Prooph\ServiceBus\QueryBus::dispatch PHP Method

    public function dispatch($query)
    {
        $deferred = new Deferred();
        $promise = $deferred->promise();
        $actionEvent = $this->getActionEventEmitter()->getNewActionEvent();
        $actionEvent->setTarget($this);
        $actionEvent->setParam(self::EVENT_PARAM_DEFERRED, $deferred);
        $actionEvent->setParam(self::EVENT_PARAM_PROMISE, $promise);
        try {
            $this->initialize($query, $actionEvent);
            if ($actionEvent->getParam(self::EVENT_PARAM_MESSAGE_HANDLER) === null) {
                $actionEvent->setName(self::EVENT_ROUTE);
                $this->trigger($actionEvent);
            }
            if ($actionEvent->getParam(self::EVENT_PARAM_MESSAGE_HANDLER) === null) {
                throw new RuntimeException(sprintf("QueryBus was not able to identify a Finder for query %s", $this->getMessageName($query)));
            }
            $finder = $actionEvent->getParam(self::EVENT_PARAM_MESSAGE_HANDLER);
            if (is_string($finder) && !is_callable($finder)) {
                $actionEvent->setName(self::EVENT_LOCATE_HANDLER);
                $this->trigger($actionEvent);
            }
            $actionEvent->setName(self::EVENT_INVOKE_FINDER);
            $this->trigger($actionEvent);
            if (!$actionEvent->getParam(self::EVENT_PARAM_MESSAGE_HANDLED)) {
                throw new RuntimeException(sprintf('Query %s was not handled', $this->getMessageName($query)));
            }
            $this->triggerFinalize($actionEvent);
        } catch (\Exception $ex) {
            $failedPhase = $actionEvent->getName();
            $actionEvent->setParam(self::EVENT_PARAM_EXCEPTION, $ex);
            $this->triggerError($actionEvent);
            $this->triggerFinalize($actionEvent);
            //Check if a listener has removed the exception to indicate that it was able to handle it
            if ($ex = $actionEvent->getParam(self::EVENT_PARAM_EXCEPTION)) {
                $actionEvent->setName($failedPhase);
                $deferred->reject(MessageDispatchException::failed($actionEvent, $ex));
            }
        }
        return $actionEvent->getParam(self::EVENT_PARAM_PROMISE);
    }

 /**
  * @param RequestInterface $request
  * @param ResponseInterface $response
  * @param callable $next
  * @return ResponseInterface
  */
 public function __invoke(RequestInterface $request, ResponseInterface $response, callable $next)
 {
     $users = [];
     $this->queryBus->dispatch(new GetAllUsers())->then(function ($result) use(&$users) {
         $users = $result;
     });
     return new HtmlResponse($this->templates->render('page::user-list', ['users' => $users]));
 }