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Re: Optimizations vs Functionality vs Architecture

From: James M Snell <jasnell@gmail.com>
Date: Tue, 21 Aug 2012 16:24:23 -0700
Message-ID: <CABP7RbdAW6ebpiA08dmp02pgPm9ZLBTPcjHHSkNvJ=D5iUS8-A@mail.gmail.com>
To: Poul-Henning Kamp <phk@phk.freebsd.dk>
Cc: Yoav Nir <ynir@checkpoint.com>, Phillip Hallam-Baker <hallam@gmail.com>, "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
On Tue, Aug 21, 2012 at 2:30 PM, Poul-Henning Kamp <phk@phk.freebsd.dk>wrote:

> In message <2A8028EE-0EEC-4E42-89C4-347C33F60B90@checkpoint.com>, Yoav
> Nir writ
> es:
>
> >A requirement for downgrade creates too many restrictions, even if we
> throw
> > SPDY away. The beginning of a 2.0 connection would have to look enough
> like
> >1.x so as to fool existing servers.
>
> Yes, and ?
>
> Sending:
>
>         HEAD / HTTP/1.1
>         Upgrade: HTTP/2.0
>
> as a preamble on a connection is not very expensive.
>
>
Sending is not a problem... but handling it on the server side could be
depending on what work the server needs to do to generate the HEAD
response. As per the spec, "The metainformation contained in the HTTP
headers in response to a HEAD request SHOULD be identical to the
information sent in response to a GET request" .. calculating the Entity
Tag, Last-Modified Timestamp, Content-Length and Content-Type headers could
be rather more expensive than one may expect depending on what's on the end
of that request.

- James


> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk@FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
>
Received on Tuesday, 21 August 2012 23:25:10 GMT

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