Re: cannot find the namespace declarations from an extension function

Adrian Herscu schrieb:

>> 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

Hi Adrian!

Seven disjunct kinds of nodes in XPath 1.0 (and 2.0), among which we
find attribute nodes and namespace nodes.

> 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"!

Yes, at the XML syntax level - not, however, in the XPath data model.

Probably best explained historically. First, XML syntax. Then, in
January 1999, XML Namespaces. In November 1999, XSLT and XPath 1.0.

With XML, the syntax came first. Later, various data models were devised
to work with an abstraction of this XML syntax, maybe dropping parts of
it (like the physical structure, entities), maybe conserving parts
(ID-typed attributes), maybe adding stuff not originally present in XML
(W3C XML Schema and PSVI).

So the XPath 1.0 data model is a view of XML that channels the special
xmlns attributes into namespace nodes and plain attributes into
attribute nodes.

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

You're right. I said the namespace declaration attributes wouldn't show
up among the attributes, neither in DOM nor in XDM. For XDM, that was
correct, but for DOM, it wasn't. Sorry for misleading you.

I was led to think and say so because I was used to the version of the
DOM API offered by LibXML2, which maybe isn't a strict *implementation*
of the *specification*. Whatever it is, it doesn't list the namespace
declaration attributes among the ordinary attributes.

I asked on the Xerces-Java list for clarification.

DOM: Are namespace declaration attributes real attributes?
http://markmail.org/thread/4cxxce3ny5hb5qmo

It seems DOM is more of a moving target with three levels and many
options, at least in level 3, one of which is whether or not to include
the namespace declaration attributes among the ordinary attributes. See
this reply I got:

Re: DOM: Are namespace declaration [...] - Michael Glavassevich
http://markmail.org/message/en7dkrkejkzuug4o

So it *seems* to me now that for DOM Level 2, namespace declaration
attributes are ordinary attributes, while for DOM Level 3 they may get
special treatment. (But maybe some expert can clarify further.) For
XPath, at any rate, they're not attributes any more. I guess you could
see this as an increasingly strict adoption and tight integration of XML
namespaces.

Cheers,

Michael Ludwig