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Subject: RE: [soa-rm] Definition(s) of "service"
I think it can be looked either way (resource-centric or non-resource-centric - if these terms work), depending on one's purpose. A software developer may need a resource-centric view as they would be concerned about what is behind the service, while a SOA architect who is approaching the architecture of a service-oriented system (SOS) from top-down would probably need (at least initially) to think in terms of an a non-resource-centric view, and consider the notion of a service without regard to any resource behind it (i.e. thinking about the existence of a resource would be too detailed for their purpose). This is with the understanding that a SOA architect would eventually need to worry about the resource, or interface with someone else who does. For our purposes (software SOA), we probably need the resource-centric view. Joe Joseph Chiusano Booz Allen Hamilton O: 703-902-6923 C: 202-251-0731 Visit us online@ http://www.boozallen.com > -----Original Message----- > From: Ken Laskey [mailto:klaskey@mitre.org] > Sent: Thursday, August 04, 2005 12:35 PM > To: soa-rm@lists.oasis-open.org > Subject: RE: [soa-rm] Definition(s) of "service" > > This gets back to the previous discussion when we talked > about resources, i.e to what extent the service is the > mechanism to access (possibly coordinate) capability vs. when > is it considered the capability itself. > > I think any consideration of the service as the > capability/resource should be very limited. > > Ken > > At 11:07 AM 8/4/2005, Chiusano Joseph wrote: > > > -----Original Message----- > > > From: Ken Laskey [mailto:klaskey@mitre.org] > > > Sent: Thursday, August 04, 2005 11:04 AM > > > To: Chiusano Joseph; soa-rm@lists.oasis-open.org > > > Subject: RE: [soa-rm] Definition(s) of "service" > > > > > > Somehow saying service *provides* capabilities misses the SOA > > > motivation to provide an effective way to bring together > the parts I > > > need to solve a problem. Integration is often of disparate parts > > > that exist for their own purposes. Service can help > coordinate but > > > the challenge is to make use of the tools/resources/capabilities > > > that already exist, not to create new stovepipes. Saying the > > > service provides all this is a tempting simplification > but I fear it > > > will trivialize the concepts most in need of clarification. > > > >Agree - and I should clarify that I was merely saying that a service > >provides capabilities (in general). Combining a capability here, a > >capability there, here a capability, there a capability, > everywhere a > >capability (oops sorry - that's the EIEIO song), we have composite > >capabilities. > > > >Joe > > > >Joseph Chiusano > >Booz Allen Hamilton > >O: 703-902-6923 > >C: 202-251-0731 > >Visit us online@ http://www.boozallen.com > > > > > Ken > > > > > > At 10:35 AM 8/4/2005, Chiusano Joseph wrote: > > > > > -----Original Message----- > > > > > From: Ken Laskey [mailto:klaskey@mitre.org] > > > > > Sent: Thursday, August 04, 2005 10:18 AM > > > > > To: soa-rm@lists.oasis-open.org > > > > > 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, > > > > > > > >I would say that access control mechanisms enable such > > > access, and that > > > >the service *provides* the capabilities. Note: Use of > > > "access control" > > > >is too concrete for our RM - I stated it only to illustrate > > > the point. > > > > > > > >Joe > > > > > > > >Joseph Chiusano > > > >Booz Allen Hamilton > > > >O: 703-902-6923 > > > >C: 202-251-0731 > > > >Visit us online@ http://www.boozallen.com > > > > > > > > > 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 > > > > > / > > > > > > > > > > -------------------------------------------------------------- > > > > > -------------------- > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > -------------------------------------------------------------- > > > ------------------- > > > / Ken > > > Laskey > > > \ > > > | MITRE Corporation, M/S H305 phone: 703-983-7934 | > > > | 7515 Colshire Drive fax: > > > 703-983-1379 | > > > \ McLean VA 22102-7508 > > > / > > > > > > -------------------------------------------------------------- > > > -------------------- > > > > > > > > > > > > > > -- > > -------------------------------------------------------------- > ------------------- > / 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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