Re: New Version Notification for draft-nottingham-httpbis-retry-01.txt

"Roy T. Fielding" <fielding@gbiv.com> Sat, 04 February 2017 06:07 UTC

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From: "Roy T. Fielding" <fielding@gbiv.com>
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Date: Fri, 3 Feb 2017 22:03:40 -0800
Cc: Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>
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To: Tom Bergan <tombergan@chromium.org>
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Subject: Re: New Version Notification for draft-nottingham-httpbis-retry-01.txt
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> On Feb 1, 2017, at 12:41 PM, Tom Bergan <tombergan@chromium.org> wrote:
> 
> > Applications sometimes want requests to be retried by
> > infrastructure, but can't easily express them in a non-idempotent
> > request (such as GET).
> 
> nit: did you mean "in an idempotent request (such as GET)"?
> 
> > A client SHOULD NOT automatically retry a failed automatic retry.
> 
> Why does RFC 7230 say this? I am aware of HTTP clients that completely ignore this suggestion, and I can't offhand think of a reason why this is a good rule-of-thumb to follow.

This is only referring to retries due to a dropped connection. The reason is because a
second connection drop is (in almost all cases) due to the request itself, as opposed to
something transient on the network path.  [BTW, this doesn't refer to requests yet to be
sent in a request queue or pipeline -- just the retried request in flight for which no response
is received prior to FIN/RST (or equivalent).]

There might be a good reason to go ahead and retry with an exponential back-off,
but I don't know what that would be in general. I know lots of clients do stupid
things because they are afraid of communicating server errors to their user.

....Roy