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Re: #385: HTTP2 Upgrade / Negotiation

From: Mark Nottingham <mnot@mnot.net>
Date: Tue, 23 Oct 2012 13:50:46 +1100
Cc: "ietf-http-wg@w3.org Group" <ietf-http-wg@w3.org>
Message-Id: <D50A6AF2-356F-4BDF-9DCF-3916F8AA2345@mnot.net>
To: William Chan (陈智昌) <willchan@chromium.org>

On 23/10/2012, at 1:33 PM, William Chan (陈智昌) <willchan@chromium.org> wrote:

> Overall, sounds good. I've included some clarifications/questions below.

[...]

>> Who's willing to do some experimentation? Specifically, does anyone have access to the code that was used before (IIRC, people bought some ads and inserted some Java to probe the network)?
> 
> Do you mean the Chromium HTTP upgrade experiment agl referred to in
> http://www.ietf.org/mail-archive/web/tls/current/msg05593.html?

No, IIRC there was also some broader experimentation using ads; I'll dig around a bit more. 

Of course, if Chrome (or any other browser) would be interested in running an experiment, we'd love to do that too -- provided we can have input into the design.


>> Does anyone object to us defining such a record (type TBD), as long as it's not the only way to get to HTTP/2 for HTTP URIs?
> 
> I'm not sure if my previous emails were taken to indicate "interest"
> here. I forget what I said too :) As long as this is more of an
> optional optimization than anything, I guess I'm OK with it. I'm very
> much concerned about relying on it, due to experiments we have run
> with TXT records that show us noticeably higher failure rates in
> comparison to port 443, higher latency (we'd definitely have to race
> this), and extra DNS queries.

Yes, I think relying on it would be a mistake, for a variety of reasons.


>> 2) Using a response header to hint that HTTP/2 is available on another port.
>> 
>> This approach hasn't been talked about in detail yet, but it apparently (as some have noted) has the disadvantage of not upgrading the first interaction, and of requiring a separate cache (and caching model) for this information.
> 
> Just to be clear, SRV records also have the disadvantage of not
> upgrading the first interaction, unless you block on the response,
> which Chromium definitely is not going to do unless the environment
> changes such that it doesn't kill performance.


I'll leave it to the DNS experts to debate the capabilities and merits here.


--
Mark Nottingham   http://www.mnot.net/
Received on Tuesday, 23 October 2012 02:51:04 GMT

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