protected function findSchemaFile($fileName)
    {
        // check if we got a specific schema file we have to use, otherwise use the default one
        $this->schemaFile = realpath(__DIR__ . '/../../../../../') . DIRECTORY_SEPARATOR . self::DEFAULT_XML_SCHEMA;
        $fileName = pathinfo($fileName, PATHINFO_FILENAME);
        if (isset($this->schemaFiles[$fileName])) {
            $this->schemaFile = $this->schemaFiles[$fileName];
        }
    }