title: How to implement an OAuth 2 consumer for FB and G+ and IN and TT
body: <p>Can anyone explain or point to some documentation on the GET / POST requests together with the message bodies + parameters + headers needed for authenticating a consumer with each of the following providers: Facebook, LinkedIn, Google, Twitter?</p>
  
  <p>Note:
  I am looking for framework agnostic steps, required to authenticate an OAuth 2 consumer.</p>