Ajax/Php - Real Time Online User Counter

I want to have an Online user counter but something which performs real time. I mean when someone comes in, the counter updates, or when someone leaves the site, the counter decrease.

I can't find anything like this on net. Is there any script for this ?

Answers

You could probably keep a list of all sessions in a database and update the "online time" every time someone hits a page. Then check how many sessions were updated in the last x minutes. However, this won't be very real time: depending on the amount of minutes you defined it will be a little bit off.

Even Google Analytics (the new real time version) gets it wrong sometimes. Don't worry too much if you can't get it right either. ;-)

You should have a look to WebSocket. There is a lot of demos out there, mostly real-time chat application, you could hack something on it :) In my opinion, WebSocket seems a bit overhead in you case (you just want a number, no real two-sides communications) but it's the good way to do "real-time" apps.

Here are some links:

• Socket.IO (node.js backend)
• WebSocket and Socket.IO
• Introduction to Server-Sent Events (another technique)
• phpwebsocket

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