Andrew, I actually think you've hit a pretty good distinction and definition.
Steve 2009/12/17 Andrew Herbst <[email protected]> > > > Greetings: > > Another question from an SOA neophyte. Thanks for responding to my > earlier questions. > > I suspect this question will be easy. I am not certain I understand the > distinction between a “service description” and a “service contract”, in > specific respect to the *mechanics* of interaction (I am aware that > service descriptions provide other information as well). At one level, I > think there is an obvious distinction – a description is a thing that > characterizes one service, while the contract is an entity that governs the > interaction of two (or more) services. From various sources descriptions, > I read about how a contract is constituted by description documents. I > find such statements a little confusing. > > > Clearly these two notions are tightly related. In the OASIS RAF, I read > this: “Recall the fundamental definition of service is a mechanism to > access an underlying capability; the service description describes this > mechanism and its use. It lays the groundwork for what *can* occur, > whereas service interaction defines the specifics through which *occurrences > are realized*.” And, of course, the contract is related to service > interaction. > > > I will venture the following answer to my own question. Can you please > comment on whether I am close to capturing the “description vs contract” > distinction, at least at the conceptual level, and in specific respect to > matters of mechanisms of interaction: “*A service description tells > potential consumers about all possible mechanisms for interacting with the > service. When a service consumer enters into a contract with a service > provider, both parties enter into an agreement that a specific set of > mechanisms will, in fact, be used*” > > So, roughly speaking, a service description is like me announcing to the > world: “I can interact in French *or* in English”, whereas, a service > contract is like me agreeing to speak French with a specific other person in > the context of some very specific interaction. > > I realize this is a very basic question, and it may well not really be the > aim of this group to deal with such basic things. I will therefore take > no offence if no one addresses this. > > Thanks, > > Andrew Herbst > > > >
