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Re: Fragmentation for headers: why jumbo != continuation.

From: Greg Wilkins <gregw@intalio.com>
Date: Fri, 11 Jul 2014 15:50:37 +1000
Message-ID: <CAH_y2NHohfrZS8ou4yPmHX8WWBA5a+aaT2aPbeCKzuw3qXWLvw@mail.gmail.com>
To: Mark Nottingham <mnot@mnot.net>
Cc: Willy Tarreau <w@1wt.eu>, Roberto Peon <grmocg@gmail.com>, HTTP Working Group <ietf-http-wg@w3.org>
On 11 July 2014 15:32, Mark Nottingham <mnot@mnot.net> wrote:

> Roberto isn't making a latency argument -- it's an argument for minimal
> buffering in the optimistic case(s).



Servers have to hold the headers for the entire request handling duration
anyway (unless you throw away all the general purpose servers that we
currently have), so it makes no difference to their buffering if the
headers arrive in 1 or many fragments.

Proxies cannot forward headers in fragments because:

   1. the routing information may be in the last fragment.
   2. because encoding mutates the ref set, a proxy cannot commence sending
   headers until it has all fragments, else it risks blocking the whole
   connection.

Getting rid of the ReferenceSet may fix 2 and help with 1 in special
cases.

But I maintain that if we really want to fragment headers, then put them in
a segment of DATA frames rather than invent a second mechanism.
cheers

-- 
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, 11 July 2014 05:51:08 UTC

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