David Chappell (http://www.davidchappell.com/HTML_email/Opinari_No16_8_06.html) argues that SOA may not foster the service reuse that everyone has been hoping for. I think his analysis is correct, but I think with business services we at least have a reasonable hope of achieving reuse. Here we are least dealing with the way things actually happen in the world as opposed to programmer abstractions such as objects or components. That combined with the looser coupling of services gives me some hope.

The reason why frameworks like .NET are successful is they reflect years and years of experience with programming problems. Many examples of reuse (such as file systems and compilers) are so embedded in our experience that we no longer see them for what they are.

Reuse may fail here as well for all the reasons mentioned in David Chappell's analysis. At least now I feel we are on the right track.

The Reference Model for Service Oriented Architecture defines a vocabulary for building service-oriented systems. Put together by a technical committee operating under the auspices of the OASIS standards organization, it is the result of individuals and organizations representing vendors, users, governments, consulting organizations, and academic institutions.

The Reference Model (RM) sees SOA as a means for organizing and using distributed capabilities that may be under the control of different ownership domains. The RM is not an architecture. It does not attempt to make any architecture normative. It does not try to make any standard or set of standards normative.

It does provide a common set of semantics that can be used across different implementations. This does sound rather fancy. Nonetheless, just like Moliere's bourgeois gentlemen that found out he was speaking prose all his life, many industries have been using reference models all along. They just never had to define them explicitly.

An architect for a residential dwelling knows that if they use the term door or window, the builder will understand what is meant. There are widely varied implementations of doors and windows depending, for example, if you are building a space station or an igloo. Nonetheless, everyone knows what the terms mean. Many of these terms are codified in building codes, and by standards bodies, and have evolved over the years. The software architecture community moves too quickly for such evolution; this is where standards organizations can help.

Software architectures, for sure, can have views and viewpoints, but the terms in which they are discussed have to be understood.

The core concepts that the RM discusses are service, visibility, execution context,  service description, real world effect,  interaction, and contract and policy.

I will discuss these core concepts over the next few posts.

None of this work is going on in isolation, or is it intended to denigrate other work such as the WS* specifications, or organizations such as the ISO, IEEE, IETF, the Ontolog Forum or other groups. The reference model just supplies standard definitions so that it becomes easier for each group to communicate with the others.