collaborative editing in ruby on rails - architectural approach?

Question

In our app, we are considering to enable collaborative online editing. It is a graphic application heavily relying on javascript for creating mind-map-like structures.

The first obvious candidate is to use websockets.

Users come to the site to create those maps. I have looked at em-websocket which seems to start an own process, but

 EventMachine.run {

         EventMachine::WebSocket.start(:host => "0.0.0.0", :port => 9876) do |ws|

it seems there is not much of context information there; people may be editing different maps at the same time! So my current guess is to

• for every map being edited on, a new WebSocket server is started on a different port

• as this would entail control of the WebSocket life-cycle, I was thinking to spawn a Thread for every such WebSocket server:

  #on map create/edit: Thread.new do EventMachine.run {

           EventMachine::WebSocket.start(:host => "0.0.0.0", :port => 9876) do |ws|
         ....
     end
  

What do people think on this approach? Is this reasonable? Any other suggestions? Thank you!