WebTransport: как это работает на практике

Question

Accepted Answer

WebTransport работает поверх **HTTP/3 CONNECT** — multiplexes с обычным h3 traffic на том же UDP port, без отдельного connection как у WebSocket.

## Разбор

Два примитива:

- **Streams** — reliable, ordered *within stream*, independent *across* streams. `ReadableStream`/`WritableStream`, native backpressure. Chat, file chunks, RPC.
- **Datagrams** — `connection.datagrams`, unreliable, unordered. Dropped = gone, no retransmit, no HOL blocking. Player positions, cursors, telemetry — freshest value obsoletes last.

QUIC inheritance: **0-RTT/1-RTT setup** и **connection migration** (Wi-Fi→cellular без full re-handshake) — meaningful для mobile.

## Итог

WebTransport = HTTP/3 session с streams (reliable) и datagrams (unreliable); QUIC даёт fast setup и migration — transport, не framework.