Re: [External⚠️] Re: Unbound DATA frames in HTTP/3 proposal

I think there's an important distinction here between an optional
capability that endpoints can negotiate for potential performance
improvements and what’s defined as part of the base protocol. The earlier
"zero-length DATA means unbounded" proposal would have changed the core
framing semantics for all HTTP/3 traffic; in contrast, UNBOUND_DATA is a
negotiated extension that endpoints can explicitly opt into.

While a dedicated CAPSULE frame type could indeed simplify capsule-based
protocols, the motivation for UNBOUND_DATA goes beyond Capsules. The
immediate driver for me is the standard CONNECT method where the data is
already opaque, and the additional HTTP/3 DATA framing layer introduces
unnecessary per-frame overhead and can, in some implementations, trigger an
extra memory copy.

The goal here is not to change generic HTTP semantics, but to provide an
optional optimisation for cases where framing boundaries have no semantic
value. It can also be used unidirectionally: an endpoint can advertise
support for receiving unbound data without ever sending it itself.

Best Regards,
Yaroslav

On Tue, Oct 7, 2025 at 2:00 AM Kazuho Oku <kazuhooku@gmail.com> wrote:

>
>
> 2025年10月5日(日) 12:48 Mike Bishop <mbishop@evequefou.be>:
>
>> It's been a while and I didn't recall details, so I did a bit of
>> spelunking for the history. There was a proposal
>> <https://github.com/quicwg/base-drafts/pull/2098> to allow DATA frames
>> with length==0 to behave this way, extending to the end of the data stream,
>> for all the reasons you cite.  It was merged, but then Martin observed that
>> all the discussion of it had been on GitHub, rather than the list, so
>> deciding that there had been consensus to merge was improper. We did
>> discuss it on the list
>> <https://mailarchive.ietf.org/arch/msg/quic/3v2fwQJeWO8m7wYazBPxwRDWl88/>,
>> and subsequently reverted it.
>>
>> This isn't an argument for or against your extension, but do page in the
>> history before re-attempting something we decided against previously.
>>
>
> IMO, the arguments against stands today too, for generic HTTP.
>
> At the same time, I share the pain of Yaroslav and David. Because Capsules
> is a TLV format nested on top of HTTP, when using Capsules, we have three
> layers of TLV now, i.e., QUIC STREAM frames, HTTP/3 DATA frames, and
> Capsules.
>
> The complexity does not necessarily come from that they are layered, but
> from the fact that the TLV structures do not share the same boundary. An
> HTTP/3 DATA frame might extend beyond a QUIC STREAM frames and end in the
> middle of the next STREAM frame. Similarly, a Capsule might extend beyond a
> HTTP/3 DATA frame and end in the middle of the next DATA frame.
>
> This disagreement of boundary leads to buffering in each layer,
> speculative or incremental decoding, that are either heavyweight and/or
> complex.
>
> Considering these aspects, I wonder if the middle ground would be to
> specify a HTTP/3 CAPSULE frame that carries one capsule.
>
> It can look like below.
>
> CAPSULE Frame {
>   Type (i) = 0xTBD, // this is HTTP/3 frame type
>   Capsule Type (i), // the type of the capsule
>   Length (i),
>   Data (..),
> }
>
> Admittedly there will be one byte overhead (or one quicint overhead)
> compared to the original proposal, but the benefit is that the design is
> consistent with generic HTTP/3 and therefore would not be a disruptive
> change.
>
> WDYT?
>
>
>> ------------------------------
>> *From:* Yaroslav Rosomakho <yrosomakho@zscaler.com>
>> *Sent:* Friday, October 3, 2025 4:42 PM
>> *To:* ietf-http-wg@w3.org <ietf-http-wg@w3.org>
>> *Cc:* David Schinazi <dschinazi.ietf@gmail.com>
>> *Subject:* Unbound DATA frames in HTTP/3 proposal
>>
>> 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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>
>
> --
> Kazuho Oku
>

-- 


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