• https://stackoverflow.com/questions/8071182/oauth-2-0-php-client-and-server-example

I downloaded the server version (PDO) available for the OAuth 2.0 here: http://code.google.com/p/oauth2-php/

Not sure if it is the best implementation out there honestly.

It is configured and currently returns an error JSON indicating it is waiting for a client to pass it the correct arguments.

Now, it comes with a "lib" folder that has a Client .inc file. Honestly, I am not sure how to use it given there is no PHP example I found in the archive and couldn't find anything online. I found an example for Drupal using this library, but it is a mess given they have their own Drupal-related functionalities as a module.