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Real-time and feeds

Module 12 of the System Design Masterclass. Every lesson here is free to read, with no account.

  • 4 lessons
  • 1 h 40 min of reading
  1. 75Polling, long polling, SSE and WebSocketsFour ways to send news from a server to a phone (polling, long polling, Server-Sent Events and WebSockets), using a live cricket score, and what an open connection costs.23 minCore Fast track
  2. 76A feed for 10 million followers: build early or on demand (fan-out)Two ways to build a home feed (push posts into follower lists, or merge on each read) and the hybrid for accounts with millions of followers.23 minCore Fast track
  3. 77Case study: Chat (WhatsApp)How to design a chat app: connection servers, a store-first message path, order inside each chat, receipts, offline messages and presence, with the numbers.26 minCore · Case study Fast track
  4. 78Case study: News feedHow to design the home feed of a social app: the path of a post and of a feed open, a hybrid timeline, a ranking step that can be switched off, photos on a CDN and the caches, with the numbers.28 minCore · Case study

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