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Re: Alternative Header Compression Update..

From: James M Snell <jasnell@gmail.com>
Date: Wed, 10 Jul 2013 11:31:00 -0700
Message-ID: <CABP7RbfTipnrmw4f38S9eYB-gLyS7W=0TwzBaW+7zx46H04EXQ@mail.gmail.com>
To: Mike Bishop <Michael.Bishop@microsoft.com>
Cc: "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
On Wed, Jul 10, 2013 at 11:22 AM, Mike Bishop
<Michael.Bishop@microsoft.com> wrote:
> One advantage of removing the reference set is that Gabor's streaming proposal can be taken even further -- HEADERS frames from different streams can be interleaved with other frame types, because the headers they add to a stream are emitted as the frame is processed and the header table is always in a consistent state.
>

Yes... streaming encoding is possible in my stored header encoding
approach as well. It definitely makes for a much nicer approach, IMHO.

> Whether this would be desirable or useful, however, seems unclear.  HEADERS frames must still be processed in order for compression views to be consistent, and for HTTP semantics must precede any DATA on the same stream.
>

Well, if nothing else, it simplifies the encoding and decoding process
and makes it significantly easier to achieve O(1) performance for most
of the operations.

> Typo in your doc, bottom of p.3:  Indexed and Indexed Literal have the same prefix code.  Per 3.5, Indexed Literal should be 11.
>

Thx.. will be fixed in the next iteration :-)

> -----Original Message-----
> From: James M Snell [mailto:jasnell@gmail.com]
> Sent: Tuesday, July 9, 2013 5:40 PM
> To: ietf-http-wg@w3.org
> Subject: Alternative Header Compression Update..
>
> All,
>
> Even tho we decided at the face-to-face to move forward with the header compression draft as the starting point with header compression in http/2 for the implementation draft, I definitely remain skeptical of the overall design of the scheme. I have voiced my reservations in the past and after implementing the current header compression scheme, my reservations about it's design remain.
>
> Combining elements of my previous explorations here with ideas from the current header compression draft, I have posted another update to the "Stored Header Encoding" draft.
>
>   http://www.ietf.org/id/draft-snell-httpbis-bohe-11.txt
>
> This details an alternative scheme that ditches the differential encoding and the reference set, uses a fixed range of header table indices (0x00-FF), and uses a least-recently-written eviction strategy without renumbering. This approach is significantly less complicated to implement at the cost of only a small handful of additional bytes on the wire.
>
> - James
>
>
>
Received on Wednesday, 10 July 2013 18:31:47 UTC

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