1. J2EE Lecture 13: JMS and WebSocket
Dr. Ming Qiu
Xiamen University
Software School

2. 13.1 Introduction to MDB How to implement messaging
Mastering EJB3.0, Chap 7
13.1 Introduction to MDB
How to implement messaging
An overview of asynchronous behavior and message-oriented middleware (MOM)
How to use the Java Message Service(JMS),
MOM framework for JMS-based message-driven beans
The features of message-driven beans
Compared with entity and session beans
How to develop message-driven beans

3. 13.1 Introduction to MDB Motivations for Messaging
Mastering EJB3.0, Chap 7
13.1 Introduction to MDB
Motivations for Messaging
Several areas are challenging for RMI-IIOP
Asynchrony
Decoupling
Reliability
Support for multiple senders and receivers

4. Mastering EJB3.0, Chap 7
13.1 Introduction to MDB

5. EJB in Action, Chap 4
13.1 Introduction to MDB

6. 13.1 Motivations for Messaging
Mastering EJB3.0, Chap 7
13.1 Motivations for Messaging
Message-oriented middleware(MOM)
Tibco Rendezvous
IBM WebSphere MQ
BEA Tuxedo/Q
Sun Java System Messaging Server
Microsoft MSMQ
JBoss MQ
RabbitMQ
ActiveMQ

7. 13.2 The Java Message Service (JMS)
Mastering EJB3.0, Chap 7
13.2 The Java Message Service (JMS)
A messaging standard, which has two parts
an API
Write code to send and receive messages
A Service Provider Interface (SPI)
Plug in JMS provider
Know how to talk to specific MOM implementation

8. 13.2 The Java Message Service (JMS)

9. 13.2 The Java Message Service (JMS)
Message Domains
Publish/subscribe (pub/sub)

10. 13.2 The Java Message Service (JMS)
Point-to-point (PTP)

11. 13.2 The Java Message Service (JMS)
Mastering EJB3.0, Chap 7
13.2 The Java Message Service (JMS)
EJB in Action, Chap 4
JMS API
Locate the JMS Provider’s ConnectionFactory instance (javax.jms.ConnectionFactory)
Look it up in JNDI
Create a JMS connection (javax.jms.Connection)
A active connection to the JMS provider
Thread-safe and designed to be sharable
Create a JMS session (javax.jms.Session)
provides a single-threaded, task-oriented context for sending and receiving messages.

12. 13.2 The Java Message Service (JMS)
Mastering EJB3.0, Chap 7
13.2 The Java Message Service (JMS)
Locate the JMS Destination
The channel to which you’re sending or from with you’re receiving messages
Set up by deployer in advances
Looked up from JNDI
Create a JMS Producer or a JMS Consumer
JMS Producer
Call it to pass your message
JMS Consumer
Call it to ask for a message
Send or receive your message

13. Mastering EJB3.0, Chap 7

14. 13.2 The Java Message Service (JMS)
Mastering EJB3.0, Chap 7
13.2 The Java Message Service (JMS)

15. Mastering EJB3.0, Chap 7

16. 13.2 The Java Message Service (JMS)
Mastering EJB3.0, Chap 7
13.2 The Java Message Service (JMS)

17. 13.2 The Java Message Service (JMS)
EJB in Action, Chap 4
13.2 The Java Message Service (JMS)

18. 13.3 Working with MDB What is a Message-Driven Bean?
Mastering EJB3.0, Chap 7
13.3 Working with MDB
EJB in Action, Chap 4
What is a Message-Driven Bean?
EJB components designed to consume the asynchronous messages
Does not have a remote or local business interface
Support generic listener methods for message delivery
Called by an EJB container upon arrival of a message
Do not have return values and not send exceptions back to clients
Message-driven beans are stateless
Message-driven beans are single-threaded
The container is responsible for serializing messages
The container provide concurrent message consumption by pooling multiple message-driven beans

19. EJB in Action, Chap 4
13.3 Working with MDB

20. 13.4 Developing Message-Driven Beans
EJB in Action, Chap 4
13.4 Developing Message-Driven Beans
MDBs must follow these rules
Must implement javax.jms.MessageListener
Must be concrete. It cannot be either a final or an abstract class.
Must be a POJO class and not a subclass of another MDB.
Must be declared public.
Must have a no-argument constructor.
Cannot define a finalize method in the bean class.
Must not throw the javax.rmi.RemoteException or any runtime exceptions.

