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RE: ANN: xpath1() scheme for XPointer

• To: "'Elliotte Rusty Harold'" <elharo@m...>,<simonstl@s...>,<xml-dev@l...>
• Subject: RE: ANN: xpath1() scheme for XPointer
• From: "Michael Kay" <michael.h.kay@n...>
• Date: Sun, 27 Oct 2002 12:35:10 -0000
• Importance: Normal
• In-reply-to: <p04330103b9e057680bef@[192.168.254.4]>
• Reply-to: <michael.h.kay@n...>

> At 11:01 AM +0100 10/25/02, Michael Kay wrote:
> >It might also aid interoperability to say
> >something explicit about the handling of whitespace-only text nodes.
> 
> What would you need to say about this? XPath is unambiguous about 
> handling this. Perhaps it just needs to be pointed out that 
> whitespace only nodes do count, though I hope by now most XPath users 
> know this.

XPath is defined in terms of a data model. When used in the context of
an XPointer, I think you need to say unambiguously how the data model is
derived from the source (serial) XML. XPath itself (deliberately)
doesn't do that, which can lead to interoperability problems because
different processors construct the data model from the source XML in
different ways: some strip whitespace, some expand XInclude, etc.
> 
> >I'm a little surprised that you seem [from the last sentence 
> of section 
> >3] to see the scheme as providing a way of addressing within an XML 
> >entity, rather than an XML document. In fact, I think it 
> would be most 
> >useful to say that both entity expansion and XInclude 
> processing should 
> >happen before XPath evaluation.
> 
> Entity expansion is a good idea. I don't think the XPath data model 
> really applies unless entities have been expanded. XInclude 
> resolution is trickier. The proper result of applying an XPath 
> expression to a document containing XInclude is completely 
> unambiguous, and it does not involve XInclude resolution.

That's one way of making it unambiguous. The other way of making it
unambiguous is to say that it *does* involve XInclude resolution.
Simon's proposal said neither, and was therefore ambiguous.

Michael Kay
Software AG
home: Michael.H.Kay@n...
work: Michael.Kay@s... 

• References:
  • RE: ANN: xpath1() scheme for XPointer
    • From: Elliotte Rusty Harold <elharo@m...>

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