Implementing OAuth 2.0 in a Facebook Environment

Facebook makes implementing OAuth 2.0 easy (and easier with libraries and SDKs), so after you know the URLs to call, it's just a matter of writing the code on your server to handle the requests.

Here's how a sample Facebook OAuth 2.0 flow works:

1. Register your application.

   Go through the application setup process (see Chapter 7). After that is done and you've set up your Web site URL and domain, you are given an application ID and secret. Note that information, because you need to copy and paste it later.

2. Redirect the user to https://www.facebook.com/dialog/oauth.

   Pass to it your application ID in a parameter called client_id and a callback URL that you want to process and get the access token when the user is done logging in. This URL should be passed to a redirect_uri parameter. So, your URL should look something like https://graph.facebook.com/oauth/authorize?client_id=...&redirect_uri=... (passing in the appropriate values as specified).