From a cursory look, it seems you use websocket to communicate with phantom. Neat!!

Is there a minimal program available that shows this interaction?

Yes, it uses xmlrpc (node-xmlrpc) for communication between RobotFramework and Node, and websockets (socket.io) for communication between Node and PhantomJS (which didn't bundle http-server when I started).

I'm sorry to not have a separate websockets-example, but there's really nothing special in using websockets with phantom.