Detect if PHP session exists
Facebook now offer subscriptions to users so you can get realtime updates on changes. If my app recieves an update I plan to store it in the database. I would also like to detect if their session exists. If it does then I could update the data in there too.

My session id's are MD5(fb_id + secret) so I could easily edit their session. The question is how can I detect if the session exists.
Detect if PHP session exists
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Facebook now offer subscriptions to users so you can get realtime updates on changes. If my app recieves an update I plan to store it in the database. I would also like to detect if their session exists. If it does then I could update the data in there too.

My session id's are MD5(fb_id + secret) so I could easily edit their session. The question is how can I detect if the session exists.