From Stephan Huber,

"Attached you'll find a proposal for using different
protocols. The idea behind the new code is:

1.) plugins/apps register protocols which they can handle. This is done
via osgDB::Registry::registerProtocol(aProtocolName). Plugins register
supported protocols as usual via ReaderWriter::supportsProtocol(..), the
Registry is updated accordingly.

2.) osgDB::containsServerAddress checks first for an appearance of "://"
in the filename and then checks the protocol against the set of
registered protocols via Registry::isProtocolRegistered(aProtocollName)

3.) the other getServer*-functions changed as well, there's even a
getServerProtocol-function


With these changes filenames/Urls get routed to loaded plugins even with
different protocols than 'http'."

src/osgDB/ReaderWriter.cpp

@@ -47,6 +47,7 @@ bool ReaderWriter::acceptsExtension(const std::string& extension) const
 
 void ReaderWriter::supportsProtocol(const std::string& fmt, const std::string& description)
 {
+    Registry::instance()->registerProtocol(fmt);
     _supportedProtocols[convertToLowerCase(fmt)] = description;
 }