Re: [soa-rm-ra] reading WS-Policy: first observation

[Francis McCabe <frankmccabe@mac.com>]

I think that the WS-Policy framework should be interpreted as a  
simplification of what we had in mind.

In particular, the three aspects:
>
> Note per WS-Policy Framework,
> - a "policy" is a collections of policy alternatives, where
> - a "policy alternative" is a collection of policy assertions, where
> - a "policy assertion" represents a requirement, capability, or  
> other property of a behavior.

represent a simplified policy language. This has both benefits and  
demerits. It is simple, and easily implemented and (more importantly)  
easy to reason with. On the other hand, you cannot express a policy  
constraint such as price less than $100, or cheapest price.

Personally, I think that WS-Policy represents a too-strong commitment  
to a particular technology.

>
> Note also,
> - a "policy attachment" is a mechanism for associating policy with  
> one or more policy scopes. where
> - a "policy scope" is a collection of policy subjects to which a  
> policy applies, where
> - a "policy subject" is an entity with which a policy can be  
> associated.

I think that these concepts could be better explored. I think that we  
would also want to add "policy owner" at the very least. Also, the  
policy subject bears a strong resemblance to the (in)famous WS  
resource (the resource that a WS is 'about'). It works for many cases  
but not all: e.g., managers should earn more than their members. All  
the services in group X should be started simultaneously.

Frank


>
> Obviously, any part of a service or service description can be a  
> policy subject.  The question, as noted in current RA text, is how  
> do you discover something and decide to use it if critical policies  
> can be embedded anywhere.
>
> I read on :-)
>
> Ken
>
> P.S. I realize the RA does not directly "use" WS-Policy but if we  
> decide not to be consistent, then we need to make our alternatives  
> and our rationale very clear.
>
> ---------------------------------------------------------------------- 
> --------------------
> Ken Laskey
> MITRE Corporation, M/S H305     phone:  703-983-7934
> 7515 Colshire Drive                        fax:        703-983-1379
> McLean VA 22102-7508
>