How to implement a realtime notification system on the site?

Question

PHP

Hello!

What is the best/correct way to implement a real-time notification system on a website? That is, notifications, for example, at the time of receiving a message, etc. (like VK).

In such cases, they usually keep 1 open socket connection constantly, or what?

Answer 1

socket.io is great. Look. There is documentation

Answer 2

nodejs+https: //www.npmjs.com/package/websocket

Answer 3

I understand when you can't find anything. But damn it, is it difficult to enter Yandex? there are already ready-made implementations.
Tyk
Request
Better of course to raise nodejs and websocket.