XOM API for Processing XML with Java

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

Steve Loughran wrote:

> I hear bad things about the performance impact of integrating
> namespace support into things, things like DOM and XPath. Has anyone
> some quantified numbers or should I just make them up?

Make them up of course. :-)

My concern was not with speed. Memory was an issue, and a quantifiable 
one, but it was probably solvable. The nasty problems were conceptual. 
For instance, if we model namespaces in scope, what happens when we 
disconnect an element from its parent? Does it retain inherited 
namespaces or not? What happens when you insert it in a new tree?

We addressed a lot of similar issues in handling xml:base, and that was 
extremely painful. We did the best we could, but I'm still not sure any 
answer we came up with was always correct. Namespaces have the same 
problem times 10. XPath-style namespaces have the same problem times a 
hundred.

The whole namespace declaration attribute syntax is nice and unambiguous 
as long as you're only talking about complete, well-formed XML documents 
that never change. It completely blows up as soon as you begin slicing 
and dicing documents and removing nodes from and inserting nodes into a 
document. Static documents are fine. Dynamic ones just aren't. :-(

--
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