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RE: Generic proposal for enganging MTOM in WSDL 2.0

From: Jonathan Marsh <jonathan@wso2.com>
Date: Tue, 5 Dec 2006 13:17:32 -0800
To: <paul.downey@bt.com>, <ryman@ca.ibm.com>
Cc: <www-ws-desc@w3.org>
Message-ID: <00ee01c718b2$c7de7a00$3401a8c0@DELLICIOUS>

To capture Asir's idea expressed at the end of the last telcon, here's an
updated proposal to allow Canon to indicate MTOM engagement using standard
(or pre-standard) technologies.

Original Proposal (from Paul):

WSDL 2.0 provides an extension attribute which MAY be used to indicate a
WS-Policy attachment is "vanilla", only contains a single set of assertions
and does not contain any compositors, e.g.:

  <Policy wsdli:simpleAssertions="true">
    <wsoma:OptimizedMimeSerialization /> 
    <wsa:UsingAddressing />
  </Policy>

A non-Policy aware processor may process the wrapped assertions as just
another hop in their XPaths, and yet continue to interoperate with
processors which support the whole of WS-Policy.

Updated Proposal (based on Asir's idea):

An implementation may support a subset of Policy that consists of the policy
wrapper appearing as a child of <wsdl:binding> or <wsdl:endpoint> elements,
and containing only the OptimizedMimeSerialization assertion [1] (no
compositors allowed), or indeed any list of assertions supported by the
implementation.  The Policy element can be marked as wsdl:required="true".

  <Policy>
    <wsoma:OptimizedMimeSerialization /> 
  </Policy>

Advantages:
1) No new syntax needed.
2) No changes to specs at all!
3) Profile can be processed by a fully conformant WS-Policy processor.
4) Obviates need to describe the interaction of wsdli:simpleAssertions and
wsdl:required.
5) Can be defined for multiple versions of Policy.
6) Supports any assertions supported by the implementation (just like
WS-Policy.)  This includes a possible future version of an MTOM assertion.
7) Isn't open to unintended side-effects (what evil uses could
wsdli:simpleAssertions be put to?)

Disadvantages;
1) Doesn't provide any standards status to such a profile.
2) Doesn't provide any machine-readable indication that the profile is in
use.

[1]
http://schemas.xmlsoap.org/ws/2004/09/policy/optimizedmimeserialization/opti
mizedmimeserialization-policy.pdf

Jonathan Marsh - http://www.wso2.com - http://auburnmarshes.spaces.live.com
 

> -----Original Message-----
> From: paul.downey@bt.com [mailto:paul.downey@bt.com]
> Sent: Thursday, November 30, 2006 3:48 AM
> To: jonathan@wso2.com; ryman@ca.ibm.com
> Cc: www-ws-desc@w3.org
> Subject: RE: Generic proposal for enganging MTOM in WSDL 2.0
> 
> Hi Jonathan,
> 
> > The risk I saw is that you can't take an off-the-shelf WSDL with
> embedded
> > policy and simply add the new annotation and expect it to work with
> Canon's
> > implementation.  You'd have to do a fairly severe restructuring, losing
> the
> > maintainability provided by the indirection.
> 
> I don't think that's the user story ..
> 
> > If that's not the goal, and one would instead be taking an off-the-shelf
> > WSDL with MTOM extension and adding WS-Policy,
> 
> .. I didn't think so ..
> 
> > or crafting a WSDL from
> > scratch that would work with both,
> > then this proposal makes more sense.
> 
> .. yes, that's the use-case I'm thinking of.
> 
> Maybe we can hear from Canon
> given it's them we're trying to help.
> 
> > It is unfortunate that there will be two ways to express an extension -
> >   <my:extension/>
> > and
> >  <foobar wsdli:simpleAssertions="true">
> >    <my:extension/>
> >  </foobar>
> >
> > Are there any ambiguities with this?  Namely, what if I understand both
> > <foobar> and <my:extension>.  Does the processing of
> wsdli:simpleAssertions
> > turn off the "understanding" of foobar?  Another way to ask this is -
> what
> > does the component model look like?  Both from a foobar aware processor
> and
> > a my:extension processor.
> 
> I'd imagine that's precisely the same as saying:
> 
>   <my:extension value="on">
>   <my:extension value="off">
>   <my:extension>
>   ...
> 
> or even:
> 
>   <ex:useTheForce>
>   <wsp11:Policy>
>      <ex:useTheForce/>
>   </wsp11:Policy>
>   <wsp15:policy>
>      <ex:useTheForce/>
>   </wsp15:Policy>
> 
> If you are going to say something twice
> make sure it's the same thing, otherwise you need
> some context dependent rules, and of course Policy is
> pretty good for composition.
> 
> So I don't think WSDL 2.0 needs to say anything new here.
> 
> Paul
Received on Tuesday, 5 December 2006 21:24:12 GMT

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