This tutorial explains how to configure and run some JMS destinations using a managed JMS environment.

1. SKILLWISE-JMS
USING JBOSS

2. Table Of Contents
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 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
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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.
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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.
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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.
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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.
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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.
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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.
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10. The basic building blocks of a JMS application
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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.
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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)
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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).
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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();
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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");
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16. Basic Steps (contd…)
• 3) Obtain a connection from the factory
• For Topic
• TopicConnection topicConnection =
topicFactory.createTopicConnection();
•
• For Queue
• QueueConnection queueConnection =
• queueFactory.createQueueConnection();
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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);
•
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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.
•
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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);
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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);
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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();
•
•
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22. Basic Steps (contd…)
• Create and start a queue receiver
• queueReceiver =
queueSession.createReceiver(queue);
• // Set the message listener
• queueReceiver.setMessageListener(this);
• queueConnection.start();
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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.
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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.
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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’
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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.
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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)
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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.
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29. JBoss MQ – Exercise - 3
• Explore persistent messages with
JBossMQ
• Explore users/roles with JBossMQ
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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
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