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Re: Our old friends, weak ETags

From: Eric J. Bowman <eric@bisonsystems.net>
Date: Tue, 24 Jul 2012 00:39:40 -0600
To: "Adrien W. de Croy" <adrien@qbik.com>
Cc: "Mark Nottingham" <mnot@mnot.net>, "HTTP Working Group" <ietf-http-wg@w3.org>
Message-Id: <20120724003940.19cd850b.eric@bisonsystems.net>
"Adrien W. de Croy" wrote:
> a) does anyone actually use them?


> b) do they work?

I've never heard that they don't, nor run into any problems using them.

> c) do we still need them?

Yes, otherwise I have to cache-expire for all changes to resource state,
without the option to declare certain changes insignificant.  Take a
"weblog entry" resource which includes a # of comments counter, with a
link to a comment thread.  XHR is used to synch the count, eventually.

I only change the Etag if the entry itself is edited.  Since metadata
about the entry may change in the meantime, which isn't significant
enough to warrant a new Etag in my caching scheme, I preface with W/ to
indicate variance from the origin server not requiring cache expiration,
i.e. semantic equivalence.

Received on Tuesday, 24 July 2012 06:40:33 UTC

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