XML parsing under R / Extracting nodes’ values

Hi,
I have an XML file which contains among other nodes :

===myXMLfile.xml===
(?)
<nbRelations>2</nbRelations>
<nbActors>2</nbActors>
(...)
<nbRuns>5</nbRuns>
<nbStep>2000</nbStep>
(?)
===End file===
I need to extract those values and to make them R variables such as:
nbRelations = 2
nbActors = 2

nbRuns = 5
nbSteps = 2000

I read the help and have seen the examples of the xml package, it
seems that I need to use xmlTreeParse() function but I don't know how
exactly as I'm not an R advanced programmer, please can anyone show me
how to do that explicitly ?

Any help would be much appreciated

Thanks,

Abdel
University of Boumerd?s
Algeria