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RE: Section 5 vs Schema

From: Andrew Layman <andrewl@microsoft.com>
Date: Fri, 25 Jan 2002 09:53:26 -0800
Message-ID: <C3729BBB6099B344834634EC67DE4AE103DA34F9@red-msg-01.redmond.corp.microsoft.com>
To: "XML Protocol Discussion" <xml-dist-app@w3.org>
+1
The xsi:type attribute is only needed if the type of the element in the
XML instance is more specific than can be determined by reference to a
schema (or other equivalent metadata).

-----Original Message-----
From: Martin Gudgin [mailto:marting@develop.com] 
Sent: Friday, January 25, 2002 9:30 AM
To: Marc Hadley
Cc: XML Protocol Discussion
Subject: Re: Section 5 vs Schema

Woah there! Are you asserting that in the absence of a schema you *MUST*
use
xsi:type? If so, I'm afraid I violently disagree. To my mind, the *ONLY*
case for using xsi:type is if the type of the thing being sent is not
know
until runtime;

    // Java
    void Fn ( Object o );

    // C++
    void Fn ( void* p );

    // VB
    Sub Fn ( v As Variant )

In all other cases you have something that is typed, and that is enough.

Gudge

----- Original Message -----
From: "Marc Hadley" <marc.hadley@sun.com>
To: "Martin Gudgin" <marting@develop.com>
Cc: "XML Protocol Discussion" <xml-dist-app@w3.org>
Sent: Friday, January 25, 2002 3:00 PM
Subject: Re: Section 5 vs Schema


> 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 12:53:58 GMT

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