I am currently creating an application using Java/Groovy that allows a user to login using Facebook, this works perfectly and when they successfully login I can see on the Facebook analytics who's on my web app.
Is there a way to find out all the users who are logged in to my application via the API? I am currently using restfb. I want to find all my users, check their locations and then display the ones closest to the user.
I can't seem to find any documentation on this on the Facebook developer site
There is no way to do this with the API anymore, you will have to implement that functionality on your own.