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Re: Expect: + Upgrade: = ...

From: Daniel Stenberg <daniel@haxx.se>
Date: Wed, 4 Sep 2013 23:29:19 +0200 (CEST)
To: Martin Thomson <martin.thomson@gmail.com>
cc: HTTP Working Group <ietf-http-wg@w3.org>
Message-ID: <alpine.DEB.2.00.1309042317580.7714@tvnag.unkk.fr>
On Wed, 4 Sep 2013, Martin Thomson wrote:

>> The effect seems to risk a little more data waste in the HTTP+upgrade case.
> Yeah, I'm thinking that for https: URLs it's easy.  ALPN means that there is 
> no probing.  And you get the option to use flow control.  In fact, that's 
> actually much nicer.

Yes I agree that the https method of deciding protocol is nicer and less 
problematic. But I forsee a future where people will use the same operations 
like today but only enable http2, and then the URL will remain as-is which 
often means http://.

> For http: URLs, it's a little trickier.  You might do a HEAD request for the 
> upgrade request, followed by a POST after the upgrade completes.  That's 
> round trips still, and if the upgrade fails, it's even worse.  Though, I'll 
> note that it's still the same speed in the success case as the https: URL 
> case ...

I've already been burned in the past trying to do HEAD when a POST is asked 
for. There are unfortunately too many servers out there that accept POST but 
refuse HEAD for the same URI so it isn't a way I would like to go either...

But again, I don't think this is a big problem.


  / daniel.haxx.se
Received on Wednesday, 4 September 2013 21:29:53 UTC

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