Re: Push and Caching

Martin Thomson <martin.thomson@gmail.com> Tue, 26 August 2014 23:24 UTC

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Date: Tue, 26 Aug 2014 16:22:13 -0700
Message-ID: <CABkgnnUXs=0U_m6bX4g=B9w+MnXdixe_Vo=HnCcAp8NgtE7xpA@mail.gmail.com>
From: Martin Thomson <martin.thomson@gmail.com>
To: William Chow <wchow@mobolize.com>
Cc: "Roy T. Fielding" <fielding@gbiv.com>, Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>
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Subject: Re: Push and Caching
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On 26 August 2014 16:07, William Chow <wchow@mobolize.com> wrote:
> What I am hoping we'd be able to do is to include language that describes the relationship between the original request/response and the pushed responses, so that caches have guidance on when it is safe to serve a pushed response when the client-initiated request is actually received later from the UA.

Any association between a request and any server pushes it generates
is largely incidental from the perspective of what we are talking
about right now (caching, validity, general usability).  Each
request-response pair can be considered completely independent in that
regard, in fact, in virtually all respects.  Caches can and should
treat each independently.

The only tricky part is to determine when it is best to push something
when you don't have any cues from the server.  You could, for
instance, remember the set of pushed resources that came in response
to a given request and push those too, or you could build new
heuristics around push for origin servers that don't generate it.
That's something that is up to you.