Did any one here use Sponger cartridge available in virtuoso openlink software? I had installed virtuoso opensource triple store and am currently trying to use the sponger cartridge to convert an Atom feed into RDF/XML. I have an XSLT stylesheet for the transformation. The documentation provided for virtuoso-sponger says that Sponger is in built into SPARQL end point and that if a sparql query is written like say "select ?p from named http://example.com/atomfeed.xml option (get:soft "soft",get:method "GET") where {GRAPH ?g {?s ?p ?o}}", it would via HTTP go the specified link, call the sponger, extract the data and map it to a particular schema using a particular stylesheet. Now is it the GRDDL that should be used to point to the xsl stylesheet ? If I do not have a GRDDL tag in my atom feed how would I call a particular XSLT stylesheet? Can somebody who worked with virtuoso sponger help me in doing this. If you think this is not the relevant form to ask this question can you explain the importance of GRDDL.

Thanks