RE: [soa-rm] Definition(s) of "service"

[Ken Laskey <klaskey@mitre.org>]

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

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   /   Ken 
Laskey                                                                \
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