public abstract void SendSystemMessage(PID pid, SystemMessage sys);
 public void Stop(PID pid)
 {
     SendSystemMessage(pid, new Stop());
 }
 public abstract void SendUserMessage(PID pid, object message, PID sender);
 public Request(object message, PID sender)
 {
     Message = message;
     Sender  = sender;
 }
        public void Request(object message, PID sender)
        {
            var reff = Ref ?? ProcessRegistry.Instance.Get(this);

            reff.SendUserMessage(this, message, sender);
        }
 public override void SendSystemMessage(PID pid, SystemMessage sys)
 {
     Mailbox.PostSystemMessage(sys);
 }