What's REALLY new about SOA?
Britton Manasco over
at ZDNet provides an insightful analysis of some recent commentary by Michael Liebow, VP of Web Services and SOA at IBM Global Services. Liebow's comments address the issue of what is new about SOA and, unsurprisingly, emphasises broad support (RESTafarians excepted, of course) for web services standards as the distinguishing factor. Whilst I don’t disagree with the importance of implementation-independent, interoperable, open standards, I do have a problem with the assumption which appears to underpin Liebow’s perspective – “"Now we have a set of basic standards that allow for the discovery, description, communication, cataloging and securing of messages that allow applications to talk to one another …” and “it's something I would call SOI, or service-oriented integration. It's exposing some applications to being connected …” – that SOA is primarily concerned with exposing application functionality and information as services and, more specifically, an open standards-based approach to EAI. This is certainly an important aspect of a service-oriented approach to IT but it is not sufficient.
Whilst it is true to say that ‘old’ SOA was primarily concerned with application development and integration, things have moved on. IT organisations are now under significantly greater pressure to justify business investment in IT (and even the existence of the IT organisation itself). To do so, they must explain the business value of the capabilities they offer in a consistent way. Presenting those capabilities as services within a structured management framework is a well-proven approach. But those capabilities are about much more than application functionality and information – there’s the infrastructure services they depend on and the lifecycle services that are responsible for the design, development, operation and change of the both the application and infrastructure services. And there are the contracts which govern the interactions between providers and consumers. Not just the functional aspects of the interaction but also the quality-of-service and commercial aspects.
So Liebow’s comments, whilst valid, only address a subset of what’s new about SOA. SOA today is an approach which demands a more holistic consideration of the different types of IT service and their associated contracts.
