[R] RSXML - Parsing XML Documents on Internet

[larsenmtl@comcast.net]

R Users -

I asked about this a few months ago and never did quite figure it out, so with more information, allow me to try again.

If I use the following code:

library(xml)
xmlTreeParse("http://home.comcast.net/~larsenmtl/xmlTestDoc.xml", isURL = TRUE)
 
I receive this error:
Error in xmlTreeParse("http://home.comcast.net/~larsenmtl/xmlTestDoc.xml"",  : 
        error in creating parser for http://home.comcast.net/~larsenmtl/xmlTestDoc.xml"

Now I know that xmlTreeParse uses the libxml facilities for downloading and parsing off the web.   Along with one of our network people, I did some packet sniffing and it looks like libxml doesn't go through our proxy server (it tries to directly connect to the above URL), which is the reason for the error.  Is there anyway to force it through the proxy?  Am I missing some setting or option?  If I download the xml file and parse it locally it works without error.

Please Note that the URL is valid and I can open it in my browser.  Also note that I must start R with the --internet2 option so it'll use our proxy server.  

Details:
Windows 2000
R1.9.1
RSXML 0.97-0
libxml2-2.4.13 distribution for Windows

I also tried this on a Mandrake 9.2 box with R1.9.1, XML0.95-6, and libxml2 2.6.13.  Results were the same but with the additional error message:
I/O warning: falied to load external entity "http://...."

Thanks,

Mark Larsen