SOA is an idea, not a technology.

True, SOA (service-oriented architecture) builds on the stack of protocols that define Web services, but it is hardly limited to that stack and draws as much on time-honored notions of business “re-engineering” as it does on XML, SOAP, and WSDL. Simply put, SOA is a broad, standards-based framework in which services are built, deployed, managed, and orchestrated in pursuit of new and much more agile IT infrastructures that respond swiftly to shifting business demands.

The breadth of that vision is what makes SOA seem so maddeningly vague. Nonetheless, the potential benefits of reduced IT costs and greater business agility have spurred many organizations to start down the path to SOA, to the point where most large enterprises now have some sort of SOA initiative under way. One reason for that extraordinary traction: SOA may ultimately have a transformative effect on the entire enterprise, but in contrast to other “big bang” endeavors, most of the applications and infrastructure you’ve already deployed can remain in place.

Throughout the past two years, InfoWorld has interviewed countless enterprise architects, developers, and officers who are guiding their organizations toward SOA deployment -- and who are learning hard lessons, gaining insight, and encountering infuriating technology gaps along the way. Many are already enjoying SOA’s early benefits of easy integration and code reusability. Based on their experiences, and the advice of industry technologists and analysts, we offer this step-by-step guide to planning, building, deploying, and managing an SOA.

As you’ll see, SOA provokes many of the same questions that dog most grand IT schemes. Should you buy and deploy SOA-related technology from a single vendor with which you already have a close relationship, or should you mix and match best-of-breed solutions? And, as with any standards-based initiative, what do you do when many of the standards necessary to achieve the real benefits aren’t fully cooked yet?

Such questions lack easy answers, and missing pieces of technology, industry disagreements, and vendor lock-in all threaten to dampen SOA’s much-ballyhooed benefit of hyperagility. Nonetheless, you’ll find most of the key concepts underlying SOA, a number of which may be familiar, right here -- although not necessarily in exactly the right order for you. Just as with SOA itself, how you put it all together depends on what you’ve got and where you want to go.