Java Message Service

The Java Message Service (JMS) API is a Java Message Oriented Middleware (MOM) API[1] for sending messages between two or more clients. It is an implementation to handle the Producer-consumer problem. JMS is a part of the Java Platform, Enterprise Edition, and is defined by a specification developed under the Java Community Process as JSR 914.[2] It is a messaging standard that allows application components based on the Java Enterprise Edition (Java EE) to create, send, receive, and read messages. It allows the communication between different components of a distributed application to be loosely coupled, reliable, and asynchronous.[3]

General idea of messaging

Messaging is a form of loosely coupled distributed communication, where in this context the term 'communication' can be understood as an exchange of messages between software components. Message-oriented technologies attempt to relax tightly coupled communication (such as TCP network sockets, CORBA or RMI) by the introduction of an intermediary component. This approach allows software components to communicate 'indirectly' with each other. Benefits of this include message senders not needing to have precise knowledge of their receivers.

The advantages of messaging include the ability to integrate heterogeneous platforms, reduce system bottlenecks, increase scalability, and respond more quickly to change.[4]

Version history

JMS 2.0 is maintained under the Java Community Process as JSR 343.

Elements

The following are JMS elements:[3]

JMS provider
An implementation of the JMS interface for a Message Oriented Middleware (MOM). Providers are implemented as either a Java JMS implementation or an adapter to a non-Java MOM.
JMS client
An application or process that produces and/or receives messages.
JMS producer/publisher
A JMS client that creates and sends messages.
JMS consumer/subscriber
A JMS client that receives messages.
JMS message
An object that contains the data being transferred between JMS clients.
JMS queue
A staging area that contains messages that have been sent and are waiting to be read (by only one consumer). Contrary to what the name queue suggests, messages don't have to be received in the order in which they were sent. A JMS queue only guarantees that each message is processed only once.
JMS topic
A distribution mechanism for publishing messages that are delivered to multiple subscribers.

Models

The JMS API supports two models:

Point-to-point model

In the point-to-point messaging system, messages are routed to an individual consumer which maintains a queue of "incoming" messages. This messaging type is built on the concept of message queues, senders, and receivers. Each message is addressed to a specific queue, and the receiving clients extract messages from the queues established to hold their messages. While any number of producers can send messages to the queue, each message is guaranteed to be delivered, and consumed by one consumer. Queues retain all messages sent to them until the messages are consumed or until the messages expire. If no consumers are registered to consume the messages, the queue holds them until a consumer registers to consume them.

Publish/subscribe model

The publish/subscribe model supports publishing messages to a particular message topic. Subscribers may register interest in receiving messages on a particular message topic. In this model, neither the publisher nor the subscriber knows about each other. A good analogy for this is an anonymous bulletin board

JMS provides a way of separating the application from the transport layer of providing data. The same Java classes can be used to communicate with different JMS providers by using the Java Naming and Directory Interface (JNDI) information for the desired provider. The classes first use a connection factory to connect to the queue or topic, and then use populate and send or publish the messages. On the receiving side, the clients then receive or subscribe to the messages.

URI scheme

RFC 6167 defines a jms: URI scheme for the Java Message Service.

Provider implementations


To use JMS, one must have a JMS provider that can manage the sessions, queues and topics. Starting from Java EE version 1.4, JMS provider has to be contained in all Java EE application servers. This can be implemented using the message inflow management of the Java EE Connector Architecture, which was first made available in that version.

The following is a list of JMS providers:

A historical comparison matrix of JMS providers from 2005 is available at http://www.theserverside.com/reviews/matrix.tss

See also

The Wikibook Java EE Programming has a page on the topic of: Java Message Service

References

  1. ↑ Curry, Edward. 2004. "Message-Oriented Middleware". In Middleware for Communications, ed. Qusay H Mahmoud, 1-28. Chichester, England: John Wiley and Sons. doi:10.1002/0470862084.ch1. ISBN 978-0-470-86206-3
  2. ↑ JSR914 - JMS Spec
  3. 1 2 Java Message Service (JMS)
  4. ↑ Richards et al, pages 3-5
  5. ↑ "Apache Qpid™: Open Source AMQP Messaging".
  6. ↑ Wallis, Graham. "Choosing a messaging system: WebSphere MQ vs. the WebSphere Application Server Service Integration Bus". IBM developerWorks.

Further reading

External links

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