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[i48]: XML Protocol WG Issues list discussion

From: David Ezell <David_E3@Verifone.Com>
Date: Tue, 20 Mar 2001 18:04:17 -0500
Message-ID: <472E220BA79DD11186340060B06B38D905BD7F8A@tpantmail1.ssr.hp.com>
To: "'xml-dist-app@w3.org'" <xml-dist-app@w3.org>
At the face to face meeting in Cambridge (February 26 - 27) I agreed
to begin the discussion of Issue 48 in [1], raised in an email to 
xml-dist-app [2].


    "The XML Protocol should allow applications to include custom
     encodings for data types used for parameters and results in
     RPC messages."

The SOAP encodingStyle attribute [5] can be used to used to indicate 
arbitrary serialization rules within a SOAP message. Section 5 [3] of 
the specification also states that "use of the data model and encoding 
style described in [the section describing the default SOAP encoding] is 
encouraged but not required; other data models and encodings can be used 
in conjunction with SOAP."

To my reading, the point being made here is that the XML Protocol 
requirements don't go as far as SOAP/1.1 in terms of defining or encouraging 
special encoding vocabularies.

I would strongly urge that we keep the current wording, and go no farther
in "blessing" any specific type of encoding.  As a possible amelioration
we should *at most* reference the SOAP/1.1 specification, section 5 [4] as
a useful encoding for RPC.

Encoding rules outside those described by XML per se are application semantics, 
and are hence best left out of scope for XML Protocol [6].  Encoding rules 
represent an agreement between applications to interoperate in ways not directly

prescribed or describable by XML Infoset.  Additionally, the encoding rules are 
based on older RPC architectures, and are arguably only applicable in situations

which represent ports of legacy services created using COM, CORBA, or RMI.

More importantly, type definitions in XML documents and how they map to 
application programming languages is an issue best left to implementations 
of content model information sets, such as the XML Schema post validation 
infoset.  Leaving the issue there helps assure maximum "composability" 
(borrowing Paul Cotton's phrase) with other W3C specifications as well
as with outside specifications.

Best regards,
David Ezell

[1] http://www.w3.org/2000/xp/Group/xmlp-issues.html
[2] http://lists.w3.org/Archives/Public/xml-dist-app/2001Jan/0193.html
[3] http://www.w3.org/TR/SOAP/#_Toc478383512 <http://www.w3.org/TR/SOAP/ 
[4] http://www.w3.org/TR/SOAP/#_Toc478383512 <http://www.w3.org/TR/SOAP/
[5] http://www.w3.org/TR/SOAP/#_Toc478383495 <http://www.w3.org/TR/SOAP/ 
[6] N.B. the adoption of multi-part MIME encoding is a separate issue, 
    as I believe that such encodings are currently viewed as "bindings".
Received on Tuesday, 20 March 2001 18:09:06 UTC

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