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Re: Header compression: header set diff

From: Roberto Peon <grmocg@gmail.com>
Date: Thu, 21 Mar 2013 16:47:08 -0400
Message-ID: <CAP+FsNcHTJRsuZ9ZAH6FdQnQjBSpJ08brYnbNhnSM0e5_ZjLAA@mail.gmail.com>
To: James M Snell <jasnell@gmail.com>
Cc: Patrick McManus <pmcmanus@mozilla.com>, HTTP Working Group <ietf-http-wg@w3.org>, RUELLAN Herve <Herve.Ruellan@crf.canon.fr>
Unless, of course, you ever intend to do server push :)

On Thu, Mar 21, 2013 at 3:53 PM, James M Snell <jasnell@gmail.com> wrote:

> +1.. In addition to this,  response headers tend to be significantly more
> variable than request headers...  Which,  of course means much lower
> compression ratios anyway if we're talking about delta based mechanisms.
> It makes very little sense to optimize for the response side.
> On Mar 21, 2013 6:14 AM, "Patrick McManus" <pmcmanus@mozilla.com> wrote:
>> On Thu, Mar 21, 2013 at 8:50 AM, RUELLAN Herve
>> <Herve.Ruellan@crf.canon.fr> wrote:
>> > To better understand the impact of this choice of persisting the header
>> set, we tested it inside HeaderDiff and saw a slight improvement of
>> compaction for requests but also a slight(er) decrease of compaction for
>> responses.
>> All else being equal (which is of course never true), compression
>> ratio of requests is more important than responses because the MUX
>> allows multiple requests to fit inside the cwnd (and thus avoid
>> scaling by rtt). The better the ratio, the greater the number of
>> transactions in 1-flight-mux. On the response side the headers are
>> mixed in with data frames which in many (but not all) scenarios
>> overhwelm the headers on a byte count basis - so the effect of header
>> compression is less likely to impact congestion control.
Received on Thursday, 21 March 2013 20:47:35 UTC

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