Has anyone tried to get the Microsoft sample Data Source plugin in the
SDK to work with a protocol specifier other than sample://   ??

I'm trying to use the plugin to service rtsp://  requests as well. I've
modified the URL Prefix field in the registry to "file://" (to match the
base WMS File Data Source plugin), but this does not seem to help.
Although the plug-in is registered, and will service sample://  
requests (also verified through use of  breakpoints in VS), the plugin
does not get invoked at all when rtsp:// requests are sent to the
server and the client immediately gets a "server not available".  Is
there anything special that needs to be done to get the WM Server to
recognize the Sample Data Source plug-in as a component that can
service the rtsp:// requests?

Any help or insight would be most appreciated. Thanks.