How to interpret the oauth expires=4 digit code upon receiving access token

Question

In my application, certain clicks need to generate facebook post. I popup the facebook login screen if I have no access token.

Upon receiving the access token I also receive a "expires=4 digit number" at the end.

e.g. expires=3994

What does that 4 digit code mean?

Is it time in seconds after which the access token will expire?

Or is it the number of ticks after which the access token will expire.

I have seen some facebook api code which expects 12 digit expires code but I am receiving only 4 digits.

The reason I need to know if the access token has expired is that I do not want my post to fail and would like to pop up the login screen if it has expired.

Answer 1

It is the no of seconds before expiry time. i.e.

3994 / 60 / 60 =~ 1 hour

If you see more digits (especially on canvas access link), it is probably a Unix time-stamp which you can convert to seconds easily. Also you can use below scope to get a non expiring token (but it will display an additional warning with the authorization popup window):

scope=offline_access

At my project (http://www.nbusy.com/projects/communicator) I use something like the below to know of the token expiry time:

DateTime eprityTime = DateTime.Now.AddSeconds(3994);

and compare it with DateTime.Now and close the session when token expires.