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Re: Validation of documents using internal XLinks [Was:] Dependency of XPointers upon DTD

From: Eric van der Vlist <vdv@dyomedea.com>
Date: Fri, 08 Sep 2000 16:36:30 +0200
Message-ID: <39B8F96E.D13F4E7B@dyomedea.com>
To: "Eve L. Maler" <eve.maler@east.sun.com>
CC: www-xml-linking-comments@w3.org, Daniel Veillard <Daniel.Veillard@w3.org>
Eve,

Thanks for your answers.

I'd like to insist on the XSLT issue...

"Eve L. Maler" wrote:
> 
> At 09:25 AM 9/8/00 +0200, Eric van der Vlist wrote:
> >While you can validate (using XML Schemas) and resolve the link using
> >XSLT the user defined link, you can't validate the XLink alternative (at
> >least using XML Schemas as defined today) and, since XSLT doesn't
> >support variable XPath expressions, you can't even resolve the link
> >using a standard XSLT processor.
> 
> I'm not following.  You would need an "XPointer application layer" in the
> second scenario anyway, which is supposed to help you do this.  And in what
> way would a standard XSLT engine not help you implement one?  (BTW, that's
> another subject -- mixing linking and styling -- on which we hope to make
> some analysis public soon...)
> 

In practice, I don't see clearly how this "XPointer application layer"
will fit in the picture and these tools are still missing.

Anyway, I think we will need to be able to use a XPointer expression
within stylesheets to retrieve some or all the nodes pointed by a
XPointer.

Unfortunately, XSLT doesn't allow "dynamic" XPaths and you can't write
something like :

    <xsl:apply-template select="$xpath"/>

making it impossible to implement XPointer resolution using standard
XSLT.

A solution could be to allow variable XPath evaluations. This has been
discussed at different places and there seem to be strong arguments
against it.

Another solution could be to enhance the XPath "document" function
(currently accepting URIs as a parameter) to support XPointer.

This would unfortunately not be very coherent with the current behavior:
document("") is pointing to the stylesheet itself and to be XPointer
conformant document("#xpointer()") should point to a node in the current
XML document...

This issue has not been included in the XSLT 1.1 requirement document
which has been recently published.

Would it help if I cross posted to xsl-editors ?

Eric
-- 
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Eric van der Vlist       Dyomedea                    http://dyomedea.com
http://xmlfr.org         http://4xt.org              http://ducotede.com
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Received on Friday, 8 September 2000 11:02:23 GMT

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