如何将CAS与ASP.NET登录控件一起使用

Question

我现在正在使用ASP.NET登录控件来验证用户登录到我的网站的身份。我想改用CAS来登录。在登录页面上，我做了如下操作：

 protected void Page_Load(object sender, EventArgs e)
{
    //redirect to login page if user isn't login to CAS
    if (Request.QueryString["ticket"] == null)
    {
        string service = Request.Url.GetLeftPart(UriPartial.Path);
        Response.Redirect("https://cas.hou.edu.vn/cas/login?service=" + service);
    }
    //if user logged in to CAS, send request to validate and get the response
    else
    {
        string ticket = Request.QueryString["ticket"].ToString();
        string service = Request.Url.GetLeftPart(UriPartial.Path);
        var request = WebRequest.Create("https://cas.hou.edu.vn/cas/serviceValidate?service=" + service + "&ticket=" + ticket) as HttpWebRequest;

        XmlDocument xmlDoc = new XmlDocument();
        using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
        {
            xmlDoc.Load(response.GetResponseStream());
        }
        XmlNodeList authFail = xmlDoc.GetElementsByTagName("cas:authenticationFailure");

        if (authFail.Count > 0)
        {
            Debug.WriteLine(authFail[0].InnerText);
        }
        else
        {   
            XmlNodeList authSuccess = xmlDoc.GetElementsByTagName("cas:authenticationSuccess");
            //Username
            string userId = authSuccess[0].FirstChild.InnerText;

        }
    } 

成功验证到CAS Server后，我得到响应并具有用户名。您能告诉我如何自定义登录控件以使用该用户名登录。 谢谢！！