[xquery-talk] Constructing namespace nodes

[Michael Kay]

> I suggest you make your case to the W3C committee to convince them 
> that the namespace axis and namespace nodes are first-class parts of 
> the XPath model and should, therefore, be accessible in XQuery.  I 
> haven't heard why XQuery explicitly chose to make the namespace axis 
> unaccessible, rather than making it optional so that some XQuery 
> engines could support it if they wanted to.
>

XQuery 3.0 has the somewhat odd situation that namespace nodes can now 
be dynamically created and added to elements, but they still cannot be 
retrived via the namespace axis. There's strong opposition to the 
namespace axis from some members of the XQuery WG who still seem to 
believe that it's conceptually complex and/or that supporting it will 
cause inefficiency. For retrieving namespaces, the functions 
in-scope-prefixes() and namespace-uri-for-prefix() do provide adequate 
functionality.

There is one valid criticism of the "namespace node" data model, which 
is that it doesn't work well with XQuery Updates. For retrieval, asking 
about in-scope namespaces makes sense. But when you're dealing with 
updates, the idea of adding or deleting a single namespace declaration 
does seem rather simpler than adding or deleting hundreds of namespace 
nodes.

Michael Kay
Saxonica