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Re: Header Table and Static Table Indicies Switched

From: Jeff Pinner <jpinner@twitter.com>
Date: Fri, 1 Aug 2014 15:59:22 -0700
Message-ID: <CA+pLO_hF-Rsct3qQEbRWBwYBm=BJ5NF+D2mwqty3fgFR8NEJEg@mail.gmail.com>
To: Greg Wilkins <gregw@intalio.com>
Cc: Jason Greene <jason.greene@redhat.com>, HTTP Working Group <ietf-http-wg@w3.org>
Greg,

I run a reverse proxy that handles things like authentication,
rate-limiting, etc. for the backend servers I talk to.

This means lots of custom headers that annotate requests with that information.

There are also lots of public APIs that use custom headers and these
have to all be proxied using names not in the header table. Here's a
google example:

https://developers.google.com/youtube/2.0/developers_guide_protocol_resumable_uploads

So the TL;DR is that in browser use cases, yes most of the headers
sent will be in the static table. But for APIs, internal requests,
etc. the majority of headers will not be :(

- Jeff

On Fri, Aug 1, 2014 at 3:39 PM, Greg Wilkins <gregw@intalio.com> wrote:
>
> On 2 August 2014 03:37, Jeff Pinner <jpinner@twitter.com> wrote:
>>
>> Must have missed the connection between removing the "reference set"
>> and switching the table order.
>>
>> I am happy to show data on how it is worse, specifically encoding
>> header names indices is now 200% worse ;)
>
>
>
> Jeff,
>
> I used the test data set and used header table sizes from 0 to 16KB.
>
> There are 126 indexes that can be sent as a single byte, so the 61 static
> entries take only half of those.   You have to have more than 65 indexed
> headers before any two byte name indexes will be used.... and then it still
> has to be a name that has not been used for one of those 65 custom entries.
>
> Sure you can craft a data set that does end up using a lot of 2 byte name
> indexes, but I'd be amazed if it was from anything approaching normal
> traffic.
>
> If there are are larger normal traffic data sets available, then I'm happy
> to run the numbers again.
>
> cheers
>
>
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>
> --
> Greg Wilkins <gregw@intalio.com>
> http://eclipse.org/jetty HTTP, SPDY, Websocket server and client that scales
> http://www.webtide.com  advice and support for jetty and cometd.
Received on Friday, 1 August 2014 22:59:49 UTC

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