Facebook c＃sdk登录和发布访问令牌到服务器

Question

我正在使用javascript sdk登录并将accessstoken发布到服务器，如facebook c＃sdk入门页面所述。我遇到了一些问题。

1. 它使用auth.authResponseChange，每次触发都会导致重定向循环
2. 如果我将其更改为auth.login，则只有在用户通过我的网站登录时才会调用它。如果他们已经登录fb，则无效。
3. 我如何只将一次发送回服务器并将其存储在会话中？

4. 如果我在服务器上使用oauth身份验证，是否可以将访问令牌传递回javascript sdk？

   FB.Event.subscribe('auth.authResponseChange', function(response) {
       if (response.status === 'connected') {
           // the user is logged in and has authenticated your
           // app, and response.authResponse supplies
           // the user's ID, a valid access token, a signed
           // request, and the time the access token 
           // and signed request each expire
           var uid = response.authResponse.userID;
           var accessToken = response.authResponse.accessToken;
   
           // TODO: Handle the access token
           // Do a post to the server to finish the logon
           // This is a form post since we don't want to use AJAX
           var form = document.createElement("form");
           form.setAttribute("method", 'post');
           form.setAttribute("action", '/FacebookLogin.ashx');
   
           var field = document.createElement("input");
           field.setAttribute("type", "hidden");
           field.setAttribute("name", 'accessToken');
           field.setAttribute("value", accessToken);
           form.appendChild(field);
   
           document.body.appendChild(form);
           form.submit();
   
       } else if (response.status === 'not_authorized') {
           // the user is logged in to Facebook, 
           // but has not authenticated your app
       } else {
          // the user isn't logged in to Facebook.
       }
   });