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Subject: RE: [soa-rm] Definition(s) of "service"
> -----Original Message----- > From: Schuldt, Ron L [mailto:ron.l.schuldt@lmco.com] > Sent: Thursday, July 28, 2005 9:27 AM > To: Thomas Erl; soa-rm@lists.oasis-open.org > Subject: RE: [soa-rm] Definition(s) of "service" > > Believe it or not I thought about this at about 2 AM this > morning. I agree with Thomas that a service is a set of > behaviors. To fully define a service in the context of a > reference model for SOA, I suggest the following (a slight > modification of Thomas' words) > > A service is a set of behaviors within a given action > boundary accessible via a prescribed interface. I like that. I also wonder if the reference to a prescribed interface might imply the notion of a boundary (or action boundary) - in which case we can remove the reference to action boundary. The new version would be: "A service is a set of behaviors accessible via a prescribed interface." Joe Joseph Chiusano Booz Allen Hamilton O: 703-902-6923 C: 202-251-0731 Visit us online@ http://www.boozallen.com > Ron > > > -----Original Message----- > From: Thomas Erl [mailto:thomas.erl@soasystems.com] > Sent: Wednesday, July 27, 2005 8:23 PM > To: soa-rm@lists.oasis-open.org > Subject: Re: [soa-rm] Definition(s) of "service" > > > I would view the interface and the action boundary as > elements that partially comprise a service. I would therefore > not state that a service > *is* a prescribed interface or *is* an action boundary (to a > set of behaviors). Would a service not represent a set of > behaviors within a given action boundary accessible via a > prescribed interface? > > Thomas > > ----- Original Message ----- > From: "Behera, Prasanta" <pbehera@visa.com> > To: <soa-rm@lists.oasis-open.org> > Sent: Wednesday, July 27, 2005 5:05 PM > Subject: RE: [soa-rm] Definition(s) of "service" > > > > Ron: "A service is a prescribed interface to a set of behaviors" > Frank: "A service is an abstract action boundary to a set of > behaviours" > > The difference between the two seems to be "prescribed interface" Vs. > "abstract action boundary" (Skipping the "behaviors" and "behaviours" > debate). > > I would lean more towards Ron's suggestion. > Thanks, > /Prasanta > > > -----Original Message----- > From: Schuldt, Ron L [mailto:ron.l.schuldt@lmco.com] > Sent: Wednesday, July 27, 2005 2:34 PM > To: Duane Nickull; Francis McCabe > Cc: soa-rm@lists.oasis-open.org > Subject: RE: [soa-rm] Definition(s) of "service" > > I briefly suggested something similar to this during the F2F > > I'll toss out a slight modification based on this thread to the TC for > their reaction. > > "A service is a prescribed interface to a set of behaviors" > > Ron > > > -----Original Message----- > From: Duane Nickull [mailto:dnickull@adobe.com] > Sent: Wednesday, July 27, 2005 3:24 PM > To: Francis McCabe > Cc: soa-rm@lists.oasis-open.org > Subject: Re: [soa-rm] Definition(s) of "service" > > > Frank: > > I wasn't happy with "observable" either. Perhaps firing up the ole' > thesaurus to find out an "observable / effective / RWE" > synonym would be > > a good idea or just being vague and not using the word. > > The wording of this is becoming somewhat scatalogical in nature due to > the amount of FUD in the industry ;-) > > Duane > > > > > Francis McCabe wrote: > > > I rather like this definition. I agree completely that > service should > > > not mention the delivery mechanism. Some additional comments: > > > > Firstly, I would shorten it to: > > > > "A service is an abstract action boundary to a set of behaviours" > > > > Rationale: The service is distinct from the results of the service. > > > > Secondly, building on the notion that behaviour is different to > > effect, I would go on to: > > > > "A service is an abstract action boundary to a set of effective > > behaviours" > > > > Not sure about the word effective, as it may be ambiguous > in ordinary > > > English. > > > > Frank > > > > > > > > > > > > > > On Jul 27, 2005, at 2:04 PM, Duane Nickull wrote: > > > >> Perhaps combining all of these is closer to the answer: > >> > >> Duane suggests: "A service is an abstract action boundary to a set > >> of behaviours or the observable result of some functionality." > >> > >> I would want to refrain from mentioning any actors such as > provider, > > >> consumer, participant in this definition since we may define those > >> later by referring to service (avoidance of circular > references). I > >> used the word "abstract" specific to our RM. In an RA, it may be a > >> more concrete action boundary (see Microsoft def. below). > >> > >> More definitions of services: > >> > >> W3C says: "A Web service <http://www.w3.org/TR/ws-arch/#service> is > >> an abstract notion that must be implemented by a concrete agent > >> <http://www.w3.org/TR/ws-arch/#agent>." (Thank you W3C. I am more > >> confused now. Next!) > >> > >> Microsoft says: "A software entity whose interactions with other > >> entities are via messages. Note that that > >> a service need not be connected to a network." (too concrete but > >> good for RA. I wonder why they felt compelled to point out that it > >> need not be connected to the network to be a service. This is in > >> alignment with our notion of "a service is a service, even if not > >> invoked" so I like that part.) > >> > >> CISCO says: "A group of related functions (or operations) that work > >> together to provide a functional capability." (interesting but does > >> really state what a service is, just what it represents). > >> > >> The US EPA says: "Breeding, the deposition of boar semen into the > >> female." (Hmmm - probably not useful - let's leave this one alone) > >> > >> DOI says: "A defined result from a defined action ie, do X and the > >> result will be Y. Services perform functions when invoked into > >> action." (paraphrased slightly. Too concrete but interesting) > >> > >> Apple says: " A service is an I/O Kit entity, based on a > subclass of > > >> IOService, that has been published with the registerService method > >> and provides certain capabilities to other I/O Kit objects. In the > >> I/O Kit's layered architecture, each layer is a client of > the layer > >> below it and a provider of services to the layer above > it. A service > > >> type is identified by a matching dictionary that describes > >> properties of the service. A nub or driver can provide services to > >> other I/O Kit objects." > >> > >> I liked part of the latter analogy about the layering - being a > >> slave to the entity above it while being a client of the entity > >> below it. This effectively addresses the concept of > service context. > > >> In one context, something is a service consumer while in > another it > >> is a service provider. The definition is far to specific to Apple > >> but is useful to expand thinking. > >> > >> To continue extrapolating from Ken's ramblings, > >> "Two things are needed to effectively use a capability under SOA: > >> - understanding the underlying capability; > >> - understanding the accessing service." > >> > >> I fundamentally think that all that is really required is an > >> understanding of the behavioural aspects of the service, the data > >> model the service uses, the other metadata and the policies of the > >> service. > >> > >> Duane > >> > >> > >>> > >> > > > > >
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