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Subject: Re: [soa-rm] Definition(s) of "service"
I'm on board with this as well. Wow. What a productive thread! -matt John Harby wrote: >"A service is a set of behaviors accessible via a prescribed interface." > >I like this one also. > >On 7/28/05, Oleg Mikulinsky <oleg.mikulinsky@weblayers.com> wrote: > > >>+1. >> >>I would prefer to remove the notion of boundary in favor of the >>interface. As the definition of the interface implies boundary in my >>mind. >> >>Oleg. >> >>-----Original Message----- >>From: Schuldt, Ron L [mailto:ron.l.schuldt@lmco.com] >>Sent: Thursday, July 28, 2005 9:33 AM >>To: Chiusano Joseph; soa-rm@lists.oasis-open.org >>Subject: RE: [soa-rm] Definition(s) of "service" >> >>I like that as well. >> >>Ron >> >> >>-----Original Message----- >>From: Chiusano Joseph [mailto:chiusano_joseph@bah.com] >>Sent: Thursday, July 28, 2005 7:30 AM >>To: soa-rm@lists.oasis-open.org >>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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