public function setFile($path)
    {
        if (empty($path) || !is_readable($path)) {
            /**
             * @see Zend_Auth_Adapter_Http_Resolver_Exception
             */
            require_once 'Zend/Auth/Adapter/Http/Resolver/Exception.php';
            throw new Zend_Auth_Adapter_Http_Resolver_Exception('Path not readable: ' . $path);
        }
        $this->_file = $path;

        return $this;
    }