Re: cannot find the namespace declarations from an extension function

Michael Ludwig wrote:
> Adrian Herscu schrieb:
>> Michael Ludwig wrote:
>>>> Hmmm... It appears that the parser completely ignores all 'xmlns'
>>>> attributes. The interesting thing is that it reads attributes from
>>>> other non-null namespaces.
>>>
>>> The xmlns may look like an attribute, but it really isn't. It's a
>>> namespace declaration, which happens to use attribute syntax.
> 
>> http://www.w3.org/TR/xml-names/#ns-decl
>>
>> [Definition: A namespace (or more precisely, a namespace binding) is
>> declared using a family of reserved attributes. Such an attribute's
>> name must either be xmlns or begin xmlns:. ...]
>>
>> Hence a namespace declaration is an attribute with special meaning,
>> but still just an attribute.
> 
> Well, I'd say, both are right, depending on which view you take :-)
> 
> But on this list the view should probably be Xalan, hence XSLT and the
> XPath Data Model. A namespace declaration attribute isn't an attribute
> in XDM, because it's not on the attribute axis. The fact that namespace
> declaration serialization happens to take attribute form doesn't matter.
> 
>>> That's why it doesn't show up among the attributes, neither in DOM
>>> nor in XDM (XPath Data Model).

Seems like XDM is related to XPath 2.0.
The data model in XPath 1.0 is described at 
http://www.w3.org/TR/xpath#data-model

According to http://www.w3.org/TR/xpath#namespace-nodes

This means that an element will have a namespace node:
     * for every attribute on the element whose name starts with xmlns:;
     * for every attribute on an ancestor element whose name starts 
xmlns: unless the element itself or a nearer ancestor redeclares the prefix;
     * for an xmlns attribute, if the element or some ancestor has an 
xmlns attribute, and the value of the xmlns attribute for the nearest 
such element is non-empty

They are called "attributes"!
Also in DOM2 Core there is nothing that suggests that "namespace 
attributes" are not just regular attributes.


>>
>> The Xerces DOM parser recognizes xmlns: prefixed attributes as
>> attributes. The problem was with the DTM parser used by Xalan.
> 
> Here's a small, standalone, and off-topic script in PHP using LibXML2,
> where the attributes don't show up. But you're right, using Xerces they
> do show up. So I guess DOM (which level?) requires them to show up. Does
> anyone know whether and, if so, where the correct behaviour is
> specified?
> 
> Michael Ludwig
> 
> milu@colinux:~/Werkstatt/php > expand -t2 ns-attr.php
> <?php
> $docstr = '<x:Urmel xmlns="urn:x-U" xmlns:x="urn:x-X" y="3" z="4"/>';
> $dom = new DOMDocument;
> $dom->loadXML( $docstr);
> $elm = $dom->documentElement;
> if ( $elm->hasAttributes() ) {
>   $attlist = $elm->attributes; # DOMNamedNodeMap
>   for ( $i = 0; $node = $attlist->item($i); $i++ ) {
>     echo $node->name, "\n";
>   }
> }
> 
> milu@colinux:~/Werkstatt/php > php ns-attr.php
> y
> z
>