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Re: Section 5 vs Schema

From: Marc Hadley <marc.hadley@sun.com>
Date: Fri, 25 Jan 2002 15:00:59 +0000
Message-ID: <3C51732B.8070807@sun.com>
To: Martin Gudgin <marting@develop.com>
CC: XML Protocol Discussion <xml-dist-app@w3.org>
The ETF discussed this issue in a recent telcon and would like to 
propose a change to section 3.4 of the current editors draft[1] to 
lessen the schema bias in the examples by showing the mapping from 
programming language compound types to SOAP encoding.

e.g. the first example in section 3.4.1 shows an instance of a book 
structure and a schema that describes the structure. This would be 
replaced with a C language struct definition and a SOAP encoding 
serialisation of the structure, e.g.

BEGIN EXCERPT

The following structure:

struct Book
{
    char *author;
    char *preface;
    char *intro;
} book = {"Henry Ford", "Preface text", "Intro Text"};

would be encoded as follows without a schema

<Book xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:enc="http://www.w3.org/2001/12/soap-encoding">
    <author xsi:type="enc:string">Henry Ford</author>
    <preface xsi:type="enc:string">Preface text</preface>
    <intro xsi:type="enc:string">Henry Ford</intro>
</Book>

or as follows if a schema is available

<e:Book xmlns:e="http://example.org/2001/12/books">
    <e:author>Henry Ford</e:author>
    <e:preface>Preface text</e:preface>
    <e:intro>Henry Ford</e:intro>
</e:Book>

END EXCERPT

Comments, flames etc.

Marc (on behalf of the ETF)

[1] http://www.w3.org/2000/xp/Group/1/10/11/soap12-part2.html

Martin Gudgin wrote:

>SOAP 1.2 Part 2 Section 4[1] ( old section 5 ) defines a set of encoding
>rules for mapping from programmatic type systems to XML.
>
>There was some discussion on the last editors conference about how to deal
>with issue 17[2] regarding the schemas that appear in section 5. I took an
>action to start discussion about this on this list. Please note I will be on
>holiday from today and will not be back until the New Year so will not be
>able to actively participate until then, hopefully you'll all have nailed
>the issue by then!
>
>One suggestion was that section 5 actually defines an implicit schema so
>each mapping from some programmatic type essentially defines a schema type.
>This seems reasonable but at the same time feels a little odd. We have
>section 5 because when SOAP 0.9, 1.0 and 1.1 were written XML Schema was not
>done, we didn't have an XML based type system. So we had to start from a
>type system we did have. So Section 5 defines a set of rules for mapping
>from programmatic type systems iuntNow that XML Schema is done it is
>possible to define the messages being exchanged entirely in XML Schema
>without reference to any programmatic type system. Mapping to the
>programmatic type system ( if any ) at either end of the exchange is an
>implementation detail.
>
>So, given that we have XML Schema, does it make sense to infer a schema from
>some other type system?
>
>And if it does, what do we do about examples in the spec. It seems very
>strange to say 'we start from a programmatic type system' and then only show
>schemas! We are defining a language binding, even if we never show a Java
>class or a C struct or whatever.
>
>OK, that's it. I hope the discussion is fruitful, I'll read through it when
>I get back from holiday.
>
>Regards
>
>Martin Gudgin
>DevelopMentor
>
>
>
>[1] http://www.w3.org/TR/2001/WD-soap12-part2-20011002/#soapenc
>[2] http://www.w3.org/2000/xp/Group/xmlp-issues.html#x17
>
Received on Friday, 25 January 2002 10:01:09 GMT

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