JSON-RPC: Player.Open an HTTP URL

I want to play HTTP URLs on XBMC via JSON-RPC. In pre-EDEN version of the API I have used the XBMC.Play method.
How can I achieve that?

I tried setting the URL with Player.Open (as the "path" argument) and then Player.PlayPause. Unfortunately it doesn't work and in the log file I get "GetDirectory - Unable to get http directory". I guess it is described somewhere but I wasn't able to find anything on the forums nor the wiki.