Joe McKendrick over at ZDNet has been pondering CIO "SOA Advisor" Nicholas Petreley's definition of SOA:

a networked subroutine

No wonder Joe's not sure about it! Nicholas' definition is closer to that of a web service and even that's being generous!

Joe rightly points out that the definition completely ignores the 'A' of SOA and comes up with his own alternative to address that limitation:

an architecture of services

But that suggests that SOA is something that you build—an end-product. It isn't. Architects in the real world don't create architecture: they do it! That's why they are called architecture practices.

Back in May 2005 in our first report on SOA, which set out to provide a big picture view of SOA, we proposed the following definition:

SOA is the disciplined approach through which an IT organisation manages the lifecycle of IT services, and assures their delivery, in a way the reflects business process priorities

As our SOA definition suggests, we see the ultimate value of SOA as shaping a service-oriented perspective on IT delivery, from top to bottom in the IT organisation. Service orientation can apply just as much to business architecture as it can to solution and technical architecture. It may not be quite as simple as Nicholas' definition but I think it more accurately reflects how thinking about SOA has moved on since the heady days of "SOA as software development and integration based on web services"