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Re: ASN.1 => XML Schema questions

From: Eric van der Vlist <vdv@dyomedea.com>
Date: Tue, 26 Jun 2001 23:20:52 +0200
Message-ID: <3B38FCB4.D97A7B96@dyomedea.com>
To: "K.Kawaguchi" <kohsukekawaguchi@yahoo.com>
Cc: Geoff Elgey <elgey@dstc.qut.edu.au>, xmlschema-dev@w3.org
"K.Kawaguchi" wrote:
> 
> > I know that N! alternatives sounds daunting when performing schema
> > validation -- is this why <all> cannot have repetitions or be nested
> > within a <sequence> ?
> 
> There are algorithms that can validate <all> nested within <all>, or
> whatever (see http://www.thaiopensource.com/relaxng/jing.html for
> example), but it's just that W3C XML Schema decided not to allow them
> for some reason.
> 
> So your options are either
> 
> - stick to W3C XML Schema and make a compromise by using (a|b)* rather
>   than (ab|ba)*.
> - or switch to another schema language that allows you to express what
>   you want.

There is a third possibility that might not be as awful as it seems to
be at first glance... a validation process in 2 phases can be developed:
a XSLT transformation produces a normalized or canonical version of the
document and performs some application dependent checks and a schema
language finishes the job.

In this case, the transformation would "reorder" the sequences of ab|ba
into sequences of ab that can be validated using W3C XML Schema or even
a DTD.

Eric

> regards,
> ----------------------
> K.Kawaguchi
> E-Mail: kohsukekawaguchi@yahoo.com

-- 
Pour y voir plus clair dans la nebuleuse XML...
                                          http://dyomedea.com/formation/
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Eric van der Vlist       http://xmlfr.org            http://dyomedea.com
http://xsltunit.org      http://4xt.org           http://examplotron.org
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Received on Tuesday, 26 June 2001 17:20:56 GMT

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