title: Akka.Net (C#) Publish message to all actors in a Cluster
body: <p>I am trying to use the pub/sub pattern in a cluster.
  The documentation on this is VERY poor.</p>
  
  <p>The scenario I am looking for is:
  1. an actor subscribes to an event.
  2. anywhere in the code, publish a message to all the subscribers on this event in the actor system, without selecting the actors.</p>
  
  <p>From the "existing" documentation, the way to do that is using:
  DistributedPubSub.Get(Context.System).Mediator;</p>
  
  <p>However, once I initiate a Mediator, I get an "association" exception.</p>
  
  <ol>
  <li>What am I missing?</li>
  <li>Can someone point me to a working demo?</li>
  </ol>
  
  <p>Thanks</p>