<?phprequire_once 'facebook.php';$appapikey = 'asdfasdf9';$appsecret = 'asdfdasfas536';$facebook = new Facebook($appapikey, $appsecret);$user = $facebook->require_login();//[todo: change the following url to your callback url]$appcallbackurl = 'http://effacebook.solutions-lab.net/';//catch the exception that gets thrown if the cookie has an invalid session_key in ittry { if (!$facebook->api_client->users_isAppAdded()) { $facebook->redirect($facebook->get_add_url()); }} catch (Exception $ex) { //this will clear cookies for your application and redirect them to a login prompt $facebook->set_user(null, null); $facebook->redirect($appcallbackurl);}?>