JAXM & Messaging

JAXM Definition

JAXM, the Java API for XML Messaging, defines a lightweight Java API for composing, processing, sending, and receiving XML documents. It supports both synchronous (HTTP) and asynchronous (SMTP) messaging and “Out-of-the-box” support for ebXML messaging.

Fundamental Elements

The JAXM Service

A JAXM service consumes JAXM messages sent by a JAXM client. To develop a JAXM service, developers extend the class javax.xml.messaging.JAXMServlet and implement either the javax.xml.messaging.OnewayListener or javax.xml.messaging.ReqRespListener interface. The choice of interface depends upon whether the interaction between the client and the server is asynchronous (OnewayListener) or synchronous (ReqRespListener) in nature.

The JAXM Client

Clients exchange messages with JAXM services. JAXM clients can either interact directly with a JAXM service or go through a JAXM provider. JAXM clients that interact directly with a JAXM service can only participate in synchronous interactions. JAXM clients that use a messaging provider can participate in asynchronous as well as synchronous interactions with the JAXM service.

The JAXM Messaging Provider

A JAXM messaging provider is responsible for managing the routing of messages for a JAXM client. Besides providing a degree of separation between a JAXM client and service, a provider can also offer additional services like reliable messaging, security, and transaction support. Currently, clients that want to interact asynchronously with a JAXM service have to use a provider.

The JAXM Message

All JAXM messages conform to the SOAP 1.1 and SOAP with Attachments standards. JAXM messages also support the concept of higher-level protocols like ebXML through the concept of messaging profiles. A messaging profile defines the messaging contract between two parties. A JAXM client and service that share a message profile like ebXML can conduct business by exchanging ebXML messages.

JAXM & Messaging

* JAXM is an synchronous / asynchronous (queue-based) messaging API
* Not part of J2EE 1.4
* Uses queues on either side
* Doesn’t provide WSDL facilities
* Can be used in conjunction with JAXB to convert to objects

Difference in JAXM & JMS

The JAXM API was designed for Internet SOAP-based messaging, while the JMS API was designed as a common messaging API to be layered over existing enterprise message-oriented middleware (MOM) applications.

The delivery endpoint models differ. JAXM provides direct point-to-point messaging, while JMS uses destinations to provide a reliable asynchronous messaging capability.

JMS clients send messages to, and retrieve them from, destinations. JMS provides a model whereby an intermediary, a messaging server, makes sure a message is delivered between two applications that do not know directly about each other, but know only about the common destination.

A JAXM client is interoperable over any SOAP 1.1 compatible client (there must be an agreed-upon profile between providers, however), whereas a JMS client is interoperable only with other JMS clients over the same messaging system (or another messaging system for which the JMS provider supports a proprietary gateway).

The JMS API does not define interoperability between message providers. It does not define a common message format, only a number of message types; the clients must agree on the precise format. (It is possible to wrap a SOAP message, or any other kind of XML message, in a TextMessage and send it via JMS.)

Find out more info from JAXM FAQ

Why there is a need for JAXM?

The goal of JAXM is to provide a rich set of interfaces for document-style web services. Document-style web services enable the exchange of XML documents between two parties, as opposed to RPC-style web services, which expose software functions as web services.

JAXM-based web services can be used effectively in Such scenario:

When two parties want to exchange data using XML documents that are bounded using well-defined XML schemas instead of invoking software functions (Java objects, C procedures, etc.) exposed as RPC-style web services.

I would like to recommend you to go through a article called "Developing E-Business Interactions with JAXM" for a good understanding of How & Where to use JAXM

Implementation

Sun provides JAXM implementation, but does not support full ebXML messaging service specification, there is alternative implementation of ebMS 2.0 from www.freebxml.org.

ebXML & Message Service

Find more from my previous post here.
Find more from article called "ebXML Message Service - An In-depth Overview"

Reference List:

http://java.sun.com/webservices/jaxm
Sun JAXM tutorial
Developing E-Business Interactions with JAXM