Datasource notifications via nsIRDFXMLParser

I am loading remote rdf into an In-Mem-DS with the 
nsIRDFXMLParser.parseAsync() method where I pass the returned 
nsIStreamListener into an nsIHttpChannel.asyncOpen() method..

var nsIStreamListener = nsIRDFXMLParser.parseAsync( Ds, baseUri );

[...]
nsIHttpChannel.requestMethod = "GET";
nsIHttpChannel.notificationCallbacks = nsIRequestor;
nsIHttpChannel.asyncOpen( nsIStreamListener, null );

My nsIProgressEventSink methods on the channel gets called correctly 
whilst the HTTP request proceeds, but no methods on the 
nsIStreamListener get called. Is this because it's a remote Uri?

Would an nsIRDFXMLSinkObserver work if multiple parseAsync() methods 
were called against the same datasource on different threads (eg. 
multiple-updates)?


A composite-ds's GetDataSource() won't work as the request has arguments 
encoded in the Uri, and so generates a new ds for each request.

Cheers,