HardAI Evaluated

Design a Real-time Chat System

Overview

Design a globally distributed chat platform supporting 1-on-1 chats, large group chats, online status presence, message delivery receipts, and end-to-end encryption.

Requirements

1Real-time 1-on-1 and group messaging with low delivery latency (<100ms)
2Message delivery acknowledgments: Sent, Delivered, Read receipts
3Online presence indicator and push notifications for offline users
4Persistent chat history storage with fast chronological retrieval
5Handle 500M daily active users sending billions of messages

Architecture Hints (4)

Target Concepts

#WebSockets#PubSub#Cassandra#Push Notifications#Presence

Canvas Editor

Design a Real-time Chat System

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