Yes, I think a unit of composition is ok. In the old days (!) I would have called it an application subsystem (order entry, inventory management, customer management, etc.)
--- "Spork, Murray" <[EMAIL PROTECTED]> wrote: > > -----Original Message----- > > From: > [email protected] > > > [mailto:[EMAIL PROTECTED] > On > > Behalf Of Eric Newcomer > > Sent: Saturday, 21 January 2006 6:08 PM > > > Well, the main point is that a service is not an > > object. A service is a verb, not a noun. You > might > > have a collection of verbs in a service, which > might > > be part of the confusion. The one quibble I have > with > > the definition we use in our course material is > that I > > usually prefer to define something in the > singular. > > We have defined a service as a group of functions. > I > > would more usually call one of those functions a > > service, and the group a group of services. So I > > agree (assuming that's your point) that this > > definition is a big ambiguous. > > The question would seem to be: what unmbiguous > criteria can we apply to > say that a collection of service operations (in WSDL > terminolgy) belong > together in one service interface? > > A simple answer we can borrow from > component-orientation is that a > service should represent a "unit of composition" - > i.e. a service is > replaceable with another one that exposes the same > semantic > functionality (modulo syntactic and behavioral > differences). Taking your > banking example, it's unlikely that I would be able > to replace my > "withdraw funds" operation without at the same time > replacing "transfer > funds". That's why these 2 operations probably > belong to the same > service interface. (btw I like your term "service > function" much better > than the WSDL term "operation"). > > Murray > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/service-orientated-architecture/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
