RE: policy vocabulary, will not be applied, oh my!

+1

An alternative with one or more assertions indicates behaviors implied by those, and only those assertions. If a policy alternative does not specify a behavior then the alternative means the behavior is not applied.

Regards,

Asir S Vedamuthu
Microsoft Corporation


From: public-ws-policy-request@w3.org [mailto:public-ws-policy-request@w3.org] On Behalf Of Christopher B Ferris
Sent: Tuesday, May 08, 2007 5:01 AM
To: public-ws-policy@w3.org
Subject: Re: policy vocabulary, will not be applied, oh my!


All,

I've been thinking about this, and possible language that would make things clear to the reader that an alternative's set of
assertions implies that ONLY those behaviors implied by those assertions are applied in the context of an interchange
governed by that policy alternative.

Also, since there isn't an issue to go with this thread, and it may well end up with CR edits to the
spec, I opened an issue (4544) in Bugzilla:

        http://www.w3.org/Bugs/Public/show_bug.cgi?id=4544

The first paragraph in section 3.2 of the Framework currently reads:

[Definition: A policy alternative is a potentially empty collection of policy assertions<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_assertion>.] An alternative with zero assertions indicates no behaviors. An alternative with one or more assertions indicates behaviors implied by those, and only those assertions. [Definition: A policy vocabulary is the set of all policy assertion types<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_assertion_type> used in a policy.] [Definition: A policy alternative vocabulary is the set of all policy assertion types<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_assertion_type> within the policy alternative<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_alternative>.] When an assertion whose type is part of the policy's vocabulary is not included in a policy alternative, the policy alternative without the assertion type indicates that the assertion will not be applied in the context of the attached policy subject. See the example in Section 4.3.1 Optional Policy Assertions<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#Optional_Policy_Assertions>

I would propose the following change:

[Definition: A policy alternative is a potentially empty collection of policy assertions<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_assertion>.] An alternative with zero assertions indicates no behaviors. An alternative with one or more assertions indicates behaviors implied by those, and only those assertions. No other behaviors are to be applied for the alternative.

The rest of the edits in the original proposal [1] remain unchanged.

[1] http://lists.w3.org/Archives/Public/public-ws-policy/2007May/0003.html

Cheers,

Christopher Ferris
STSM, Software Group Standards Strategy
email: chrisfer@us.ibm.com
blog: http://www.ibm.com/developerworks/blogs/page/chrisferris
phone: +1 508 377 9295

public-ws-policy-request@w3.org wrote on 05/07/2007 09:07:16 AM:

