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Re: draft-ietf-httpbis-alt-svc-12.txt

From: Martin Thomson <martin.thomson@gmail.com>
Date: Sat, 27 Feb 2016 07:42:33 +1100
Message-ID: <CABkgnnVC9mJxKS9DM42UOiUJ9CfeeVgLJikoybwR5bEXsUZBmA@mail.gmail.com>
To: Kari Hurtta <hurtta-ietf@elmme-mailer.org>
Cc: Mark Nottingham <mnot@mnot.net>, Julian Reschke <julian.reschke@gmx.de>, HTTP WG <ietf-http-wg@w3.org>, Mike Bishop <Michael.Bishop@microsoft.com>, Patrick McManus <mcmanus@ducksong.com>
We should be clear, 3.4 (prior knowledge) is exceptional and doesn't apply
here.  That same prior knowledge could be used to find an alternative.
On Feb 26, 2016 6:18 PM, "Kari Hurtta" <hurtta-ietf@elmme-mailer.org> wrote:

> Julian Reschke <julian.reschke@gmx.de>: (Thu Feb 25 15:18:55 2016)
> > On 2016-02-10 22:31, Mike Bishop wrote:
> >> I agree.  For example, if the proposal of using a .well-known URI to
> delegate to an Alt-Svc gets traction and becomes an RFC, it could just
> update Alt-Svc to define that as having assurance as well.
> >>
> >> Note that h2c on the same port doesn't need Alt-Svc, since the Upgrade:
> header from the server is already defined.  So what we're really talking
> about is h2c *on a different port*.  Honestly, I think if we put it on a
> different port and publish an Alt-Svc pointing to it, we might as well go
> direct (i.e. don't Upgrade from HTTP/1.1 on the new connection), which
> would need a new token anyway.
> >
> > "new token" in what sense?
> >
> > Best regards, Julian
>
>
> Hypertext Transfer Protocol Version 2 (HTTP/2)
> RFC 7540
>
> 3.1.  HTTP/2 Version Identification
> https://tools.ietf.org/html/rfc7540#section-3.1
>
> |   o  The string "h2c" identifies the protocol where HTTP/2 is run over
> |      cleartext TCP.  This identifier is used in the HTTP/1.1 Upgrade
> |      header field and in any place where HTTP/2 over TCP is identified.
> |
> |      The "h2c" string is reserved from the ALPN identifier space but
> |      describes a protocol that does not use TLS.
>
>
> Is "h2c" reserved for clear text HTTP/2 with Upgrade: -header negotiation ?
>
> If there is "h2c" on Alt-Svc it can mean either clear text HTTP/2
> with Upgrade -negation or clear text HTTP/2 with Prior Knowledge
> but it can not mean both.
>
> 3.4.  Starting HTTP/2 with Prior Knowledge
> https://tools.ietf.org/html/rfc7540#section-3.4
>
> |   A client can learn that a particular server supports HTTP/2 by other
> |   means.  For example, [ALT-SVC] describes a mechanism for advertising
> |   this capability.
>
> So it is unclear that is Upgrade: -supposed to be run when
> Alt-Svc -header gives "h2c". But clear text HTTP/2 usage with
> Alt-Svc -header needs own RFC anyway (and nobody supports clear
> text HTTP/2).
>
> / Kari Hurtta
>
>
>
Received on Friday, 26 February 2016 20:43:02 UTC

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