Higher level protocols for websockets
I ran across WAMP recently. When I built my DC++ client who's primary GUI is a jquery/jquery ui web app connected to the twisted python backend via websocket I had to create something just like this. Later reading over the JSON RPC 2.0 spec I realized you could just use their format and leverage json rpc libs already written.
Small note: you might want to remove the "jsonrpc" key from the request and response to save some bytes.
There is also this: Cutting Down Bandwidth with JSON Alternatives