I suppose there is an ambiguity arising throught the phrase "expose the capabilities", as we don't have a definition of "expose". Perhaps we could find better words to express the intended meaning. I wondered about "make available the capabilities and data", but this might be confused with provisioning. (I notice that the OGSA definition of "virtualization" has dropped the phrase "make available"). How about: "A service that provides interfaces to the capabilities and data of one or more data resources within a service-oriented architecture." Dave.

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guru prasad wrote: The definition just tells me that Data Service just exposes the capabilities and/or data of data resource(s). But, it does not tell me if I can access this service to invoke those capabilities or the data of a data resource.

Donal Fellows replied: It's exposing the capabilities, not (necessarily) a description of them. A capability isn't exposed if it isn't (at least in principle) accessible.