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Re: Query string cacheability

From: Henrik Nordström <henrik@henriknordstrom.net>
Date: Thu, 20 May 2010 11:56:09 +0200
To: HTTP Working Group <ietf-http-wg@w3.org>
Message-ID: <1274349369.902.34.camel@henriknordstrom.net>
ons 2010-05-19 klockan 15:09 -0700 skrev Roy T. Fielding:
> I would prefer to remove the paragraph from the spec.  It was not true when
> it was added, it isn't true now, and it won't be true tomorrow.

Partly agreed.

I think it would be quite unexpected for a shared cache to enforce
caching of such URLs by a expiry time set in the cache.

I technically see no problem with using the general heuristics
calculations based on Last-Modified. If a query response includes
Last-Modified time then it should be safe to cache.

The tricky query responses is those having neither an explicit expiry
time or Last-Modified and there you can find both old and new web
applications not expecting the response to get cached. But I do not have
any data on how common such applications are, nor do I have data on how
common it is to administratively configure caches to heuristically
assign a freshness interval to responses without Last-Modified.

But I also do think that practically nothing will break if this rule is
removed from the specifications, and the HTTP world will adjust with
little or no fuzz about it. The requirements on servers to clearly
indicate when responses are not intended to be cached has been around
for quite some time now, even long before the text in question was

As Squid has already been mentioned I can note that current Squid
implementation implements this 2616 rule purely in the recommended
configuration of heuristic cache rules. The code as such do not make any
distinction for query URLs.

Received on Thursday, 20 May 2010 09:56:42 UTC

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