def get_resolve_url(self, did_bytes):
        """Return a did value and value type from the block chain event record using 'did'.

        :param did_bytes: DID, hex-str
        :return url: Url, str
        """
        data = self._did_registry.get_registered_attribute(did_bytes)
        if not (data and data.get('value')):
            return None

        return data['value']