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Re: Policy alternatives, negation, [Non]AnonResponse assertion and the none URI

From: Tom Rutt <tom@coastin.com>
Date: Mon, 23 Apr 2007 15:42:18 -0400
To: Anish Karmarkar <Anish.Karmarkar@oracle.com>
Cc: Ashok Malhotra <ashok.malhotra@oracle.com>, "public-ws-addressing@w3.org" <public-ws-addressing@w3.org>, ws policy <public-ws-policy@w3.org>
Message-id: <462D0C1A.6010406@coastin.com>

I would like to point out that in my understanding (which is  changing 
"weekly" I must admit)
a missing assertion in a policy means it does not "apply"  This does not 
say negation.

I am having trouble understanding the point Ashok is trying to make.

If assertions are defined as in alterntaive G (constraints over a 
general use of ws addressing) then empty does not imply
negation, but implies the constraint does not apply.

I like alternative G, and I would suggest that we wait for the policy 
group's response to Bob's letter.

Tom R

Anish Karmarkar wrote:
> Ashok,
> So you are saying (I'm rephrasing to get clarity) that:
> "... does not apply .." => one MUST NOT do whatever the missing 
> assertion asked one to do.
> Right?
> If so, the spec needs to be clarified to make it clear. This was not 
> clear to a lot of folks on WS-Addressing.
> Additionally, does this negation effect apply to only top-level 
> assertions or nested assertions as well. IOW, are nested assertions 
> part of the vocabulary.
> One not obvious (not to me) side-effect of this 'negation' is the 
> following:
> Consider the scenario where two very complicated polices are created 
> by the IT department. Let's call them P1 and P2. I'm required to use 
> P1 or P2 on services that are exposed outside the firewall. P1 
> contains an assertion A that is absent in P2. If I advertise P1 only 
> then I have to do whatever A asks me to do. If I advertise P2 only, I 
> may or may not use A (as it is not part of the vocabulary) -- it is up 
> to me. If I advertise a policy that says either of P1 or P2 and P2 is 
> selected, I cannot use A. This is very surprising (at least to me). 
> This does not follow the 'principle of least surprise'. "OR"ing 
> operation in other contexts does not introduce negation based on 
> vocabulary set. I'm curious as to the rationale for this. In any case, 
> guidance and clarification in the spec or the primer would be very 
> useful.
> -Anish
> -- 
> Ashok Malhotra wrote:
>> If you have a Policy that says Assertion A and B then you have to do 
>> A and B.  Since it says nothing about C, you may or may not do C. 
>> However, if A,B and C are all in the Policy Vocabulary (the 
>> assertions contained in the Policy) and you select an alternative 
>> from the Policy that contains only A and B, you may not do C.  Thus, 
>> it is a form of negation.
>> All the best, Ashok
>>> -----Original Message-----
>>> From: Anish Karmarkar [mailto:Anish.Karmarkar@oracle.com]
>>> Sent: Monday, April 16, 2007 2:41 PM
>>> To: Ashok Malhotra
>>> Cc: public-ws-addressing@w3.org; ws policy
>>> Subject: Re: Policy alternatives, negation, [Non]AnonResponse assertion
>>> and the none URI
>>> Ashok,
>>> We discussed this at the ws-addr call today and are waiting to get
>>> clarification from ws-policy WG on the phrase "... assertion will 
>>> not be
>>> applied ...," as to its meaning. It is not clear, to at least some
>>> (many?) member of ws-addr wg, what it means.
>>> We decided to postpone a resolution on this (and related issue) till we
>>> get some direction/resolution from ws-policy wg.
>>> -Anish
>>> -- 
>>> Ashok Malhotra wrote:
>>>> Here is the relevant text from the Policy Framework document:
>>>> [Definition: A policy vocabulary is the set of all policy assertion
>>> types used in a policy.] ... 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.
>>>> All the best, Ashok
>>>>> -----Original Message-----
>>>>> From: public-ws-addressing-request@w3.org 
>>>>> [mailto:public-ws-addressing-
>>>>> request@w3.org] On Behalf Of Anish Karmarkar
>>>>> Sent: Monday, April 16, 2007 9:56 AM
>>>>> To: public-ws-addressing@w3.org
>>>>> Subject: Policy alternatives, negation, [Non]AnonResponse 
>>>>> assertion and
>>>>> the none URI
>>>>> There is view among the WS-Policy wonks (not sure how widely accepted
>>>>> this is or whether the WS-Policy specs explicitly calls this out) 
>>>>> that
>>>>> when there are alternatives present and the selected alternative does
>>>>> not contain an assertion X but another alternative does, then the
>>> effect
>>>>>   of such a selection consists of negation of X.
>>>>> We have two assertions AnonResponse and NonAnonResponse assertions.
>>> Both
>>>>> of them require that the 'none' URI be allowed for the response EPR.
>>>>> Does that mean that negation of any of these implies 'none' must 
>>>>> not be
>>>>> used?
>>>>> If so, that is a problem, none is useful for things like one-way
>>>>> operations that don't use the response EPR for that MEP.
>>>>> Additionally, if one has two alternatives one with AnonResponse only
>>> and
>>>>> one with NonAnonResponse only, then that would be self-contradictory.
>>>>> -Anish
>>>>> -- 

Tom Rutt	email: tom@coastin.com; trutt@us.fujitsu.com
Tel: +1 732 801 5744          Fax: +1 732 774 5133
Received on Monday, 23 April 2007 19:42:23 UTC

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