Design31 min
Pushing updates to clients the moment they happen.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.Repeating a request has the same effect as doing it once.Authentication, authorization and protecting data from abuse.Cheap, durable storage for files and blobs, like S3.Core featuresExtreme durability (11 nines)Virtually unlimited scaleLow cost per GB, storage tiersPresigned URLs for direct uploadsWhole-object writes, no in-place editsWhen to useUser uploads, media and backupsLarge files rather than queryable recordsData lakes and long-term archives
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Text in, a cloned or library voice streamed back within a few hundred milliseconds, for millions of developers, billed per character.
What they’re really testing: Every request needs a GPU, and the listener hears every millisecond spent waiting for one. How do you start audio in a few hundred milliseconds, in any of millions of voices, keep a costly fleet busy, and charge exactly once?
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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