Re: Unbound DATA frames in HTTP/3 proposal

Hi,

Thanks for the proposal. While the use case(s) might seem niche, I think there are enough avenues that could benefit from such an extension.

HTTP/3 framing, while powerful, is a common impediment to more optimized data paths that HTTP/1.1 can leverage. 

The use cases described such as CONNECT streams are "odd" in HTTP terms anyway and already don't allow for things like trailers. This extension spells that existing reality in a different way.

In some ways, this reminds me of proxy protocol v2 [1]. A binary format for header containing some useful info, before switching into full byte streaming mode.

Cheers
Lucas

[1] https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt

On Fri, Oct 3, 2025, at 21:42, Yaroslav Rosomakho wrote:
> Dear HTTP Working Group,
> 
> While HTTP/3 streams are very efficient for long-term connections such as CONNECT, WebSockets and WebTransport, the requirement to encapsulate everything into finite-length DATA frames reduces potential performance and flexibility. Best case scenario it introduces few extra unnecessary bytes on the wire, worst case scenario it can cause an extra memory copy.
> 
> David and I would like to propose an optional extension, UNBOUND_DATA frame. This frame indicates that the remainder of the stream is data. This reduces framing overhead and simplifies transmission of long-lived or indeterminate-length payloads.
> 
> Feedback and suggestions are very welcome.
> 
> Best Regards,
> Yaroslav
> 
> ---------- Forwarded message ---------
> A new version of Internet-Draft draft-rosomakho-httpbis-h3-unbound-data-00.txt
> has been successfully submitted by Yaroslav Rosomakho and posted to the
> IETF repository.
> 
> Name:     draft-rosomakho-httpbis-h3-unbound-data
> Revision: 00
> Title:    Unbound DATA Frames in HTTP/3
> Date:     2025-10-03
> Group:    Individual Submission
> Pages:    8
> URL:      https://www.ietf.org/archive/id/draft-rosomakho-httpbis-h3-unbound-data-00.txt
> Status:   https://datatracker.ietf.org/doc/draft-rosomakho-httpbis-h3-unbound-data/
> HTML:     https://www.ietf.org/archive/id/draft-rosomakho-httpbis-h3-unbound-data-00.html
> HTMLized: https://datatracker.ietf.org/doc/html/draft-rosomakho-httpbis-h3-unbound-data
> 
> 
> Abstract:
> 
>    This document defines a new HTTP/3 frame type, UNBOUND_DATA, and a
>    corresponding SETTINGS parameter that enables endpoints to negotiate
>    its use.  When an endpoint sends an UNBOUND_DATA frame on a request
>    or response stream, it indicates that all subsequent octets on that
>    stream are interpreted as data.  This applies both to message body
>    data and to octets transmitted after CONNECT or extended CONNECT.
>    The use of UNBOUND_DATA removes the need to encapsulate each portion
>    of the data in DATA frames, reducing framing overhead and simplifying
>    transmission of long-lived or indeterminate-length payloads.
> 
> 
> 
> The IETF Secretariat
> 
> 
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