Today I read an article from ZapThink -- "Divorcing SOA from Web Services", where the author is basically saying that many people in the industry incorrectly equate SOA with Web Services. I came across similar situations. Every time there is a talk about SOA management it is automatically being associated with Web Service management. I guess most organizations are implementing SOA using Web Services. Come to think about it, if an organization is trying implement SOA, what technologies would they use? Is Web Services the only viable way of creating service orientation? Well surely CORBA is a candidate, but is anyone actually doing this? Big part of SOA is not just service orientation but also service interoperability.
Did Web Services become a defacto standard for developing service oriented composite applications? Clearly Web Services is not enough to achieve true SOA implementation, that is where ESBs (Enterprise Service Bus) come to the picture.
The article also introduces the term SOI (Service Oriented Infrastructure) which is basically the building blocks of the SOA paradigm such as message bus, ESB etc. So organizations must effectively translate SOA into specific SOI as well as come up with best practices to support it. So the question is when do you truly achieve service orientation? I guess that would be organization specific. If SOA is about business services -- SOA implementation would mean to compose/create reusable business services that can be integrated and reused on-demand. The granularity of the service interfaces and would be organization and business centric.
So if Web Services follow "bind-publish-use" paradigm, SOA would be "bind-publish-compose-use" where each composition of services is in itself a business service can be used as independent service.
That makes sense.