public function onSubscribe(ConnectionInterface $conn, $topic)
    {
        $this->console->info("onSubscribe: {$conn->WAMP->sessionId} topic: $topic {$topic->count()}");

        if (!array_key_exists($topic->getId(), $this->subscribedTopics)) {
            $this->subscribedTopics[$topic->getId()] = $topic;
            $this->console->info("subscribed to topic $topic");
        }
    }