W3C home > Mailing lists > Public > public-ws-policy@w3.org > August 2006

RE: NEW ISSUE: "Policy Alternatives" and "Policy" need proper def inition

From: Prasad Yendluri <prasad.yendluri@webmethods.com>
Date: Mon, 31 Jul 2006 17:31:44 -0700
Message-ID: <A3E375FA108EF94496269A5A96AFCAC1064AE986@mailwest-e0b>
To: Daniel Roth <Daniel.Roth@microsoft.com>, Prasad Yendluri <prasad.yendluri@webmethods.com>, public-ws-policy@w3.org
Dan,

 

Policy is defined to be a "collection of policy alternatives" only. Since an
assertion in policy alternative can embed another policy (as defined below),
a policy can end-up with policy alternatives in the policy embedded (in an
assertion of an alternative).

 

   <Assertion ...>

  ...

  ( <wsp:Policy ...> ... </wsp:Policy> )?

  ...

</Assertion>

 

There is generally no ambiguity until we run into further specifications
that state things like "Two policies
<http://www.w3.org/2002/ws/policy/6/07/27/ws-policy-framework.html#policy#po
licy>  are compatible if an alternative in one is compatible with an
alternative in the other."

 

Suppose you have the following two Policy specifications:

 

            Example Policy 1:

 

 <wsp:All> 

   <wsp:ExactlyOne>      <!-Alternative A -->

          <!-- assertion 6 --> 

          <!-- assertion 7 -->

   </wsp:ExactlyOne>

   <!-- assertion 8 -->  <!-Alternative B -->

</wsp:All>

 

               Example Policy 2:

 

<wsp:All>

  <wsp:ExactlyOne>  <!-Alternative 1 Top level -->

    <!-- assertion 1 -->

    <!-- assertion 2 -->

  </wsp:ExactlyOne>

  <wsp:ExactlyOne>  <!-Alternative 2 Top level -->

    <!-- assertion 4 -->

    <wsp:All> 

        <!-- assertion 5 -->  <!-Alternative 3 Nested -->

        <wsp:ExactlyOne>      <!-Alternative 4 Nested -->

          <!-- assertion 6 --> 

          <!-- assertion 7 -->

       </wsp:ExactlyOne>

    </wsp:All>

  </wsp:ExactlyOne>

</wsp:All>

 

 

Turns out <!-Alternative A --> in Example Policy 1 is compatible with (same
definition as) the "nested" policy alternative marked 

<!-Alternative 4 Nested --> in Example Policy 2.

 

Then using the definition, "Two policies
<http://www.w3.org/2002/ws/policy/6/07/27/ws-policy-framework.html#policy#po
licy>  are compatible if an alternative in one is compatible with an
alternative in the other.", one can conclude that Example Policy 1 and
Example Policy 2 are compatible, without further qualification of
"alternative in a policy". In reality, the policies are not compatible of
course even though, based purely on the current definition of policy (and
other related entities), one can arrive at that conclusion.

 

Hope that clarifies the issue.

 

Regards,

Prasad

 

  _____  

From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Daniel Roth
Sent: Monday, July 31, 2006 4:24 PM
To: Prasad Yendluri; public-ws-policy@w3.org
Subject: RE: NEW ISSUE: "Policy Alternatives" and "Policy" need proper
definit ion

 

I'm having difficulty understanding this issue.  Some examples that
demonstrate how the current definitions are ambiguous would be helpful.

 

Thanks.

 

Daniel Roth

 

  _____  

From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Prasad Yendluri
Sent: Wednesday, July 26, 2006 4:15 PM
To: public-ws-policy@w3.org
Subject: NEW ISSUE: "Policy Alternatives" and "Policy" need proper definit
ion

 

Title: "Policy Alternatives" and "Policy" need proper definition

 

Description: Section 2.3 terminology defines a "policy" to be, "a collection
of policy alternatives
<http://dev.w3.org/cvsweb/~checkout~/2006/ws/policy/ws-policy-framework.html
?content-type=text/html;%20charset=utf-8#policy_alternative#policy_alternati
ve> "

No further constraints on how these alternatives are grouped, i.e. on the
origin of alternatives in the collection.

 

Similarly section 3.2 (Policy) defines a "policy" to be: "a policy
<http://dev.w3.org/cvsweb/~checkout~/2006/ws/policy/ws-policy-framework.html
?content-type=text/html;%20charset=utf-8#policy#policy>  is a potentially
empty collection of policy alternatives
<http://dev.w3.org/cvsweb/~checkout~/2006/ws/policy/ws-policy-framework.html
?content-type=text/html;%20charset=utf-8#policy_alternative#policy_alternati
ve> ."

 

This "collection" does not account for level of nesting of a specific policy
alternative. 

 

Section 2.3 terminology defines a "Policy Alternative" to be "a collection
of policy assertions
<http://dev.w3.org/cvsweb/~checkout~/2006/ws/policy/ws-policy-framework.html
?content-type=text/html;%20charset=utf-8#policy_assertion#policy_assertion>
" only. 

No further restriction on how these assertions are grouped (or) the origin
of the assertions in the collection.

 

 

Similarly section 3.2 (Policy Alternative) defines a policy alternative to
be: 

"A policy alternative
<http://dev.w3.org/cvsweb/~checkout~/2006/ws/policy/ws-policy-framework.html
?content-type=text/html;%20charset=utf-8#policy_alternative#policy_alternati
ve>  is a logical construct which represents a potentially empty collection
of policy assertions
<http://dev.w3.org/cvsweb/~checkout~/2006/ws/policy/ws-policy-framework.html
?content-type=text/html;%20charset=utf-8#policy_assertion#policy_assertion>
. An alternative with zero assertions indicates no behaviors."

 

This "collection" again does not account for level of nesting of a policy
assertion included.

 

Justification:

There is scope for interpretation that needs to be eliminated. "policy
assertion" and "policy" definitions need to account for level of nesting of
the collection they define. 

 

Target: WS-Policy 1.5 - Framework

 

Proposal - Tighten up the definitions of "policy" and "policy assertion".
Sorry I have not come up suggestion for a specific replacement text at this
point.

Hope to follow-up later.

 

 

Regards,

Prasad Yendluri

 
Received on Tuesday, 1 August 2006 00:32:57 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 19:33:13 UTC