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Re: document base uri

From: Romain Deltour <rdeltour@gmail.com>
Date: Thu, 22 Sep 2011 17:16:01 +0200
To: Geert Josten <geert.josten@daidalos.nl>
Message-Id: <B17615F1-C206-4976-B72E-163336BEE712@gmail.com>
Cc: XProc Dev <xproc-dev@w3.org>
The XProc model is based on the XML Information Set [1], which does  
allow a base URI on both document and element items. As Norm correctly  
pointed out on the XProc Comment list [2], the problem is with XML  
processing instructions which can have a base URI too. Adding an  
xml:base attribute to the root element shouldn't change the base URI  
of sibling PIs... so my proposal wouldn't work.

It seems we all agree that a 'p:base-uri' step changing the base URI  
of the document would be a nice addition.


[1] http://www.w3.org/TR/xproc/#infoset-conformance
[2] http://lists.w3.org/Archives/Public/public-xml-processing-model-comments/2011Sep/0003.html
Le 22 sept. 11 à 12:59, Geert Josten a écrit :

> Hi Romain,
> Interesting! I had similar problems when I tried to rely on base-uri  
> to keep track from which file certain (processed) trees came from. I  
> was forced to use base-uri(/*) to work around this problem. I am not  
> sure though that setting a xml:base attribute on the root element to  
> change the base-uri of the document node is the best solution.
> First of all, I am curious what the XML Base spec would say about  
> the difference between the two (base-uri of document node versus  
> xml:base on root element), does it distinguish between the two?
> Secondly, I would make more sense to me to have a p:change-base-uri  
> step that *would* allow changing the base-uri property of the  
> document node.
> Kind regards,
> Geert
> -----Oorspronkelijk bericht-----
> Van: xproc-dev-request@w3.org [mailto:xproc-dev-request@w3.org]  
> Namens Romain Deltour
> Verzonden: donderdag 22 september 2011 0:52
> Aan: XProc Comments
> CC: XProc Dev
> Onderwerp: document base uri
> Hi,
> It seems the general approach for XProc steps is that if an attribute
> named "xml:base" is added (or changed), the base URI of the underlying
> element MUST be updated [1].
> However, there seems to be no simple way [*] to change the base URI of
> a *document* flowing through a pipeline. This makes the no-arg p:base-
> uri() function (returning the context document base URI) very brittle
> whenever @xml:base is manipulated.
> I think it would be better to say: if an attribute named "xml:base" is
> added (or changed), the base URI of the underlying element MUST be
> updated ; if the underlying element is the root element, the base URI
> of the document MUST be updated.
> Note that the introduction of section 7 [2] is confusing for the same
> reason:
> 	"When a step in this library produces an output document, the base
> URI of the output is the base URI of the step's primary input document
> unless the step's process explicitly sets an xml:base attribute (...)"
> Comments welcome!
> Romain.
> [1] http://lists.w3.org/Archives/Public/public-xml-processing-model-comments/2009Jan/0040.html
> [2] http://www.w3.org/TR/xproc/#std-components
> [*] I tried several solutions:
>    a) adding an @xml:base (e.g. with p:add-attribute) affects an
> element, not the document node.
>    b) using a p:xslt with @output-base-uri and an identity XSLT seems
> to work with XSLT 1.0-enabled processors (e.g. Calumet), not with XSLT
> 2.0-enabled ones (e.g. Calabash).
> I suppose it's because Calumet uses XSLT 1.0 ("An XSLT 1.0 step should
> use the value of the output-base-uri as the base URI of its output")
> and Calabash XSLT 2.0 (which doesn't specifies, as far as I
> understood, that the base output URI sets the base URI of an
> implicitly constructed final result tree).
>    c) I could get something working by using an XSLT 2.0 identity
> that writes on an explicit xsl:result-document, then discarding the
> main result port, wrapping/unwrapping the secondary sequence port to
> get the single result document.
> I attached some XProc documents showing the approaches described  
> above.
> --
> Romain Deltour, Software Developer
> The DAISY Consortium
> http://www.daisy.org
Received on Thursday, 22 September 2011 15:16:34 UTC

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