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

From: Anthony Nadalin <drsecure@us.ibm.com>
Date: Wed, 2 Aug 2006 20:56:19 -0500
To: "Asir Vedamuthu" <asirveda@microsoft.com>
Cc: "Asir Vedamuthu" <asirveda@microsoft.com>, "Daniel Roth" <daniel.roth@microsoft.com>, "Prasad Yendluri" <prasad.yendluri@webmethods.com>, public-ws-policy@w3.org, public-ws-policy-request@w3.org
Message-ID: <OF00CEDE64.AFE2CA8E-ON862571BF.000A7ABA-862571BF.000AA661@us.ibm.com>
The example below does have nesting, as there is TransportBinding assertion
that has an AlgorithmSuite assertion and so on and so on

Anthony Nadalin | Work 512.838.0085 | Cell 512.289.4122


                                                                           
             "Asir Vedamuthu"                                              
             <asirveda@microso                                             
             ft.com>                                                    To 
             Sent by:                  "Asir Vedamuthu"                    
             public-ws-policy-         <asirveda@microsoft.com>, "Prasad   
             request@w3.org            Yendluri"                           
                                       <prasad.yendluri@webmethods.com>,   
                                       "Daniel Roth"                       
             08/02/2006 04:09          <daniel.roth@microsoft.com>,        
             PM                        <public-ws-policy@w3.org>           
                                                                        cc 
                                                                           
                                                                   Subject 
                                       RE: NEW ISSUE: "Policy              
                                       Alternatives" and "Policy" need     
                                       proper def  inition                 
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




In the example below, it is not clear to me where assertions start and end.
As described in Section 4.3.2 [1], a nested policy expression is a policy
expression that is a child element of a policy assertion element:

"Any policy assertion MAY contain a nested policy expression. The schema
outline for a nested policy expression is:

<Assertion ¡K>
  ¡K
  ( <wsp:Policy ¡K> ¡K </wsp:Policy> )?
  ¡K
</Assertion>"

In the example below, it does not look like any of these assertions have
nested policy expressions. Was this intentional? The normative text in
Section 4.3.2 seems to be clear that this must be the case.

[1]
http://www.w3.org/TR/2006/WD-ws-policy-20060731/#Policy_Assertion_Nesting


Regards,rporation

________________________________________
From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Asir Vedamuthu
Sent: Wednesday, August 02, 2006 7:12 AM
To: Prasad Yendluri; Daniel Roth; public-ws-policy@w3.org
Subject: RE: NEW ISSUE: "Policy Alternatives" and "Policy" need proper def
inition

RE the text of the specification is not explicit enough for this

A full worked out example that demonstrates how the current definitions are
ambiguous or not explicit enough is the best way to move forward on this.

Regards,
________________________________________
From: Prasad Yendluri [mailto:prasad.yendluri@webmethods.com]
Sent: Tuesday, August 01, 2006 5:36 PM
To: Asir Vedamuthu; Prasad Yendluri; Daniel Roth; public-ws-policy@w3.org
Subject: RE: NEW ISSUE: "Policy Alternatives" and "Policy" need proper def
inition

Hi Asir,

> I noticed that your example policies do not use any nested policy
expression.

Section 4.3.3 defines:

Equivalence
wsp:Policy is equivalent to wsp:All

So, for readability, I have not explicitly put wsp:policy brackets around
things and used wsp:All.

If my ?examples have been, cy 1:tlyOne>?????-- assertion 7 -->
?? </wsp:ExactlyOne>Example Policy 2:

<wsp:All>!-- assertion 1 -->
??? <!-- assertion 2 -->
? </wsp:ExactlyOne>???? . . . .-->
??????? <wsp:ExactlyOne>??? 6 -->
????????? <!-- assertion 7 -->
?????? </wsp:ExactlyOne>e>
</wsp:All>

Would you not then have the same policy alternates for Policy 1 and the
nested policy in policy 2?
I understand the way you came up with the production of the alternatives
for each policy and agree that is the correct way to arrive at them.? The
point of the issue however is that, the text of the specification is not
explicit enough for this. What makes a nested alternative in a Policy
specification not an alternative of the parent policy, when policy is only
defined to be ¡§a collection of policy alternatives¡¨? The nested policy and
hence the embedded alternative is part of the same ¡§collection¡¨ is it not?

Regards,
Prasad

-----Original Message-----
From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Asir Vedamuthu
Sent: Tuesday, August 01, 2006 5:05 PM
To: Prasad Yendluri; Daniel Roth; public-ws-policy@w3.org
Subject: RE: NEW ISSUE: "Policy Alternatives" and "Policy" need proper def
inition

Hi Prasad,

Thank you for writing down these examples. Let us look at the two policy
expressions in your e-mail below.

Policy 1 has two alternatives:
A1 = {assertion 6, assertion 8}
A2 = {assertion 7, assertion 8}

Policy 2 has six alternatives:
A3 = {assertion 1, assertion 4}
A4 = {assertion 2, assertion 4}
A5 = {assertion 1, assertion 5, assertion 6}
A6 = {assertion 1, assertion 5, assertion 7}
A7 = {assertion 2, assertion 5, assertion 6}
A8 = {assertion 2, assertion 5, assertion 7} each policy assertion in one
alternative is compatible with a policy assertion in the other and
vice-versa. None of the above policy alternatives are compatible.

Two policies are compatible if a policy alternative in one is compatible
with a policy alternative in the other. Policy 1 and Policy 2 are
incompatible because none of the policy alternatives in Policy 1 is
compatible with a policy alternative in Policy 2.

Just as expected, these two policies are incompatible. I noticed that your
example policies do not use any nested policy expression.

I hope this helps.

PS: I¡¦ll update your entry in Bugzilla.

Regards,

________________________________________
From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Prasad Yendluri
Sent: Monday, July 31, 2006 5:32 PM
To: Daniel Roth; Prasad Yendluri; public-ws-policy@w3.org
Subject: RE: NEW ISSUE: "Policy Alternatives" and "Policy" need proper def
inition

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).K>Assertion>

There is generally no ambiguity until we run into further specifications
that state things like ¡§Two policies are compatible if an alternative in
one is compatible with an alternative in the other.¡¨

Suppose you have the following two Policy specifications:ple Policy 1:lternative A
¡÷? <!-- assertion 7 -->
?? </wsp:ExactlyOne>rtion 8 -->? <!¡XAlternative B ¡÷
</wsp:All>???? Example Policy 2:

<wsp:All>!¡XAlternative 1 Top level ¡÷??? <!-- assertion 2 -->
? </wsp:ExactlyOne>tlyOne>? <!¡XAlternative 2 Top level ¡÷on 4 -->
??? <wsp:All> ¡XAlternative 3 Nested
¡÷<!¡XAlternative 4 Nested ¡÷->
????????? <!-- assertion 7 -->
?????? </wsp:ExactlyOne>urns out <!¡XAlternative A ¡÷ in Example Policy 1 is compatible with (same
definition as) the ¡§nested¡¨ policy alternative marked
<!¡XAlternative 4 Nested ¡÷ in Example Policy 2.

Then using the definition, ¡§Two policies 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 defines a ¡§policy¡¨ to be, ¡§a
collection of policy alternatives¡¨
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 is a
potentially empty collection of policy alternatives.¡¨

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¡¨ 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 is a logical construct which represents a potentially
empty collection of policy assertions. 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. al ¡V 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

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Received on Thursday, 3 August 2006 02:00:35 UTC

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