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

From: Ashok Malhotra <ashok.malhotra@oracle.com>
Date: Fri, 8 Sep 2006 05:13:21 -0700
To: "Daniel Roth" <Daniel.Roth@microsoft.com>, "public-ws-policy@w3.org" <public-ws-policy@w3.org>
Message-ID: <20060908051321685.00000002764@amalhotr-pc>

Hi Dan:
You said ...
> If the policy contains multiple alternatives, the 
> policy provider is publicizing that it will honor any of 
> those alternatives for a given interaction.

This is a possible interpretation.  I think we shd discuss.

But, still, we have some questions.  Let me summarize.

The situation we are discussing is where both endpoints have policies
and policy matching is used to determine acceptable alternatives.

Q1.  If there are multiple matching alternatives, which one is selected?
The above is a possible answer to this problem.

Q2. When a message is received, which alternative from among the acceptable
alternatives was applied? 

Here is a proposal for Q2.  

- A new policy is constructed containing only the selected alternative.
- The message points to this policy in a standard manner.


All the best, Ashok
 

> -----Original Message-----
> From: Daniel Roth [mailto:Daniel.Roth@microsoft.com] 
> Sent: Friday, September 01, 2006 3:28 PM
> To: Ashok Malhotra; public-ws-policy@w3.org
> Subject: RE: NEW ISSUE (3639) Which policy alternative was selected?
> 
> 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, 8 September 2006 12:15:10 GMT

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