I know that Playfab is on RESTful API and stateless service. This give me problem as I can not tell if a friend is online or offline. How can I tackle this problem? I want keep checking after interval if the player is still online or not. I think I'll need to store status as player data or statistics and send some command using cloud computing in intervals to check if the guy is still online (changing the status to online when one logs in and set him to offline if the cloud computing fails) but I'm not sure. Can you guide me? It would be really helpful.