Design62 min
Pushing updates to clients the moment they happen.Merging concurrent edits so every copy converges to the same state.Persistent two-way connection between browser and server.Core featuresFull-duplex over one TCP connectionServer push, no pollingLow per-message overheadStateful: sticky, harder to load-balanceWhen to useChat, live collaboration, multiplayerLive feeds, presence, notificationsServer must push without being askedKeeping data correct when many requests touch it at once.Splitting data across machines so no single node holds it all.
PremiumCollaborative Whiteboard / Miro
An endless canvas that whole teams scribble on together: sticky notes, shapes, arrows and pen strokes appear on every screen as they're made, and a board that has grown for years still opens in a second.
What they’re really testing: Hundreds of people can be moving, typing and drawing on one board at once, and every screen has to agree on the result within a blink. Boards grow to hundreds of thousands of things on a canvas with no edges, too many for any laptop or phone to hold, yet everyone must see the same board.
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What’s inside
- Primary concepts and the hard part
- Requirements
- API / Model
- High-level architecture
- Trade-offs and deep dives
- Possible follow-up questions