Re: [xml-dev] DTDs, W3C Schemas, RELAX NG, Schematron?

[Paul Prescod <paul@prescod.net>]

James Clark wrote:
> 
>....
> 
> I agree that the emphasis on named typing in W3C XML Schema is a profound
> difference from RNG.  One interesting question is whether it would be
> possible to build a schema language that supports named typing yet still has
> (at least most of) the simplicity and power of RNG.  However, I still have
> my doubts that named typing is appropriate for XML.  I would speculate that
> named typing is part of what makes use of DCOM and CORBA lead to the kind of
> relatively tight coupling that is exactly what I thought we were all trying
> to avoid by moving to XML.

And insofar as it is important to map from elements to programming
language types, it isn't necessarily clear that this is the role of a
*schema language*. As you suggest, two partners might decide to agree on
syntax (as specified in an XML schema) and yet differ in how they map
those to programming language types. I think we should have the option
of sharing a type-mapping, but it should be a choice separate from
deciding to share a schema. Also, I think a type-mapping language should
probably be more XPath-y to allow (for example) for type mapping based
on attribute values or the referents of links.

 Paul Prescod