[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Flexible Schemas (was RE: The task to be solved
Leigh Dodds wrote: ... > > Instead I think it suggests that our approach to writing *schemas* isn't > flexible enough to deal with documents containing an arbitrary mix of > namespaces. I should state up front I don't have any answers here, > I'm just interested in a general discussion. > > The majority of schemas that I've seen assume a fixed set of > elements. These elements may come from zero, one or more namespaces. > The schema is "closed". They're designed to validate a particular > class of documents. > > Some schemas are "open", i.e. they allow "unknown" elements to be > used in the document, and these usually in fairly fixed places (cf: XSD > ANY, XHTML DTD Modularization). However these schemas still seem > to be designed to validate _documents_. They validate the document, > and ignore sections of it, or as with modularization defer to other > schema/dtd modules. > > Yet the scenario you're discussing is one which seems like it could > become increasingly common: we have a mixed namespace document > for which there is no schema. You're asking, how can I validate > these documents? Is there a heuristic for combining together several > schemas to achieve this goal? > > To do this you need to define schemas not only to be open, but also > to be easily fragmented so that portions of it can be applied. I can > imagine doing this with a schematron schema (only apply certain rules/patterns), > but not with a DTD. I also assume there's a way to do this with RELAX NG > and XSD. You then need to apply these fragments to the document to > validate it. > ... > > RDDL only enters this picture as a way to associate a schema, or > fragment thereof with a Namespace URL. Doing something with those > fragments, assuming they're available is something for the validator. > Yes, exactly. If I created any confusion with my statement regarding RDDL support in XSV, my apologies. It is ONLY a mechanism to locate an XML Schema given a namespace URI. A you have said: what one does once the schema is located is ENTIRELY up to the validator/client. Jonathan
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