Going to the Max

Also known as adaptive architecture, SOA is extensible and dynamic, with a key focus on interoperability. As a design approach SOA breaks down monolithic applications into suites of services that are available to IT across the enterprise to promote maximum flexibility and value. The idea is to optimize technology investments and achieve tighter alignment by integrating existing systems, applications and users into a flexible architecture that can easily accommodate changing needs.

Using a SOA also makes it easier to anticipate both changed requirements and potential changes in business processes. Flexibility is the name of the game.

Implemented as a collection of loosely coupled reusable services on a network that communicate with one another asynchronously and have well-defined, platform-independent interfaces, a SOA allows greater reuse of IT assets and greater adaptability to support ongoing change. As a higher level of application development it helps mask the underlying technical complexity of the IT environment by focusing on business processes and using standard interfaces. Enterprise resource planning (ERP) systems are dissolved in favour of self-contained services performing specific business functions that can be invoked over standard protocols to ensure their availability across the enterprise and beyond.

IT analysis firm Butler Group says while the majority of organizations have yet to take advantage of it, they should consider adopting a SOA as new applications are developed. The company says SOAs will have a significant effect on styles of development, with increased use of modelling and the application of patterns, and less emphasis on pure coding. They will also promote the use of Web services as the standard model of communication between application components.

Vendors say having a single standard all the major vendors support for packaging of software parts makes the idea of building large scale systems out of parts a reality for the first time in the history of computer science.

"I tend to think about it in terms of building software systems out of parts, and that's something that people have wanted to do for a long time because of course they do it in other industries like manufacturing and electronics, but in the world of computer science we've been behind the curve relative to most other industries in our ability to build systems out of parts," says WebMethods chief technology officer Graham Glass. "That's basically what SOA is all about: It's the idea of constructing systems out of parts. And one of the main problems and one of the main reasons people haven't been able to do that in the past is because there hasn't been a standard way to actually build a software part."

Consultant and IT analysis firm Meta Group says the new set of meta-architectural principles will be broadly diffused throughout the IT environment in the form of service-oriented business architecture, service-oriented security architecture and service-oriented management architecture by 2005. By 2006 it says SOA will be widely understood and treated as a metadata (or model) interoperability architecture, given its emphasis on interoperable identifiers (namespace metadata), formats (information models) and protocols (process models). By 2007, composite applications will be based on the SOA principles of dynamic, extensible, federated interoperability and enabled by XML-based technologies such as Web services.

However, Meta points out that in demanding a fundamental shift in the way organizations think about the construction and relationships implicit in their IT and business systems, SOA demands as profound a shift in thinking as client/server did several decades ago.

"This example is instructive; it took more than 15 years for client/server architectures and the associated design concepts to permeate industry at that time, and the SOA transition is unlikely to be simpler," writes Meta's Daniel Sholler. "SOA is reflected in changing ideas about how businesses are organized and should relate to each other. Put simply, it is a reflection of the long-term drive toward focus on core competencies and differentiation, and the associated trends toward outsourcing."