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

["Schuldt, Ron L" <ron.l.schuldt@lmco.com>]

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
>>
>>
>>>
>>
>