. 2) Run the sender. 3) Run the receiver. 26
- 27. JBoss MQ – Exercise -1 • Configure the queues ‘queue/inputQueue’ and ‘queue/outputQueue’ to the JBoss Server • Write a program to send java expression strings to the queue. • For e.g., the program could send the following strings “int a=1”, “int b=5”, and “int c=a+b” . This program then waits on the output queue and print the result once it is available. • Write a program to receive java expressions from the input queue and evaluate the expression and send the result to the output queue. (Use bsh shell for Java Expression Evaluation) 27
- 28. JBoss MQ – Exercise - 2 • Write a program to serialize an object and put it in a queue. • Write a program to receive serialized class files from a queue, de-serialize the object and execute methods on the object using Java reflection. 28
- 29. JBoss MQ – Exercise - 3 • Explore persistent messages with JBossMQ • Explore users/roles with JBossMQ 29
- 30. References • http://java.sun.com/products/jms/tutorial/1_3_1-fcs/doc/basics.html • http://www.coredevelopers.net/library/jboss/jms-dev/j2ee-container.jsp • http://docs.jboss.org/jbossas/jboss4guide/r3/html/ • http://www.jboss.org/wiki/Wiki.jsp?page=JBossMQ 30