[Twisted-Python] map Url to function

Hi, I started playing around with twisted.web and want to map the Url to function calls with parameters. For example http://myserver.net/mainhandler/somefkt/parama/paramb should be call some 'mainhandler'. This should be a script which gets '/somefkt/parama/paramb' and knows what to do with it. What's the easiest way to do this? regards, Achim