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Re: Call for Consensus: Remove "reference set" from HPACK (to address #552)

From: Willy Tarreau <w@1wt.eu>
Date: Wed, 16 Jul 2014 07:45:20 +0200
To: Greg Wilkins <gregw@intalio.com>
Cc: Martin Thomson <martin.thomson@gmail.com>, HTTP Working Group <ietf-http-wg@w3.org>
Message-ID: <20140716054520.GC14304@1wt.eu>
On Wed, Jul 16, 2014 at 01:52:35PM +1000, Greg Wilkins wrote:
> Martin,
> 
> static1 was simply switching the indexes so static indexes are 1-61,
> dynamic are 62-.   It was not the proposal to create an extra static bit,
> but is much the same as 7+ allows 126 one byte values, so the first 64
> dynamic entries are 1 byte only.
> 
> No change to the literals. If they use a static name then they index the
> static table as 1-62.  If they are an indexed literal, then a header table
> entry is created and the field will have a field index >61 when next used.

The problem I'm seeing with this change is that you need one extra-byte to
send litteral headers fields that are not present in the static table. Maybe
on the other hand it rarely happens that they're not in the static table ?
It may be nice to re-run a check if we change that to see if the static table
is still optimal then, because before this change, it's only used as a
fallback to look up common values. Now we want it to be used for almost
all litteral lookups, and we might want to add one or two fields there
if we realize that a common one is missing.

I agree however that since we have 7 full bits to send an indexed header,
this will make no change here so that's fine.

Willy
Received on Wednesday, 16 July 2014 05:45:44 UTC

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