Ruby Webrick HTTP 身份验证

我怎样才能做同样的身份验证工作这一页 http://microjet.ath.cx/webrickguide/html/HTTP_Authentication.html使用这样的子类：

        class Configuration < HTTPServlet::AbstractServlet
        def do_GET (request, response)
            SOMETHING....
        end
        end

    server = HTTPServer.new(:Port => 666)
    server.mount "/conf", Configuration
    trap "INT" do server.shutdown end
    server.start

如果你以几乎相同的风格来做，那么对我来说似乎工作正常，例如

class Configuration < HTTPServlet::AbstractServlet
    def do_GET(req, res)
        HTTPAuth.basic_auth(req, res, "My Realm") {|user, pass|
          # block should return true if
          # authentication token is valid
          user == 'user' && pass == 'topsecret'
        }
        res.body = 
          "Authenticated OK\n"
    end
end

您遇到什么问题了？