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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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