Sulu\Component\Websocket\MessageDispatcher\MessageHandlerContext::set PHP Method

    public function set($name, $value)
    {
        $this->parameters->set($name, $value);
    }

 /**
  * Start preview session.
  *
  * @param ConnectionInterface   $conn
  * @param MessageHandlerContext $context
  * @param array                 $msg
  *
  * @return array
  *
  * @throws MissingParameterException
  */
 private function start(ConnectionInterface $conn, MessageHandlerContext $context, $msg)
 {
     // locale
     if (!array_key_exists('locale', $msg)) {
         throw new MissingParameterException('locale');
     }
     $locale = $msg['locale'];
     $context->set('locale', $locale);
     // webspace key
     if (!array_key_exists('webspaceKey', $msg)) {
         throw new MissingParameterException('webspaceKey');
     }
     $webspaceKey = $msg['webspaceKey'];
     $context->set('webspaceKey', $webspaceKey);
     // user id
     if (!array_key_exists('user', $msg)) {
         throw new MissingParameterException('user');
     }
     $user = $msg['user'];
     $context->set('user', $user);
     // content uuid
     if (!array_key_exists('content', $msg)) {
         throw new MissingParameterException('content');
     }
     $contentUuid = $msg['content'];
     $context->set('content', $contentUuid);
     // init message vars
     $template = array_key_exists('template', $msg) ? $msg['template'] : null;
     $data = array_key_exists('data', $msg) ? $msg['data'] : null;
     // start preview
     $this->preview->start($user, $contentUuid, $webspaceKey, $locale, $data, $template);
     return ['command' => 'start', 'content' => $contentUuid, 'msg' => 'OK'];
 }