[gdome]A few comparisons with Xerces-C++

[Paolo Casarini <casarini CS UniBO IT>]

dear folks,
   Luca Padovani - new co-author of Gdome2 and author of
GtkMathView who gave me fundamental helps designing the current state of 
Gdome2 - and I have made a few comparisons between Gdome2 and
Xerces-C++, both for performances and memory occupation. The results of
such tests can be found at:

  http://www.cs.unibo.it/~casarini/gdome2/bench.html

It is important to note that the actual memory occupation of Gdome2
varies according to the number of live references to the tree. The
minimum memory occupation corresponds to the occupation of the libxml2
tree alone (no Gdome2 reference, that is no Gdome2 wrapper allocated).
The maximum memory occupation corresponds to the situation where *each*
node of the tree is referenced (a wrapper allocated for each node).

While it is clear that, in the worse case, Gdome2 has a larger memory
occupation, it has also been proved faster than Xerces, probably because
of the use of "smart pointers" in Xerces. On the other hand, the larger
memory occupation is mostly due to the fact that Gdome2 is just a layer
on top of libxml2 (and many fields in Gdome2 wrappers are used for
connecting the two layers). This gives a more modular architecture, but
can be a drawback where memory occupation is a major issue (especially
when using large XML files). We believe that some effective improvements
can be done, but before going further in this direction, we would like
to know your opinions and your ideas, hoping that some of you will have
the patience (and bravery...) to have a look at libxml2 and Gdome2
source code in order to suggest improvements and design issues. Of
course, we are ready to share our opinions as well.


Bye
   Paolo
--
Paolo Casarini - casarini cs unibo it