WebTransport Application Protocol Negotiation

Category: Network / Connectivity
Type: Chromium catches up
Status: Proposed (Chrome Proposed)
Intent stage: None

Summary

WebTransport Application Protocol Negotiation allows negotiation of the protocol used by the web application within the WebTransport handshake. A web application can specify a list of application protocols offered when constructing a WebTransport object, which are then conveyed to the server via HTTP headers; if the server picks one of those protocols, it can indicate that within response headers, and that reply is available within the WebTransport object.

Standards & signals

Specification: https://w3c.github.io/webtransport/#dom-webtransportoptions-protocols
Firefox: Positive — Firefox has been positive on WebTransport, and Mozilla representatives have been involved in the discussion regarding this flag (and have told me in the past that I don't need to file new standards position for every spec feature).
Safari: Support — Safari has expressed support for WebTransport in general; we've not reached out regarding this individual feature, given that Safari has not shipped WebTransport itself.
Web developers: Positive — IETF MOQ relies on this feature for version negotiation; I've been repeatedly pinged by multiple people there asking when Chrome is going to ship this.
Tracking bug: https://issues.chromium.org/u/1/issues/416080492

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