I have implemented this in a cron job for a contest application to let the existing users know when a new contest has gone online.
More info on this on https://developers.facebook.com/docs/app_notifications/
This is my code:
$facebook = new Facebook(array( 'appId' => FB_APP_ID, 'secret' => FB_APP_SECRET, 'grant_type' => 'client_credentials' )); $post = $facebook->api('/' . $user['uid'] . '/notifications/', 'post', array( 'access_token' => FB_APP_ID.'|'.FB_APP_SECRET, 'href' => getBaseURL(), //this does link to the app's root, don't think this actually works, seems to link to the app's canvas page 'template' => 'Max 180 characters', 'ref' => 'Notification sent '.$dNow->format("Y-m-d G:i:s") //this is for Facebook's insight ));