title: Facebook PHP SDK - maintaining a session
body: <p>I've been playing around with the Facebook PHP SDK for a site that I'd like to use Facebook's single sign in for. I've been able to login to my Facebook account from my site and successfully tested a few of the features (posting to /me, an FQL query etc.).</p>
  
  <p>When generating the login URL I have set the cookie parameter to true, however I seem unable to establish a persistent session with Facebook. At the moment the Facebook login window redirects the whole website (I have not yet tested this within the webpage or a popup). The user can authorise and is returned to my site, but the session data is stored in a query string on the return URL. If this string is removed the user must reauthenticate.</p>
  
  <p>Previously I have worked with the JS SDK and this has not been an issue. It's worth noting in this case that I am avoiding using the FBJS (because I believe the PHP SDK is an alternative) and FBML (because it is deprecated) - I also have not implemented a cross domain communication file as this appears to be unnecessary.</p>
  
  <p>I have read about conducting the authentication within an iFrame. I'm unable to find any documentation about this though.</p>
  
  <p>I have considered storing the $_GET querystring in a session on my site and appending it to the website URL, or an iFrame URL, when I need to authenticate. I'm certain that this is the incorrect way to achieve what I'd like though.</p>
  
  <p>Please could someone point me in the direction of some documentation regarding this. Perhaps I am mistaken in thinking I can do this without JS, or maybe I need to manually set up the session cookie? I've searched at length but have been unable to find any documentation that describes this specifically.</p>
  
  <p>Thanks for any help!</p>