@moq/qmux

A WebTransport polyfill for browsers, using WebSockets as the underlying transport with QMux (draft-ietf-quic-qmux-02, negotiating down to draft-01 and draft-00) framing.

QMux brings QUIC's multiplexed streams and flow control to reliable, ordered byte-stream transports like WebSockets. This allows WebTransport applications to seamlessly fall back when QUIC/UDP is blocked by network middleboxes.

Install

npm install @moq/qmux

Usage

Use as a drop-in WebTransport replacement:

import Session from "@moq/qmux"

const transport = new Session("https://example.com/endpoint")
await transport.ready

const stream = await transport.createBidirectionalStream()

Detecting a dropped session

closed follows the WebTransport contract:

• Fulfills with { closeCode, reason } when the session ends gracefully — a CONNECTION_CLOSE arrived, from either side calling close(). That includes a peer that closes because it caught a protocol violation: it told us why, so you get its close code and reason.
• Rejects when the session ends abnormally, with no CONNECTION_CLOSE: the socket dropped, the peer went idle, or this endpoint caught the peer violating the protocol.

try {
	const info = await transport.closed
	console.log("closed gracefully", info.closeCode, info.reason)
} catch (err) {
	// err is a WebTransportError-shaped SessionError: err.source === "session"
	console.warn("session dropped, reconnecting", err)
}

Don't reach for closeCode to tell the two apart — close codes are application-defined, so an app closing with 1006 is indistinguishable from a dropped socket. The settled state is the signal.

Polyfill

Install as a global WebTransport polyfill:

import { install } from "@moq/qmux"

// Only installs if native WebTransport is unavailable
install()

// Now use the standard WebTransport API
const transport = new WebTransport("https://example.com/endpoint")

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.