Скачать или смотреть System Design Interview: How WhatsApp Actually Works | Real-Time Messaging Architecture

Preparing for a system design interview? Learn how to design a massive chat application like WhatsApp from scratch. We'll walk through real-time messaging, group chats, read receipts, and scaling strategies used by engineers at top tech companies.
[What You'll Learn] In this comprehensive system design breakdown, you'll discover:
✅ Interview Strategy – Why to start with core features (1:1 messaging, groups) and how to scope your design within 45-60 minutes
✅ Real-Time Architecture – Moving from HTTP to WebSockets for persistent, bidirectional communication
✅ Microservices Design – Decoupling the Gateway (connection holder) from Sessions Service (message router) to eliminate single points of failure
✅ Message Delivery Flow – Engineering the "Sent," "Delivered," and "Read" tick system with acknowledgments
✅ Presence Indicators – Implementing "Last Seen" and "Online" status using timestamp tracking and activity monitoring
✅ Group Chat Scaling – Handling group messages efficiently with consistent hashing and fan-out optimization strategies
[Key Technical Concepts] • Load Balancing & Gateway Architecture • Long Polling vs WebSockets comparison • Session management and connection mapping • Message Queues for reliability and async processing • Thrift Protocols & deprioritization during peak loads • Consistent Hashing for distributed group management • Memory optimization through Parser/Unparser services
[Perfect For]
Software engineers preparing for FAANG interviews
Backend developers learning distributed systems
Students studying real-world system architecture
Anyone curious about how WhatsApp handles billions of messages daily
[Chapters] 0:00 - Introduction & Scope Definition 2:15 - High-Level Architecture Overview 5:30 - Sessions Service: Decoupling Connection Logic 8:45 - HTTP vs WebSockets: Choosing the Right Protocol 12:20 - Message Delivery: The "Ticks" System Explained 16:10 - Last Seen Feature Design 19:40 - Group Messaging at Scale 24:05 - Optimization: Parser Service & Memory Management 27:30 - Handling Peak Traffic & Deprioritization 30:00 - Final Architecture Review & Interview Tips
[Resources & Related Videos] 🔗 Load Balancers Deep Dive: [Link] 🔗 Message Queues Explained: [Link] 🔗 System Design Playlist: [Link]
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