Re: [xml] Using Xpath with default namespace and null prefix

[Daniel Veillard <veillard redhat com>]

On Mon, Feb 08, 2010 at 02:03:06PM +0100, Daniel Veillard wrote:
> On Mon, Feb 08, 2010 at 01:14:22PM +0100, Iñaki Baz Castillo wrote:
> > RFC 4825 is a pain as it reuses Xpath 1.0 with some restrictions and additions 
> > (as the "application default namespace" which allows the Xpath deviation I 
> > told) so a XML library implementing Xpath 1.0 is not enough valid to implement 
> > a XCAP client/server :(
>
>   You will have to capture the XPath expression and mofify them before
> calling libxml2, there won't be any way around.
>
> The fundamental reason why allowing something like "//foo" to mach an

  to *not* match

> element in the default namespace is that this namespace can change
> wherever in the document
>
> <foo>
>  <foo xmlns="http://example1.com/foo"/>
>  <foo xmlns="http://example2.com/foo"/>
> </foo>
>
> //foo would then returns 3 elements with completely different semantic
> coming from different vocabularies. XML being designed for being
> extensible XPath had to put a safeguard. Matching in XPath is designed
> as a match on the tuple [Namespace URI name , element name] , that's
> made 100% clear in the XPath spec, the prefix, present or not, is
> completely irrelevant in the XPath query.

Daniel

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