21. 13.4 Developing Message-Driven Beans
EJB in Action, Chap 4
13.4 Developing Message-Driven Beans

22. 13.4 Developing Message-Driven Beans
EJB in Action, Chap 4
13.4 Developing Message-Driven Beans

23. 13.4 Developing Message-Driven Beans
EJB in Action, Chap 4
13.4 Developing Message-Driven Beans

24. 13.4 Developing Message-Driven Beans
Mastering EJB3.0, Chap 7
13.4 Developing Message-Driven Beans

25. 13.4 Developing Message-Driven Beans
EJB in Action, Chap 4
13.4 Developing Message-Driven Beans
acknowledgeMode
Messages are not actually removed from the queue until the consumer acknowledges them.

26. 13.4 Developing Message-Driven Beans
EJB in Action, Chap 4
13.4 Developing Message-Driven Beans
subscriptionDurability
specify whether the topic subscription is durable or nondurable
durable subscription
all messages sent to the topic are guaranteed to be delivered to that consumer

27. Spring Framework Doc
13.5 Spring JMS
Provides a JMS integration framework that simplifies the use of the JMS API
JmsTemplate
Message-Driven POJOS (MDPs)

28. 13.5 Spring JMS Sending a Message - JmsTemplate
Spring Framework Doc
13.5 Spring JMS
Sending a Message - JmsTemplate
the central class in the JMS core package
Requires a reference to a ConnectionFactory.
ConnectionFactory is used by the client application as a factory to create connections with the JMS provider and encapsulates various configuration parameters.

29. Spring Framework Doc

30. Spring Framework Doc
13.5 Spring JMS

31. Spring Framework Doc
13.5 Spring JMS

32. Spring Framework Doc
13.5 Spring JMS

33. Spring Framework Doc

34. Spring Framework Doc
13.5 Spring JMS
Receiving a Message - MDPs

35. Spring Framework Doc
13.5 Spring JMS

36. 13.6 WebSocket
HTTP Protocol

37. 13.6 WebSocket
HTTP Protocol

38. 13.6 WebSocket
WebSocket is a protocol which communicates between browser and web server.
works over TCP protocol.
opens a socket connection between browser and web server and start communication.

39. 13.6 WebSocket

40. 13.6 WebSocket
SockJS is a java script library which provides websocket like object for browsers.
provides cross browser compatibility and supports STOMP protocol to communicate with any message broker.
works in the way that we need to provide URL to connect with message broker and then get the stomp client to communicate.

41. 13.6 WebSocket STOMP is Streaming Text Oriented Messaging Protocol.
A STOMP client communicates to a message broker which supports STOMP protocol.
STOMP uses different commands like connect, send, subscribe, disconnect etc to communicate.

42. 13.6 WebSocket
Configuration Class to Support Spring 4 WebSocket

43. 13.6 WebSocket

44. 13.6 WebSocket @EnableWebSocketMessageBroker
enables a configuration class to support WebSocket
AbstractWebSocketMessageBrokerConfigurer is extended by WebSocket Configuration class

45. 13.6 WebSocket MessageBrokerRegistry helps to register message broker.
topic : there are more than one subscribers for a message.
queue : peer to peer communication.
StompEndpointRegistry register an end point for the STOMP over WebSocket.

46. 13.6 WebSocket
Controller class for WebSocket

47. 13.6 WebSocket
STOMP Client

48. 13.6 WebSocket

49. 13.6 WebSocket

50. 13.6 WebSocket

51. 13.6 WebSocket

52. 13.6 WebSocket
The return value from method is converted with a MessageConverter and used as the body of a new message that is then sent, by default, to the "brokerChannel" with the same destination as the client message but using the prefix "/topic" by default.
message level annotation can be used to specify any other destination instead.

54. 13.6 WebSocket
Flow of Messages