Re: Alt-Svc alternative cache invalidation (ext#16)

Mark Nottingham <mnot@mnot.net> Tue, 19 August 2014 07:29 UTC

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From: Mark Nottingham <mnot@mnot.net>
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Date: Tue, 19 Aug 2014 17:24:53 +1000
Cc: Erik Nygren <erik@nygren.org>, HTTP Working Group <ietf-http-wg@w3.org>
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Subject: Re: Alt-Svc alternative cache invalidation (ext#16)
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On 19 Aug 2014, at 3:42 am, Martin Thomson <martin.thomson@gmail.com> wrote:

> On 18 August 2014 10:37, Erik Nygren <erik@nygren.org> wrote:
>> Would it make more sense for (origin) to be the key with a set of (service
>> protocol, service endpoint) tuples being the value?  This allows a reset or
>> correction (or removal?) by publishing a new set of [(service protcol,
>> service endpoint), ...] values.
> 
> The problem is that there are two different ways to update the set:
> 
> * The Alt-Svc header field bears multiple values and could be used in
> the fashion you describe.
> 
> * The ALTSVC frame type bears just a single value.
> 
> The latter is the problem here.

Yeah. We don't have a concept of replacement at all in the current spec. The header *could* have this semantic, but like Martin points out, the frame would be incapable of doing that (unless we had a 'clear cache for this origin' flag or something simliar).

Cheers,


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