During a recent trip to a company technical summit a discussion came about related to how SOA is just Web Services. As a SOA Trainer, Architect and Implementer I live and breath it every day. Most peoples perspectives probably fall in this category and currently most of the SOA implementations that I have worked with have used Web Services. The key is that Web Services is just an implementation technology not a SOA.
Books from Thomas Erl, Intel Press and others have identified that SOA is a design paradigm that focuses on a series of principles that tie back into key business goals and benefits. Examples of these are presented at SOA Systems but include:
- Cooperative Development between Business Analysts and Technical Architects
- Vendor/Technology Choice
- Reduced IT Effort
- Business Agility
Now a SOA could be constructed using CORBA, Java, SCA/SDO, Web Services, REST etc. The implementation mechanism that one chooses should support interoperability, federation etc. Currently XML Based technologies provide the best interoperability both in communication/exchange but in vendor support, standards, tooling but this may change over time and probably will.
So if a person asks me what SOA is, I simple identify it as a design paradigm for developing and evolutionary distributed architecture. It has its basis in OO, AOP, EAI, BPM and other styles. It is like the Bruce Lee of architectures having evolved from various fighting styles.