Networking

Stream

A logical flow of frames over a single connection.

In plain terms

HTTP/2 introduced streams to multiplex requests. HTTP/3 made each stream independent at the transport layer (no TCP HOL).

Origin

Multiplexed streams over a single connection appeared in SPDY (2009) and became HTTP/2 in 2015. HTTP/3 (2022) made each stream independent at the transport layer.

Where it shows up in production

HTTP/2 Many parallel requests over one TCP connection — but a TCP loss blocks every stream.
HTTP/3 / QUIC True per-stream loss recovery: a dropped packet only stalls one stream.
gRPC streaming Server-streaming, client-streaming, and bi-directional streaming RPCs all use HTTP/2 streams.

On Semicolony

Simulator http2 streams

Sources & further reading

RFC RFC 9113 §5 — HTTP/2 streams
Docs HTTP/2 streams simulator (Semicolony)

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