Bidirectional server/client communication in JavaScript and PHP

Question

I want to create a multiplayer game using JavaScript (no jQuery) and PHP, where most of the mechanics use AJAX calls. However, I need to determine when a user has left the game to update the player status on other players' screens (I assume by regular AJAX requests?). Also, once all players have left the game files (.txts) on the server need to be deleted.

I am using a free web hosting service which means I can't use WebSockets or cron jobs. I also don't want to use Node.js. Most of what I have read advise regularly timestamping with PHP sessions and this is fine, but I would like to know how to then check to see if the user/game has been inactive for a period of time.

Also, using window.onbeforeunload is too unreliable, in case browsers crash etc.

Answer 1

Don't use the wrong tool for the job.

Any kind of AJAX-based solution you attempt for this purpose is likely to very be inefficient, or unreliable, or probably both. If you have more than a tiny number of concurrent users, the sheer volume of AJAX requests would be likely to overwhelm the server and potentially bust your monthly quota. And as you've discovered, determining when someone has ended their session by closing the browser window is not straightforward or reliable. I would advise against any such architecture.

Websockets is really the correct solution for real-time or near-real-time updates between client and server (and vice versa). It'a also easy for the socket server to know when someone has disconnected (which would occur if they close the window/tab).

So you could either upgrade your hosting so you're able to run a websocket server successfully, or try to integrate a websocket based solution hosted elsewhere, eg Azure SignalR or some similar product (I am not making specific recommendations in an answer, as that's regarded as off-topic).

Answer 2

use an interval function and ping the php endpoint every second. If it stops the User is out