What is SOA (Service Oriented Architecture)?

Question

Call me a troll if you want, but I\'m serious: how exactly is the new SOA trend any different than the client-service architecture that I was building 15 years ago?

Answer 1

For me, a Service Oriented Architecture comes about when an Enterprise wishes to integrate a selection of disparate applications which concern a common domain into a set of interoperable services which operate against a single data source.

In the case of a new startup company with an idea for an item of software/suite of softwares, I can't see how a company can kick off with a Service Oriented Architecture from the off. At first, each solution (which may well evolve into a service such that it may become interoperable) should seek to solve its problem space in isolation.

Perhaps it will be in the roadmap for an enterprise capability or suite for each solution to become an interoperable service as the solutions are completed and enter service. For this, perhaps the development teams will undertake a modular/component oriented approach to building the soluton (eventual service), so as to make it easier to include the solution as a service in a Service Oriented Architecture.

In the case where existing islands of software are to become interoperable services in a Service Oriented Architecture, the approach allows for the software items - which may be distributed and may be written in different languages - to communicate via an exposed API and/or common protocol (for example a flavor of Web Service) and generic data format (for example XML).

SOA is an approach or idea. It is not a framework or a tool. When WDSLs and EJBs get name-dropped, this is often forgotten... as is that the idea of SOA is not new at all.