protected function initialize($serial)
    {

        // load the actual status
        $status = $this->getRegistryProcessor()->getAttribute($serial);

        // query whether or not the configured source directory is available
        if (!is_dir($sourceDir = $status[RegistryKeys::SOURCE_DIRECTORY])) {
            throw new \Exception(sprintf('Configured source directory "%s" is not available!', $sourceDir));
        }

        // set the source directory
        $this->setSourceDir($sourceDir);
    }