xrd which will later be printed. Must be * implemented by child classes. */ abstract protected function setXRD(); public function __construct(RequestStack $requestStack) { parent::__construct($requestStack); if ($this->request->headers->get('format', null) === null) { $this->request->headers->set('format', $this->default_mimetype); } $this->xrd = new XML_XRD(); } public function handle(Request $request): array { $this->setXRD(); return ['xrd' => $this->xrd, 'default_mimetype' => $this->default_mimetype]; } }