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Subject: Re: [soa-rm] Definition(s) of "service"
I also prefer Ron's version. -matt Chiusano Joseph wrote: >>-----Original Message----- >>From: Schuldt, Ron L [mailto:ron.l.schuldt@lmco.com] >>Sent: Wednesday, July 27, 2005 5:34 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" >> >> > >I like that much better. > >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: 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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