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

["Jeffrey A. Estefan" <jeffrey.a.estefan@jpl.nasa.gov>]



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