How to Integrate Asp.Net application in Facebook

Someone asked me how to create facebook app day before yesterday and he wanted to integrate existing asp.net webpage in this facebook app. I was not much aware about facebook integration but got to know that facebook doesn’t have any api for asp.net to integrate webpage instead they have for php and python. So I googled and then find very good dotnet toolkit for facebook app which is from Microsoft (Facebook Developer Kit). We can integrate desktop or web app using this toolkit. So I thought I should make a sample app and share on this platform.
Below are some steps":
Before creating facebook app you need to have facebook account.
Setting up Facebook App

• To create facebook app click on Developer section 
• Click on Set up New App button.
• Agree Facebook terms and click on Create App

• Put Security Check keywords.
• Click on Submit.
• Fill basic information about app.

• Click on Facebook Integration tab.
• Put Name of Canvas page.
• Before putting URL of webpage of your website, I want to show how your page can get callback from facebook app. So first we create webpage in our website:
• Create asp.net website in Visual studio.
• Add reference of Facebook.dll from “C:\Program Files\Coding4Fun\Facebook\Binaries”. This dll will be placed after installing Facebook Developer kit on your machine.
• Create instance of FacebookService object. you can copy facebook app api key and secret key from application page on facebook in source code.

put above values in FACEBOOK_API_KEY and FACEBOOK_SECRET constants respectively.
you can get user_id of facebook who requested this application by calling

1.string userId = Session["Facebook_userId"] as String;

you can also get many information about user like name, sex, location,friends etc.

1.User usr=_fbService.GetUserInfo();

Source Code

01.using System;

02.using Facebook;

03.public partial class Facebook_ConnectFacebook : System.Web.UI.Page

04.{

05.Facebook.Components.FacebookService _fbService = new Facebook.Components.FacebookService();

06.private const string FACEBOOK_API_KEY = "191856207506775";

07.private const string FACEBOOK_SECRET = "820c0b05b14a09365e072c8d37a8c49f";

08. 

09.protected void Page_Load(object sender, EventArgs e)

10.{

11._fbService.ApplicationKey = FACEBOOK_API_KEY; _fbService.Secret = FACEBOOK_SECRET;

12._fbService.IsDesktopApplication = false;

13.string sessionKey = Session["Facebook_session_key"] as String;

14.string userId = Session["Facebook_userId"] as String;

15. 

16.// When the user uses the Facebook login page, the redirect back here

17.// will will have the auth_token in the query params

18. 

19.string authToken = Request.QueryString["auth_token"];

20. 

21.// We have already established a session on behalf of this user

22.if (!String.IsNullOrEmpty(sessionKey))

23.{

24._fbService.SessionKey = sessionKey; _fbService.UserId = userId;

25.}

26.// This will be executed when Facebook login redirects to our page        

27.else if (!String.IsNullOrEmpty(authToken))

28.{

29._fbService.CreateSession(authToken);

30.Session["Facebook_session_key"] = _fbService.SessionKey;

31.Session["Facebook_userId"] = _fbService.UserId;

32.Session["Facebook_session_expires"] = _fbService.SessionExpires;

33.}

34.// Need to login        

35.else

36.{

37.Response.Redirect(@"http://www.Facebook.com/login.php?api_key=" + _fbService.ApplicationKey + @"&v=1.0\");

38.}

39. 

40.User usr = _fbService.GetUserInfo();

41.string t = string.Format("User Name:{0}, Sex:{1}, Location: {2}", usr.Name, usr.Sex, usr.CurrentLocation.City);

42.Response.Write(t);

43.}

44.}

Testing

Now we are done with coding. Its time for testing.

• Run your website.
• Put webaddress of your webpage in facebook developer section as canvas URL.
• Canvas type should be IFrame.

• Click on Save changes.
• now Facebook app has created.

• Now open app url like http://apps.facebook.com/testneeraj/ on browser .
• First time authToken will not authorize from facebook because you need to agree on “Allow Access” information.

• Click on facebook banner.
• It will ask Request for Permission. Click Allow.

• It will show all basic information of user on webpage.

• After that you can publish your app but having restriction from facebook that your application should 10 active member per month.