>
> +1,
>
> (Thanks Chris, for providing an example. Makes it much clearer for
> understanding issue.)
>
> regards, Frederick
>
> Frederick Hirsch
> Nokia
>
>
> On May 2, 2007, at 5:19 AM, ext Sergey Beryozkin wrote:
>
> > Hi Chris
> >
> > Would it be possible to post an example which would show a
> > realistic scenario where it's obvious the fact that the input
> > policy vocabulary is not included in the effective policy's
> > vocabulary may cause the problems for a client ? I just find it
> > difficult to understand the reasoning when policies A&B are used in
> > examples :-)
> >
> > Also, I don't understand why the client can not use the effective
> > policy's vocabulary as the guidance on what assertions can be
> > applied. The fact that many more assertions might've been involved
> > in the intersection seems unimportant to me, the client can not
> > apply what the effective policy has now, that is whatever
> > assertions are in the selected alternative. I think this is what
> > Monica said in the other email (sorry if misinterpreted that email
> > reply).
> >
> > I hope the practical example will help to understand the problem
> > better
> >
> > Thanks, Sergey
> > ----- Original Message -----
> > From: Christopher B Ferris
> > To: public-ws-policy@w3.org
> > Sent: Tuesday, May 01, 2007 9:22 PM
> > Subject: policy vocabulary, will not be applied, oh my!
> >
> >
> > There are some related issues/questions/concerns that have been
> > expressed by members
> > of the WG with regards the framework specification as it relates to
> > the "will not be applied" principle
> > and the definions for "policy vocabulary", etc. Below, I have
> > enumerated these issues
> > and suggest a path forward to address those concerns.
> >
> > 1. The definition of "policy vocabulary" is incompatible with
> > intersected policy as regards to
> > the "will not be applied" principle because post intersection, the
> > resultant policy expression
> > does not carry the policy vocabulary of the input policy
> > expressions. Hence, if a provider
> > had two alternatives, one with Foo and one without Foo, and the
> > result of intersection determined
> > that the alternative without Foo was compatible with a client's
> > policy, then the resultant
> > policy expression would not have in its vocabulary (as computed
> > using the algorithim
> > currently specified) Foo and hence it would not be clear whether
> > Foo carries with it
> > the "will not be applied" semantic.
> >
> > Action-283 - http://lists.w3.org/Archives/Public/public-ws-policy/
> > 2007Apr/0103.html
> > Action-284 - http://lists.w3.org/Archives/Public/public-ws-policy/
> > 2007Apr/0106.html
> > Ashok email - http://lists.w3.org/Archives/Public/public-ws-policy/
> > 2007Apr/0065.html
> >
> > 2. There is a degree of confusion regarding the "will not be
> > applied" semantic as it applies to nested policy.
> > This is related to the interpretation of "policy vocabulary" that
> > many held prior to the clarification provided by
> > Microsoft
> >
> > Asir's email on nested policy vocabulary - http://lists.w3.org/
> > Archives/Public/public-ws-policy/2007Apr/0017.html
> >
> > 3. As a result, a number of email threads have sprung up that
> > question the merits of the "will not be applied"
> > semantic.
> >
> > Ashok - http://lists.w3.org/Archives/Public/public-ws-policy/
> > 2007Apr/0065.html
> > Dale - http://lists.w3.org/Archives/Public/public-ws-policy/2007Apr/
> > 0075.html
> > Ashok - http://lists.w3.org/Archives/Public/public-ws-policy/
> > 2007Apr/0101.html
> > Dale - http://lists.w3.org/Archives/Public/public-ws-policy/2007Apr/
> > 0108.html
> >
> > It may be that the most prudent course forward would be to drop the
> > "will not be applied" semantic as relates
> > policy vocabulary. As a result, there is little need of a normative
> > definion for policy vocabulary or policy alternative
> > vocabulary, as these definitions only served to allow one to
> > determine whether the behavior implied by a
> > given assertion carried the "will not be applied" semantic.
> >
> > Instead, we could simply state that the behavior implied by an
> > assertion that is absent from a given alternative
> > is not to be applied in the context of the attached policy subject
> > when that alternative is engaged.
> > This would provide clearer semantic (I believe) to borth assertion
> > and policy authors.
> >
> > The attached mark-up of the policy framework specification contains
> > the changes that I believe would
> > be necessary to affect this change.
> >
> > Impact analysis:
> >
> > - The proposed change does not affect the XML syntax
> > - Nor does it impact the semantics of the namespace, therefore the
> > namesapce URI can remain unchanged
> > - It does not affect the processing model (normalization,
> > intersection)
> > - It does not impact testing results to date
> > - It does not affect any of the assertion languages developed to date
> >
> > The related questsion that needs to be asked should we choose to
> > adopt this proposal is:
> >
> >         Does this change affect any implementations?
> >
> > From analysis of the set of test cases, the answer is not clear,
> > because there were no tests that
> > excercised either policy vocabulary or the "will not be applied"
> > semantic. Thus, it would be important that
> > we check our respective implementations to ascertain whether there
> > would be any impact. From an IBM
> > perspective, this change does not impact our implementation.
> >
> >
> >
> > Cheers,
> >
> > Christopher Ferris
> > STSM, Software Group Standards Strategy
> > email: chrisfer@us.ibm.com
> > blog: http://www.ibm.com/developerworks/blogs/page/chrisferris
> > phone: +1 508 377 9295
>
>