XOM API for Processing XML with Java

[Elliotte Harold <elharo AT metalab.unc.edu>]

Steve Loughran wrote:

> My particular need is this: I need to get a list of all currently
> visible (prefix,namespace) tuples on an element so that I can then to
> my own qname to element mapping, even after the node I was using has
> been reparented.

OK. That's one I haven't heard before, and I can see that. In the early 
days when we were hashing out the exact namespace model for XOM, one of 
the things we considered was maintaining all namespaces in scope when an 
element was deleted, but that was just too ugly. For instance, when an 
element node is inserted at a new position in the tree, does it 
undeclare all prefixes inherited from its ancestors?

I tried to follow the principle of least surprise here based on my best 
guess of what most people would expect or want most of the time, but I'm 
afraid namespaces in XML are just too fundamentally weird to avoid 
surprising some of the people some of the time. Frankly if XOM can avoid 
surprising most of the people most of the time, it's doing really well. :-)

I can see that the grid spec you're referring to uses namespaces in 
element content, but I still don't have a full use case. Why do you need 
 to move elements from one namespace scope to a different namespace 
scope? If you can explain that, you might convince me.

Two more questions:

1. When you move an element from point A to point B does this happen 
during a depth first search from the root to the element you're moving?

2. Do you just need all the namespaces when you detach, or do you also 
need them when you insert? This asks whether you allow a reinserted 
element to inherit namespaces from its new parent as well as its old. 
(Actually in XML 1.0 namespace prefixes can't be undeclared so the point 
is probably moot.)

--
Elliotte Rusty Harold  elharo AT metalab.unc.edu
XML in a Nutshell 3rd Edition Just Published!
http://www.cafeconleche.org/books/xian3/
http://www.amazon.com/exec/obidos/ISBN=0596007647/cafeaulaitA/ref=nosim