I have been working on an ajax/php chat system where users can obviously chat with one another. Im concerned about server load, the way it was originally programmed was auto refresh div (chat box) every x seconds it only did this is the user was active as i timed out their inactivity. If they remained inactive for 10 minutes or so they would be shown as idle the system would then stop refreshing. Then i looked into Server-Sent Events with HTML5 which worked well however not all browsers work with this.
Does anyone have a better solution or is the div refresh ok for now? Hope someone can help thanks!
Consider using COMET, or take a look at Ajax Push Engine: Link
An example of a chat system using COMET: Link