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   Re: [xml-dev] Re: Flexible Schemas (was RE: [xml-dev] The task tobe solv

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On Sat, 2002-01-19 at 19:57, Dare Obasanjo wrote:
> I believe the thrust of Nicolas' question is where to find the RDDL document
> for an XML file that utilizes names from multiple namespaces. No one has
> proposed a *concrete* answer to that question yet although the designers of
> RDDL may consider this to be beyond the design goals of RDDL which is
> reasonable.
> For instance the following is the first element in an annotated XSD mapping
> schema for creating XML views of relational data in SQL server 2000
> <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema";
>             xmlns:dt="urn:schemas-microsoft-com:datatypes"
>             xmlns:sql="urn:schemas-microsoft-com:mapping-schema">
> The question is where will one locate the metadata/resources/etc for
> documents of this type? 

Ah.  It's that mythical "document type" again.  Okay, not precisely
mythical, as developers have gone out of their way to create
descriptions of such types which may contain a mash of different

RDDL can only tell you about the parts - one doc per namespace, if
you're lucky.  Some of those parts may attempt to tell you about the
whole, as the RDDL spec itself does.  A better approach - but one which
relies on much more modular (and mathematical) schema approaches than
the dominant ones (DTD, W3C XML Schema) - lets each namespace tell about
itself, and then those parts can be combined.

The algorithms for such combination are defined for RELAX, TREX, and
RELAX NG.  Schematron seems like it would be conducive to such
combination.  Results with other languages may vary.

Similarly, you could use transformations identified in RDDL to attempt
to convert everything to a single namespace.  Might be interesting.

Simon St.Laurent
Ring around the content, a pocket full of brackets
Errors, errors, all fall down!


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