public function put($cardData)
    {
        if (is_resource($cardData)) {
            $cardData = stream_get_contents($cardData);
        }

        // Converting to UTF-8, if needed
        $cardData = DAV\StringUtil::ensureUTF8($cardData);

        $etag = $this->carddavBackend->updateCard($this->addressBookInfo['id'], $this->cardData['uri'], $cardData);
        $this->cardData['carddata'] = $cardData;
        $this->cardData['etag'] = $etag;

        return $etag;
    }