public function message_room($room_id, $from, $message, $notify = false,
                               $color = self::COLOR_YELLOW,
                               $message_format = self::FORMAT_HTML) {
    $args = array(
      'room_id' => $room_id,
      'from' => $from,
      'message' => $message,
      'notify' => (int)$notify,
      'color' => $color,
      'message_format' => $message_format
    );
    $response = $this->make_request('rooms/message', $args, 'POST');
    return ($response->status == 'sent');
  }