public function onOpen(WebSocketConnection $connection)
 {
     if (count($this->connections) > 100) {
         $connection->close();
         return;
     }
     $this->connections->pushBack($connection);
 }
 public function addConnection(WebSocketConnection $connection)
 {
     $this->connections->pushBack($connection);
     $connection->send($this->serializeMessage(new SendStateMessage($this)));
 }