Lesson 12.9

Online presence

Presence servers manage online status and talk to clients over WebSocket.

The rest of this lesson is part of Pro

Pro unlocks every lesson with its animation, code challenge and quiz, plus every interview problem. ₹299 a month or ₹1,999 a year.

Remember it, then prove it

Create a free account to save your progress, get spaced-repetition reviews of what you miss, and design real systems in the interview simulator.