public function getModule($moduleName) {
        $moduleName = strtolower($moduleName);
        if (isset(self::$_modules[$moduleName])) {
            return self::$_modules[$moduleName];
        } else {
            try {
                return $this->loadModule($moduleName);
            }
            catch (\Exception $e) {
                throw new ModuleException("Cannot find requested module: $moduleName");
            }
        }
    }