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WS-Policy and interopearbility (Was: policy vocabulary, will not be applied, oh my!)

From: Sergey Beryozkin <sergey.beryozkin@iona.com>
Date: Wed, 9 May 2007 11:52:35 +0100
To: "'Dale Moberg'" <dmoberg@us.axway.com>, <public-ws-policy@w3.org>
Cc: "'David Orchard'" <dorchard@bea.com>, "'Daniel Roth'" <Daniel.Roth@microsoft.com>, "'Christopher B Ferris'" <chrisfer@us.ibm.com>
Message-ID: <EMEA-EMS1N3Isam5R4r00000254@emea-ems1.ionaglobal.com>
Hi

 

> Second, I am also puzzled about the emergence of the concern with
interoperability.

 

IMHO it's a very legitimate concern. WS-Policy may enhance the chances for
the interoperability.

May be it's not the main goal of the specs, but the positive side-effect can
be achieved. 

For example, various custom WSDL extensors can be turned into WS-Policy
extensors and then even standardized.

Other example is that often the capabilities are sometimes bundled into the
(WSDL) endpoint extensors, say, security-related ones.

Extracting such capabilities into standalone WS-Policy extensors can only
increase the chance for the interoperability between third-party

clients of a given service

 

Thanks, Sergey 

 

 

 

  _____  

From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Dale Moberg
Sent: 08 May 2007 23:16
To: public-ws-policy@w3.org
Cc: David Orchard; Daniel Roth; Christopher B Ferris
Subject: RE: policy vocabulary, will not be applied, oh my!

 

First, I prefer Monica and Ashok's proposed revisions. I can understand
their proposal. I share Mr. Orchard's concerns about trying to finesse the
difficulties with the original AIN.

 

Second, I am also puzzled about the emergence of the concern with
interoperability.

 

Is it the intention that the ws-policy framework somehow ensure that when
there exist policy alternatives in common between proposer's policy and
consumer's policy, then the proposer and consumer will interoperate? It
seems that there might be a lot of "behavior" not covered by any policy
domain expression that could cause interoperability problems (like
extensions, etc), so it will be very difficult to defend the idea that
agreeing on the same policy alternative ensures interoperability. 

 

Anyway, isn't the WS-I organization one primary forum where conformance
profiles and promotion of WS interoperability is to occur? Our charter only
says that

The Working Group may also:

*	Author a primer that includes guidance on the use of policy
expressions to facilitate Web services interoperability and guidelines for
authoring policy assertions, and 

I don't see that either the framework or attachment documents are devoted to
interoperability. It would be nice if the ws-policy framework provided a
general solution to WS interoperability, but I think that is taking on some
big problems that are not explicitly in scope. Possibly I misunderstand,
however; so I would like to see an explicit statement of the design intent
that connects the policy framework ambitions with WS interoperability. Maybe
that way we can understand the NOBI option's rationale.

 

 

 

  _____  

From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of David Orchard
Sent: Tuesday, May 08, 2007 2:46 PM
To: Daniel Roth; Ashok Malhotra; Asir Vedamuthu; Christopher B Ferris;
public-ws-policy@w3.org
Subject: RE: policy vocabulary, will not be applied, oh my!

 

I don't get it.  The very precise sentence that you state "If a behavior
isn't implied, then it shouldn't be applied if you want to interop" says to
me AIN.  

 

Now MAYbe you are saying 

AIN: "If a behavior isn't implied, then it MUST not be applied"

and NOBI: "If a behavior isn't implied, then it shouldn't be applied " 

and someother acronym: "If a behavior isn't implied, then it may or may not
be applied as there is no implied behaviour" 

 

is that where we are at?  Then you are disambiguating between AIN and NOBI
by MUST vs SHOULD?

 

Cheers,

Dave


  _____  


From: Daniel Roth [mailto:Daniel.Roth@microsoft.com] 
Sent: Tuesday, May 08, 2007 2:40 PM
To: David Orchard; Ashok Malhotra; Asir Vedamuthu; Christopher B Ferris;
public-ws-policy@w3.org
Subject: RE: policy vocabulary, will not be applied, oh my!

Hi David,

 

NOBI simply means that an alternative implies the behaviors that are
asserted and No Other Behaviors are Implied.  If a behavior isn't implied,
then it shouldn't be applied if you want to interop.  

 

Chris' proposal gets us out of the mess of having to consider policy
vocabularies or absent assertions (AIN stuff) in order to understand what an
alternative implies you have to do in order to interop.

 

Daniel Roth

 

 

From: David Orchard [mailto:dorchard@bea.com] 
Sent: Tuesday, May 08, 2007 1:43 PM
To: Daniel Roth; Ashok Malhotra; Asir Vedamuthu; Christopher B Ferris;
public-ws-policy@w3.org
Subject: RE: policy vocabulary, will not be applied, oh my!

 

Dan,

 

I'm confused about your terms and language.  there are the acronyms NOBI and
NOIB, which I think are the same.  Assuming that, it seems that there's been
a terminology swizzle so that NOBI has become AIN.  AFAICT, your "For
example" is an example of AIN.  

 

Can you tell me how NOBI is different than AIN now?  

 

Cheers,

Dave

 


  _____  


From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Daniel Roth
Sent: Tuesday, May 08, 2007 1:35 PM
To: Ashok Malhotra; Asir Vedamuthu; Christopher B Ferris;
public-ws-policy@w3.org
Subject: RE: policy vocabulary, will not be applied, oh my!

Hi Ashok,

 

Chris' proposal is actually exactly what I meant by NOBI.  An alternative
should express exactly those behaviors that are needed for interop and
nothing else should be done.  

 

For example, if I have an alternative that says I require message security,
then requesters should not also enable transport security and expect to
interoperate.

 

Chris' proposal looks good to me.

 

Daniel Roth

 

From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Ashok Malhotra
Sent: Tuesday, May 08, 2007 11:42 AM
To: Asir Vedamuthu; Christopher B Ferris; public-ws-policy@w3.org
Subject: RE: policy vocabulary, will not be applied, oh my!

 

So, Asir, just to be clear, this position is different from the NOIB (No
Implied Behavior) that Dan espoused on last Wednesday's call.

 

All the best, Ashok 


  _____  


From: public-ws-policy-request@w3.org
[mailto:public-ws-policy-request@w3.org] On Behalf Of Asir Vedamuthu
Sent: Tuesday, May 08, 2007 9:22 AM
To: Christopher B Ferris; public-ws-policy@w3.org
Subject: 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 <http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_assertion>
assertions.] 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
<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_assertion_type>
assertion types used in a policy.] [Definition: A policy alternative
vocabulary is the set of all policy
<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_assertion_type>
assertion types within the policy
<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_alternative>
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
<http://www.w3.org/TR/2007/CR-ws-policy-20070330/#Optional_Policy_Assertions
> 4.3.1 Optional Policy Assertions 

I would propose the following change: 

[Definition: A policy alternative is a potentially empty collection of
policy <http://www.w3.org/TR/2007/CR-ws-policy-20070330/#policy_assertion>
assertions.] 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
> 
> 
Received on Wednesday, 9 May 2007 10:54:02 GMT

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