Subject: Alt-Svc NOT_AUTHORITATIVE proposal

From: Martin Thomson <[email-masked]>
Date: Tue, 25 Feb 2014 13:33:15 -0800

Alt-Svc defines an HTTP/2 error code, presumably for RST_STREAM to
signal to a client that it does not believe that it is authoritative
for the resource identified in a request.

I think that this concept is a powerful one, but it doesn't belong in
HTTP/2.  This should be a new HTTP status code.

Superficially at least it seems to be a 4xx series status code,
similar in function to 404, but also very different.

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From: Patrick McManus <[email-masked]>
Date: Wed, 26 Feb 2014 08:22:18 -0500

Martin - that makes sense to me. Next time we update the draft we can
rewrite the http/2 stream error code as a 4xx HTTP/* status code.

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From: Mark Nottingham <[email-masked]>
Date: Thu, 27 Feb 2014 12:27:29 +1100

WFM too.

BTW, I’ve started collecting issues against the draft here:
  https://github.com/mnot/I-D/issues?labels=alt-svc&page=1&state=open

Cheers,

On 27 Feb 2014, at 12:22 am, Patrick McManus <[email-masked]> wrote:

> Martin - that makes sense to me. Next time we update the draft we can rewrite the http/2 stream error code as a 4xx HTTP/* status code. 

--
Mark Nottingham   http://www.mnot.net/

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From: William Chan (陈智昌) <[email-masked]>
Date: Wed, 26 Feb 2014 19:54:22 -0800

Hm, superficially it seems pretty similar to 404 to me as well. I guess a
different status code might help in debugging though.

On Wed, Feb 26, 2014 at 5:27 PM, Mark Nottingham <[email-masked]> wrote:

> WFM too.
>
> BTW, I've started collecting issues against the draft here:

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From: Ryan Hamilton <[email-masked]>
Date: Wed, 26 Feb 2014 20:36:32 -0800

Is the expectation that when a client sees such an error/status code that
it should retry the request on a non-alternate service?

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From: Patrick McManus <[email-masked]>
Date: Thu, 27 Feb 2014 13:10:02 +0000

> it should retry the request on a non-alternate service?
yes - or a different alt service if we're doing lists.. i.e. your route
needs fixing

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From: Patrick McManus <[email-masked]>
Date: Thu, 27 Feb 2014 13:09:55 +0000

404 means "I know that this URI can't be found".. its a terminating
condition and a definitive response.

4xx not_authoritative means "I don't have this URI.. maybe (or maybe not)
some other host does"
.. it might not be a terminating condition if you have other routes..

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From: Martin Thomson <[email-masked]>
Date: Thu, 27 Feb 2014 09:03:10 -0800

> .. it might not be a terminating condition if you have other routes..

You might also consider it analogous to a redirect with no actual
directions included.  But again, that's not right either.  It's
definitely a new code.

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From: Mark Baker <[email-masked]>
Date: Thu, 27 Feb 2014 12:06:46 -0500

> .. it might not be a terminating condition if you have other routes..

I haven't been paying close attention, but are you guys talking about
a 203 response?

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From: Martin Thomson <[email-masked]>
Date: Thu, 27 Feb 2014 09:57:10 -0800

> I haven't been paying close attention, but are you guys talking about

A 203 says that you have *an* answer, but that it might not be
genuine.  We're talking about the case where you asking the wrong
server.

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From: Mark Baker <[email-masked]>
Date: Thu, 27 Feb 2014 13:18:57 -0500

> genuine.  We're talking about the case where you asking the wrong

Ah, I see, thanks. Seems like 404 would cover this perfectly then, as
there's no such thing as a "wrong server" (as all HTTP servers can
accept requests for all URI), just a server that can't provide any
representations of the identified resource.

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From: Martin Thomson <[email-masked]>
Date: Thu, 27 Feb 2014 10:32:26 -0800

> representations of the identified resource.

All HTTP servers might be able to accept requests for all URIs, but
they aren't necessarily authoritative for them.  We want to avoid the
case where clients get confused by a response that says a resource
doesn't exist, where it might...were they to ask the right server.

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From: William Chan (陈智昌) <[email-masked]>
Date: Thu, 27 Feb 2014 10:39:02 -0800

Such a new status code might provide a good signal for negatively updating
the Alt-Svc cache a user-agent is probably maintaining.