title: Communication between multiple servers
body: <p>How could a network of servers communicate with each other?</p>
  
  <p>For example, if <em>Client A</em> connects to <em>Server A</em>, how would the other servers be informed of this? I'm guessing you would need a "central" server, but how would it be implemented?</p>
  
  <p>I'm really dumbfounded on this, so any help would be nice :)</p>