HTTP extensions, semantics and HTTP datagrams / MASQUE / WEBTRANS

[Mark Nottingham <[e-mail]>]

Hi all,

The new MASQUE[1] and WEBTRANS[2] working groups both wish to define new protocols using QUIC DATAGRAM frames[3] that are not conveying (existing) HTTP semantics, but are intended to be usable over (at least some versions of) a HTTP connection.

MASQUE's purpose is to proxy UDP and potentially IP (like a VPN) over a HTTP/3 connection. For WEBTRANS, the purpose is to create a browser-exposed, WebSocket-like protocol that allows unreliable delivery (which may also use CONNECT-UDP). These summaries are just my understanding; for a more complete picture, see the respective charters and related WG discussion.

It's not yet clear how or even if these protocols will map into HTTP semantics. Some have proposed something like a CONNECT-UDP method; others seem to favour negotiating a new protocol using SETTINGS or a similar version-specific mechanism directly, avoiding the definition of any generic HTTP semantics.

So far, the most concrete proposal we have is draft-schinazi-quic-h3-datagram,[4] which defines how QUIC DATAGRAM frames are surfaced in HTTP/3 without any mapping them into generic HTTP semantics (like a method, status code, header, etc.). Thus, a specification using them has the choice of defining a generic HTTP extension (like CONNECT-UDP, mapping them into HTTP semantics) or a version-specific extension(like SETTINGS, bypassing generic semantics).

Before these groups get too far down the road, we have an opportunity to give them some guidance about how to extend both HTTP's semantics overall, and specific versions of HTTP -- keeping in mind recent core discussions.[5] 

The most relevant question is whether new, non-HTTP protocols on a HTTP connection should be bootstrapped by generic HTTP semantics (e.g., a method), version-specific semantics (e.g., SETTINGS), or something else. 

There's also a question as to whether something like draft-schinazi-h3-datagram is the right approach, or whether it should also include generic HTTP semantics "bundled in."

Do folks have any thoughts about this? 

Cheers,


1. <https://datatracker.ietf.org/wg/masque/about/>.
2. <https://datatracker.ietf.org/wg/webtrans/about/>.
3. 'An Unreliable Datagram Extension to QUIC', <https://tools.ietf.org/html/draft-ietf-quic-datagram>.
4. <https://tools.ietf.org/html/draft-schinazi-quic-h3-datagram>.
5. <https://github.com/httpwg/http-core/issues/44>.

--
Mark Nottingham   https://www.mnot.net/