Service-Oriented Architecture (SOA) is no longer new. Five years ago, a few advanced thinkers were exploring the concept. Enterprises started experimenting with pilot projects. They liked the results. Interest and enthusiasm grew, and led to wider deployment. Now, most enterprises are planning to do something with SOA, and the early adopters are into their second or third phase developments. Everyone is asking, "How will SOA affect my enterprise?" But a better question for CEOs and CIOs to ask might be, "How will I change my enterprise to take advantage of SOA?"

SOA is a style of enterprise architecture that is radically different from earlier styles. This has led to some polarization among enterprise architects, with SOA devotees and traditional enterprise architects forming different communities. Indeed, David Linthicum, the well-known SOA expert and blogger, speaking at the recent Open Group conference in Austin, Texas, referred to them as "different tribes," which do not understand each other. There is truth in this comment. But the underlying reason is perhaps the difference between architects that have been through the SOA experience and those that have yet to do so, rather than any issue of architectural good practice. SOA has significant implications for the architect, which are really appreciated and understood only by doing it.

But SOA is not just a matter for architects. It has wider implications within the enterprise, impacting on the way that some operations are organized. And, conversely, overall enterprise organization can impact on SOA. These are matters for the CIO and the CEO. Their decisions can make the difference between an enterprise that benefits from the business agility that SOA can bring, and one that struggles to come to terms with the technology.

These decisions should be based on an understanding of what SOA is, of its implications for the way that the enterprise works, and of how operations involving SOA should be governed.

Why SOA Is Different
What distinguishes SOA from traditional approaches to enterprise architecture? This question is explored in a recently published Open Group White Paper on Service-Oriented Architecture. Here is a summary:

The principle of service orientation can apply throughout an enterprise architecture, but is usually applied to the organisation of the software that supports the enterprise's business operations. With SOA, this software is organised as a set of loosely-coupled software services. The services are supported by an infrastructure that, together with the services, enables information to flow freely within the enterprise and between the enterprise and external organizations.