public function load($url)
    {
        if (is_readable($url) === false) {
            $msg = "The PHP document located at '${url}' is not readable or does not exist.";
            throw new PhpStorageException($msg, PhpStorageException::READ);
        }

        try {
            // Will return $rootcomponent.
            require $url;
            $this->setDocumentComponent($rootcomponent);
            $this->setUrl($url);
        } catch (Exception $e) {
            $msg = "A PHP Runtime Error occured while executing the PHP source code representing the document to be loaded at '${url}'.";
            throw new PhpStorageException($msg, PhpStorageException::UNKNOWN, $e);
        }
    }