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Re: caching HTTP 303 responses

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Tue, 10 Jul 2007 13:45:01 +0100
Message-ID: <46937F4D.4060204@hpl.hp.com>
To: Jacek Kopecky <jacek.kopecky@deri.org>
CC: Giovanni Tummarello <g.tummarello@gmail.com>, semantic-web@w3.org

Is there some motivation for the MUST NOT cache constraint?

A thought is that there are quite complex HTTP cache control mechanisms 
which may not work correctly. But I suppose 302s are cached, and can be 
updated, and the behaviour is acceptable.... so that the same mechanisms 
should work with 303 (except for the prohibition).


thinking out loud, without reading the specs,


Jacek Kopecky wrote:
> Hi Giovanni,
> barring the change away from 303 for non-information resources, or a
> change to the cacheability of 303, one could indeed make a patch for
> squid.
> The way I'd go about it, not to break too much, would be to add a
> request ID header which would differ for different user requests, and
> the squid would cache everything within the same request ID, and it
> would follow the specs for different requests.
> The request ID would be treated as enabler for these "atomically
> cacheable" things (everything), atomically as in "in the same user
> request processing". And this could mean statefulness in squid (prolly 
> a very bad thing) if there was a requirement to interleave the
> processing of multiple user requests.
> But thinking about this, fixing 303 cacheability or maybe adding a
> cacheable 308 Description Elsewhere sounds easier now. 8-)
> Jacek
> On Tue, 2007-07-10 at 01:20 +0100, Giovanni Tummarello wrote:
>> Hi Jacek,
>> unfortunately the "application cache" is not always possible. .
>> The key to cluster scalability is splitting jobs across the cluster 
>> nodes so each file is more or less processed per so.
>> Web architecture then says that if you want to go fast.. you can cache.. 
>> so one puts a large proxy where all the nodes in theory can feed. This 
>> is what we thought we'd do.. just to find out that each process was 
>> running a few dozen times slower than what it could (to say nothing on 
>> the remote hits which is the real problem) due to squid rightfully 
>> refusing to cache 303.
>> We could write a "semantic web patch" for squid to explicitly violate a  
>> MUST NOT.. but.. :-)
>> .
>> Giovanni

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Received on Tuesday, 10 July 2007 12:45:28 UTC

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