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Subject: RE: [soa-rm] Definition(s) of "service"
I'd still like to emphasize service as the access to capabilities for which there are extra-service motivations for their existence and requirements for use of the capabilities that must be navigated by the service. Thus, "A service is a mechanism to enable access to a set of capabilities, where the access is provided using a prescribed interface and is exercised consistent with constraints and policies as specified by the service description." Ken At 11:15 PM 8/3/2005, joe@pantella.net wrote: >Just trying to sort through this; some common themes that seem to be >acceptable: > >A service provides capabilities. >A service is accessible. (If this is true, then service cannot be a >verb.) A service has an interface. (If this is true, then a service >has a boundary.) >A service interface is prescribed. (Then a service and its interface >are distinct, and the interface has associated rules. I'm not sure >this is true, the interface may describe the rules, but Im not sure >it has rules. In fact, I'm inclined to suggest that the interface >defines the rules for accessing the service. Which would lead me to >suggest that the service interface is more than a specification of >the data model, but also of the policies associated with the service.) >A service is a set of behaviors. (Not sure I'm on board with this, >something about behaviors doesn't sit well.) > >Given this, perhaps something like: > >"A service is a bounded set of capabilities that are accessible >through a prescribed interface." > > >-- JJP > >P.S. I think this definition might just be flexible enough to >navigate the service offer/contract discussion also. > > >-----Original Message----- >From: Schuldt, Ron L [mailto:ron.l.schuldt@lmco.com] >Sent: Thursday, July 28, 2005 12:32 PM >To: Frank McCabe; SOA-RM >Subject: RE: [soa-rm] Definition(s) of "service" > > >Frank, > >While I believe that the previously proposed definition is >sufficient, I offer the following as a compromise. Hopefully, the >notion of "capabilities" addresses your issue of needing to get things done. > >"A service is a set of behaviors to provide capabilities accessible >via a prescribed interface." > >Ron > > >-----Original Message----- >From: Frank McCabe [mailto:frank.mccabe@us.fujitsu.com] >Sent: Thursday, July 28, 2005 10:10 AM >To: SOA-RM >Subject: Re: [soa-rm] Definition(s) of "service" > > >I hesitate to spoil this party ... but I'm going to :) > >1. There is a distinction between action and result. (Just ask any >roboticist) Behaviour sounds a child misbehaving with no discernible >effect. Computer Scientists have a tendency to focus on the purely >technical aspects of their work: bytes shuffling around at random >within hopefully enormous memories. >2. Also, we have to bear in mind that nobody invests millions of $s >(or even 100's of them) in systems that contemplate their navels or >have no business payoff. I think that we have to directly address the >reason that services are deployed. >3. One of the movitating best practice aspects of SOAs is that >clarity and 'separation' between the providers of services and the >consumers of services leads to more scalable and robust architectures. > >All of the above is fuzzy language; but, at the same time, "A >service is a set of behaviors accessible via a prescribed interface." >sounds a lot like bureauspeak. > >I believe that there is strong consensus on the following >characteristics: >a. The concept of service is 'at the boundary' between service >providers and consumers. >b. The service is 'there' to get things done; but doesn't itself >denote the engine that performs the tasks. >c. There is a reason for using a service. >d. There is a lot of extra metalogical information about services >that make it possible for third parties to develop partners for >services. > >I, for one, would prefer a strongly anglo-saxon phrasing of the >definition of service that speaks to these points. > >Frank >ti -- --------------------------------------------------------------------------------- / Ken Laskey \ | MITRE Corporation, M/S H305 phone: 703-983-7934 | | 7515 Colshire Drive fax: 703-983-1379 | \ McLean VA 22102-7508 / ----------------------------------------------------------------------------------
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