News

IBM Patterns for SOA

• By John K. Waters
• August 1, 2005

IBM is billing the software development patterns just published on its developerWorks Web site as the first designed to assist in the creation of service-oriented architectures.

The six new patterns, grouped as the WebSphere Platform Messaging Patterns Asset, focus on Enterprise Service Bus connectivity using the new messaging engine in IBM's WebSphere Application Server 6.0. They include well-known mediation patterns, such as message logging and message transformation, as well as topology patterns for configuring the service integration bus and message queues.

"ESB is the heart of SOA," says Angel Diaz, director of on-demand software development in IBM's Software Group. "An ESB can support the SOA goals of shared services and reuse, and help to eliminate the task of managing service interactions."

The patterns are packaged as reusable assets that can be imported and installed into the company's Rational Software Architect development environment. Users launch the RAS Asset Explorer and connect to the Rational XDE Repository. The URL is accessible only through the RAS Asset Explorer, not from a Web browser.

In software development, a pattern is the description of a recurring solution to a standard problem. Collections of interrelated patterns are called pattern languages, which, though not formal languages, provide a vocabulary for talking about a particular problem. As a literary form, patterns have required developers to manually implement code according to the pattern guidelines. IBM is eliminating the pencil-and-paper process by creating a repository of coded patterns accessed through the RSA tool.

The six new patterns include:

- Message Delegate: creates a client to send a message over JMS
- Message Logger Mediation: logs messages into database for audit purposes
- XSLT Mediation: transforms message from one format to another using an XSLT stylesheet
- Mediaton List Handler: configures a list of mediations that can be invoked in a sequence
- Service Integration Bus: configures the bus resources on WebSphere V6.0
- JMS Connection: configures JMS resources on WebSphere 6.0

IBM's first group of coded development patterns, called the Enterprise Patterns Asset, was published earlier this summer. Since then, the company has built a new site within developerWorks dedicated to patterns.

"We're building a community around patterns," says Grant Larsen, model driven development strategist for IBM Rational. "You're going to see more and more patterns released on the site, and not just from IBM."

The first software patterns were written by object-oriented developers in the 1990s, but they have roots in a design movement of the same name in contemporary architecture. The idea grew out of the writings of architect Christopher Alexander, who published several books on urban planning and building architecture. Patterns were brought to the attention of the developer community in 1995 with the publication of Design Patterns: Elements of Reusable Object-Oriented Software, by Erich Gamma, Richard Helm, Ralph Johnson and John Vlissides (best known today as The Gang of Four).

The new patterns are available as free downloads from the developerWorks Pattern Solutions Web site. The newly launched site, which IBM hopes will become a one-stop shop for its growing patterns community, lists the latest patterns, including source code, and provides links to a patterns resource center, with content to help organizations with their pattern-based development. It's located at: IBM.