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Re: Non-deterministic content model
- From: Rick Jelliffe <firstname.lastname@example.org>
- To: email@example.com
- Date: Sat, 16 Jun 2001 16:23:40 +0800
From: "Jeni Tennison" <firstname.lastname@example.org>
> > XML Schema forces deterministic model groups, so you can't use that.
Or, rather, "W3C's XML Schemas 1.0 provides deterministic model groups so
you can't use that."
- there are other XML schemas than W3C's
- future versions may relax the features, if there is popular demand etc.
- "force" makes it sound like we have no choice, but we can choose other
schema languages whenever we want.
This last one is worth keeping in mind, it may be that each stage in an
information flow is optimal for a different schema language (or paradigm!).
So if one has limited resources, one probably picks whichever schema
language or paradigm will have the broadest impact, knowing the solution is
less than perfect in each stage. But if one has a few more resources,
creating stage-dependent schemas might be worthwhile.
For example, one might have one DTD for accepting data from contractors and
data conversion houses, but a much stricter one for new documents
created -house. Or you might use XML Schemas for autogenerating Java
interfaces, but use Schematron to check that incoming data is consistent
with more complex rules. Or you might use RELAX for your XSL validation,
but DTDs for the resulting documents.
I don't expect there will many people using XML Schemas -and- RELAX -and
XDR/SOXetc. in the same house. Personally, I find it very difficult to
keep different grammar conventions in mind.
Perhaps we need a "Common Structures" proposal, which would provide the
union of XML Schemas and RELAX NG, probably using XML Schemas syntax. Like
RELAX Core, I guess. Kawaguchi-san's article on XML.com is probably a good
place to start (without endorsing it.) Any volunteers?