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Why the SOA Reference Architecture ?

The OASIS SOA Reference Architecture is one of the best introductions to SOA, providing a complete, consistent and largely non-technical set of concepts and definitions for SOA technology. It may be the easiest way to understand SOA without digging through volumes of arcane technical standards and XML specifications.

But the reader should be aware that the OASIS Reference Architecture does not provide detailed descriptions of the components required for implementing an SOA application. This is true of reference architectures in general.

The Reference Architecture document states:

A reference model consists of a minimal set of unifying concepts, axioms and relationships within a particular problem domain, and is independent of specific standards, technologies, implementations, or other concrete details.

What the architecture lacks is the "standards, technologies, implementations, or other concrete details" necessary to make it a working framework for SOA-enable applications. However, it is also important to realize that those standards and details are not lacking in the standards firmament ( firmament is not too strong a word ).

Among the 'details' missing in the Reference Architecture are XML and several dozen XM-based data interchange and message exchange standards. For example, the core standards for service discovery and interface are Universal Description Discovery and Integration (UDDI) and Web Services Description Language (WSDL). For the technically-inclined, the W3C Web Services Architecture provides a far more detailed description of specific design features and implementation structures missing in the OASIS architecture. Though the W3C WSA specification mentions SOA only in passing, the technical environment they describe is nearly identical to many of the mainstream SOA methodologies.

It is important to note that the W3C WSA has been fairly static for the last 3 years old, basically in a state of suspended animation with some flurries of activity from time to time. On the other hand, the more human-oriented OASIS architecture is only a few months old, in direct defiance of the usual expectation that new projects and new ideas will progress naturally from formulating high-level requirements to the hacking-out of nitty-gritty details later in the implementation phases of development.

Clearly, this suggests that something was missing from the W3C technical achitecture and is being addressed in the less technically-inclined OASIS architecture. This might provide the key factor in moving SOA from a concept to a reality, that is, answering the question why do SOA, rather than simply describing how to do it and hoping that the 'inherent superiority' of the technology can carry the day on its own.

Also see: Link - Semantic Web Services Architecture