XOM API for Processing XML with Java

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

After investigating this further, I'm fairly convinced that the 
performance gain Wolfgang found is real, but I don't think my initial 
hypothesis as to where that came from is correct. The "slow path" is 
doing more than simply looking for characters that need to be escaped. 
It's also counting characters for purposes of line breaks and indents 
and so forth; and I think most of the speed gain in this proposal comes 
from avoiding that. The failing unit tests post-patch all seem to 
indicate places where the the fast path failed to update fields the slow 
path would have caught.

I've had a FastSerializer class in my pantry (experimental code I don't 
necessarily make public) for a while now, and it shows numbers on my 
system that are close to what this patch from Wolfgang provides; not 
quite as fast but within 20%, and definitely faster than the usual 
Serializer. FastSerializer is not a subclass of Serializer. It's a 
complete reimplementation that only does UTF-8 and provides no line 
breaking or indenting or other pretty-printing features. Possibly 
something like this needs to be published, but  don't think it's a 
replacement for the standard Serializer class.

There is still about a 20% improvement from Wolfgang's work beyond what 
my own FastSerializer does. I'm not sure where that's coming from. I 
need to explore the differences between the two classes a little more to 
see what he may have done that I didn't.

However, whichever way we go, I don't think this patch can work with the 
existing Serializer. It breaks the pretty printing too badly. What it 
makes clear though is just how much pretty printing (even the 
possibility of it, whether you do it or not) costs in serialization 
time. It might be worth releasing a much simpler, non-configurable 
serializer.

--
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