Re: [soa-rm-ra] OMG Pro Use of Agents [Resources & Capabilities]



Ken and Michael,

 

Straight from the W3C WSA...

 

"A service is an abstract resource that 
represents a capability of performing tasks that represents a coherent 
functionality from the point of view of provider entities [p.35] and requester 
entities [p.36] . To be used, a service must be realized by a concrete provider 
agent [p.34] ."

 

Does this 
help get at your points?  (Incidentally, the WSA adopts the RFC 2396 definition of a resource, 
which is anything that can have an identifier.)

 

I think there 
is another very important observation that warrants pointing out as part of this 
discussion:

 

The way I see 
it, a capability is more than just being able to perform certain 
"tasks that represent coherent functionality."  A capability also 
includes certain quality attributes.  In other words, it's not just 
WHAT functions the resource (or service) performs but also HOW WELL it can 
perform those functions.  Could be a metric of reliability (99.7% 
availability), performance (10 ms response time), or some other quality 
attribute.  Usually, we don't know this a priori of invoking a service 
except for what is provided in the Service Description artifact.  
Certainly, the Service Description artifact should include or at 
least point to another artifact that describes the service's overall 
capabilities (functionality and quality attributes) to help the prospective 
consumer determine if it is a service worthy of meeting the consumer's 
needs.

 

Cheers...

 

 - Jeff