Re: [soa-rm-ra] Service & Capability

[Rex Brooks <rexb@starbourne.com>]

My $.02:

Capabilities are often associated with Actions in the sense that 
Actions represent one set of mechanisms, as we define it, by which 
real world effects are realized. In fact, we define Action in a 
couple of modes, Joint Action by which listenerss and speakers act 
more or less in concert is discussed in 3.1.2 Communication as Joint 
Action [sic] Model and shown in Figure 7 on page 27 of the draft 
Frank distributed yesterday night.

(Thanks Frank! but wasn't "Model" supposed to disappear there and 
appear in 3.1 and 3.3?).

The next section, 3.1.3 discusses how Communication is used in 
Service Action, the other major form of Action. Action as a atomic 
concept is defined as Ken said. We've been going round and round to 
get consistency on this. I think we're getting closer.

However, we also discuss how Capability at a slightly higher level of 
abstraction in 3.3.1 Needs and Capabilities where Figure 15 shows how 
Capability achieves a Real World Effect. Since that occurs just 
before Resources are discussed, I can see where it might seem that we 
should delineate the slight difference in the way Real World Effects 
are seen to be achieved at the higher level of abstraction, where I 
would say that Action is subsumed in Figure 15 as one way in which 
RWE is realized. Just above that, in 3.3 Figure 14 Social Action (as 
distinct different from Joint [Communication] Action and Service 
Action), is also shown as resulting in an RWE. This is likely to be 
discussed, but I think its appropriate.

Cheers,
Rex

At 6:34 PM -0500 1/29/09, Ken Laskey wrote:
>Jim,
>
>First, what is meant by Action has been a continuing source of 
>debate, and I'm not sure it's been resolved with respect to section 
>3.
>
>With that as a caveat, my interpretation is
>1. A capability is something that can be brought to bear to address 
>some set of needs.
>2. The results of using a capabilities are a set of real world 
>effects that represent an effect on (and ideally a satisfaction of) 
>the needs.
>3. SOA services access capabilities and thus by exercising those 
>capabilities, results in certain real world effects.  Note the real 
>world effects of the service may not merely match the real world 
>effects of the service because more things may be going on than 
>accessing a single capability.
>4. (This gets touchier.) An action is the application of intent (by 
>a consumer) that somehow has the service do its stuff and producing 
>real world effects.  But when a service receives a message, a Web 
>Services implementation would kick off a WSDL operation, and there 
>is a certain extent to which Action as connected to description and 
>interaction maps to that WSDL operation.  I have no doubt others 
>will further muddy this point.
>
>Ken
>
>On Jan 29, 2009, at 5:40 PM, James Odell wrote:
>
>>Hi all,
>>
>>OK, just one last question for today.
>>
>>In 4.3.2, Services perform Actions that cause Real World Effects.
>>In 3.3.1, Services have Capabilities that achieve Real World Effects.
>>
>>It would seem that there Actions and Capabilities have some close 
>>conceptual tie, here.  Are Capabilities defined in terms of the 
>>Action(s) they provide?  Or, ...?
>>
>>
>>-Jim
>>
>
>-----------------------------------------------------------------------------
>Ken Laskey
>MITRE Corporation, M/S H305      phone: 703-983-7934
>7515 Colshire Drive                         fax:       703-983-1379
>McLean VA 22102-7508


-- 
Rex Brooks
President, CEO
Starbourne Communications Design
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Berkeley, CA 94702
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