Patterns: Broker Interactions for Intra- and Inter-enterprise

140 Broker Interactions for Intra- and Inter-enterprise

򐂰 It leverages existing, enterprise-proven messaging systems.

򐂰 It allows you to extend existing message-based applications by adding new

JMS clients that are integrated fully with their existing non-JMS clients.

򐂰 Developers have to learn only one common interface for accessing diverse

messaging systems.

7.5.4 Disadvantages of JMS

Though JMS provides a common interface for Java applications to interact with

messaging systems, it might lose out on some specific functionality offered by

the messaging vendor. In that case, you might still have to write vendor-specific

code to access such functionality.

JMS only provides asynchronous messaging, so the design is more complex

when addressing response correlation, error handling, and data synchronization.

Further information on JMS can be found in the IBM Redbook MQSeries

Programming Patterns, SG24-6506.

7.6 Message Oriented Middleware

The Message Oriented Middleware (MOM) consists of a transport layer that

deals with the communication (physical) aspects of moving messages between

the origination and the destination points. It takes care of the networking protocol

issues, the message encoding and even translation. It is said to encapsulate the

business of transporting message. At the same time, it provides APIs to enable

application to manipulate (send/receive) messages. It is obviously a very critical

and absolutely necessary part of the messaging-based integration layer.

The transport layer, per se, does not do any message transformation or handle

message routing.

From the integration layer perspective, such basic messaging systems offer

limited value. They were therefore enriched with the additional functionality of

handling the transformation and containing dynamic routing capabilities. This in

turn evolved even further to support not only point-to-point distribution but also

publish/subscribe style scenarios and handling of the complex message flows.

The messaging system components providing this functionality are commonly

known as the message brokers, for example, WebSphere MQ.