title: websocket scalability
body: <p>I have looked around a bit on websockets, and I have a pretty concrete question:
  Can websockets actually be scaled over different servers, or are they always limited to one single server?</p>
  
  <p>It seems that this is an issue I've repeatedly bumped into in the docs I have found, but maybe they were incomplete or things evolved. It seems for example as heroku even doesn't support websockets at all(?)</p>