client.send(roomid, {}, msg);

##</code><code>##

  $ua->start($tx => sub ($ua, $tx) {
    say 'WebSocket handshake failed!' and return unless $tx->is_websocket;
    $tx->on(message => sub ($tx, $msg) {
      say "WebSocket message: $msg";
      $tx->finish;
    });
    $tx->send('some msg');
  });