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RE: NEW ISSUE (3639) Which policy alternative was selected?

From: Daniel Roth <Daniel.Roth@microsoft.com>
Date: Fri, 1 Sep 2006 15:27:33 -0700
Message-ID: <CACD2E414F77164CA4F324AF9A2094F3026AA552@RED-MSG-70.redmond.corp.microsoft.com>
To: "Ashok Malhotra" <ashok.malhotra@oracle.com>, <public-ws-policy@w3.org>

Hi Ashok,

I've tried to address the issues you identified below:

"Note that there may be more than one alternative in the two policies
that matches and there is no simple algorithm to determine which
alternative is selected."

A policy represents the capabilities and requirements of a provider.  If
the policy contains multiple alternatives, the policy provider is
publicizing that it will honor any of those alternatives for a given
interaction.  A requester is free to use any of these alternatives.  If
the provider cannot process messages that conform to any one of these
alternatives, then its policy is inaccurate.

"There is also the problem of ensuring, in this case, that both parties
select the same alternative from competing, matching alternatives."

Only the requester selects a policy alternative.  The provider must be
ready to honor any of its published alternatives.

"This lack of knowledge makes it difficult for the Policy compliance
engine check whether a message adheres to the Policy it is supposed to."

The policy compliance engine would need to verify that the message
adheres to at least one of the policy alternatives for the given
interaction.  Having the policy in its entirety (not the specific
alternative) is sufficient.  

I hope this helps.

-----Original Message-----
From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Ashok Malhotra
Sent: Tuesday, August 29, 2006 7:36 AM
To: public-ws-policy@w3.org
Subject: NEW ISSUE (3639) Which policy alternative was selected?


TITLE: Which policy alternative was selected?

DESCRIPTION:
A possible Policy processing model is as follows:  the two parties get
access to each other policies (in a manner not specified in the
framework) and select a Policy alternative that that appears in the
Policies of both parties.  This Policy alternative is followed in both
directions.  But there is no mechanism to communicate the selected
alternative to either party.  Note that there may be more than one
alternative in the two policies that matches and there is no simple
algorithm to determine which alternative is selected.  There is also the
problem of ensuring, in this case, that both parties select the same
alternative from competing, matching alternatives.  This lack of
knowledge makes it difficult for the Policy compliance engine check
whether a message adheres to the Policy it is supposed to.


JUSTIFICATION:
The lack of knowledge of the policy alternative selected makes it
difficult to write a Policy
compliance engine.  Also, if more than one Policy alternatives matches
in the two policies, the 
two parties may select different alternatives.


TARGET:  Framework

PROPOSAL:
We need three things:
1. An algorithm to select a single alternative if more than one
alternative in the two policies matches
2. A mechanism to indicate the selected alternative
3. An ability for the message to indicate the policy alternative it is
following


All the best, Ashok
Received on Friday, 1 September 2006 22:28:39 GMT

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