title: Mapping SignalR connections to users
body: <p>Consider a web application like facebook, that can send realtime notifications to users.</p>
  
  <p>What is the best way, using <a href="https://github.com/SignalR/SignalR/wiki">asp.net SignalR</a>, to keep track of which connection ids belong to which  user, even if the user disconnects, or reconnects later ?</p>