JMS_Guide-20020611

What is JMS API?
The Java Message Service is a Java API that allows applications to create, send, receive, and read messages. The JMS API enables communication that is not only loosely coupled but also Asynchronous A JMS provider can deliver messages to a client as they arrive; a client does not have to request messages in order to receive them. Reliable The JMS API can ensure that a message is delivered once and only once. Lower levels of reliability are available for applications that can afford to miss messages or to receive duplicate messages.
JMS API
TopicPublisher TopicSession MessageProducer QueueSender Session TopicSubscriber QueueSession MessageConsumer QueueReceiver LEGEND Inheritance (Extend) Message Flow
JMS API Architecture
• Administrative tools allow you to bind destinations and connection factories into a Java Naming and Directory Interface TM (JNDI) API namespace. • A JMS client can then look up the administered objects in the namespace and then establish a logical connection to the same objects through the JMS provider. JNDI NameSpace
Subscriber2
msg n
msg 7 : msg 6 : msg 5 msg 7 msg 6 msg 4 msg 5 msg 3 msg 4 2 msg 1 msg 3
msg 2 msg 1
: : msg n ::
consume
consume Subscriber1
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Persistence and no-persistence message delivery no-
Administration Tool
bind
CF
N
JMS Client
Logic connection
JMS Provider
Relationship ------ JMS Provider, App Server, App
JMS Provider Server Session implements implements delivers messages to
Publisher3
publish
Publisher2
publish
Publisher1
Publisher1
msg n
msg n
consume
Subscriber2
msg 7 msg 6 msg 6 msg 5 msg 5 msg 4 msg 4 msg 3 msg 2 msg 3 msg 2 msg 1
Producer JMS Server Subscriber
JMS Message
A JMS message has three parts: A header Properties (optional) A body (optional)
Header Field JMSDestination JMSDeliveryMode JMSExpiration JMSPriority JMSMessageID JMSTimestamp JMSCorrelationID JMSReplyTo JMSType JMSRedelivered Set By send or publish method send or publish method send or publish method send or publish method send or publish method send or publish method Client Client Client JMS provider
JMS Specifications - Topics
• Publisher publishes and publish Publisher3 Subscribers consumes publish • Multiple Publisher1 Publisher2 publishers/subscribers per topic • Subscriber each receives own Publisher1 copy of messages consume • Priority effects message delivery order • Persistent and non-persistent delivery semantics
Connection Consumer
implements
App Server
control thread for
message a pool of
implements
Session Server Session Pool get a ServerSession from
delivers messages to
Properties
Body
The payload of the Message (one of five types)
JMS Message Type
ObjectMessage
MapMessage
Message
StreamMessage
TextMessage
XMLMessage
ByteMessage
is delivered messages for Destination With optional message selector supplies
Message Listener
implements App
Objects
ConnectionFactory - an administered object used by a client to create a Connection Connection - an active connection to a JMS provider Destination - an administered object that encapsulates the identity of a message destination Session - a single-threaded context for sending and receiving messages MessageProducer - an object created by a Session that is used for sending messages to a destination MessageConsumer - an object created by a Session that is used for receiving messages sent to a destination
JMS API Programming Model
Connection Factory
creates
Connection
creates
JMS
Next Generation Integration Platform
hJMS消息中间件开源项目 founder_chen@ 2002-06-03
JMS specification
Two message Models queues, topics Persistence and no-persistence message delivery noFive message types – text, byte, object, map and stream Synchronous and Asynchronous message consumption Selector, priority, queueBrowser Local and distributed transaction
Structure of JMS Message
Message Header
Optional name/value pairs, Can be use to filter messages Various standard flags for routing, identification, expiration etc.
msg 7
: :: :::
consume
consume
Subscriber1
msg 1
Subscriber1
P/S Messaging Domain
Each message may have multiple consumers. Publishers and subscribers have a timing dependency. A client that subscribes to a topic can consume only messages published after the client has created a subscription, and the subscriber must continue to be active in order for it to consume messages.