Hi Ola!
you might also want to have a look at how the SPICE - browser does the  
das communication.
http://www.efamily.org.uk/software/dasclients/spice/ 
devel_dasrequests.shtml
Cheers,
Andreas
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Andreas Prlic      Wellcome Trust Sanger Institute
                               Hinxton, Cambridge CB10 1SA, UK
			 +44 (0) 1223 49 6891