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Re: caching HTTP 303 responses

From: Jacek Kopecky <jacek.kopecky@deri.org>
Date: Mon, 09 Jul 2007 21:43:52 +0200
To: Eyal Oren <eyal.oren@deri.org>
Cc: semantic-web@w3.org
Message-Id: <1184010232.18521.13.camel@localhost>

Hi Eyal, 

I expect that in one batch of dereferencing, you should be able to
optimalize. Caching is for subsequent requests, and I see those as
requests from the user, and if I understand your situation correctly,
your app does a big batch of dereferencing in response to a single user

You could easily do a simple queuing of URI requests in your app, and
all the requests for foaf:name would be treated as a single request and
done then. I expect that the situation should not change if some
foaf:name requests come after you've actually dereferenced it once, you
should still be able to use the same copy data you got because it was
retrieved in the scope of the same user request.

So I think what you're doing is not caching, in the same sense in which
HTTP caching is defined. You're closer to traversing a graph, and
foaf:name is an already visited node, to be ignored afterwards.

Hope it makes sense,

On Mon, 2007-07-09 at 20:26 +0100, Eyal Oren wrote:
> Hi,
> I've a question regarding serving RDF content using HTTP 303 redirects. For 
> example, foaf:name [1] redirects to http://xmlns.com/foaf/spec using HTTP 
> 303.  The, I believe relevant, RFC 2616 says that HTTP 303 responses MUST 
> NOT be cached, although the result may be cached [2].
> Does this mean, that I have to check every single time what foaf:name 
> redirects to? Or am I allowed to remember that foaf:name redirects to its 
> spec? Squid for example will not cache this redirect exactly because it is 
> a 303.  
> Unless I'm misunderstanding something, it seems that when I'm processing 
> lots of documents by de-referencing their URIs, I must dereference 
> foaf:name every single time, only to be redirected to the same location, 
> after which I can use my local copy.  Requesting this HTTP header using eg.  
> curl takes around 0.33s, which I'd think is rather a lot when processing 
> thousands of foaf files containing tens of foaf properties each.
> My question: why are HTTP 303 codes being suggested [3],[4] instead of 
> cacheable response such as 301 or was caching not an issue in drafting 
> these suggestions?
>  -eyal
> [1] http://xmlns.com/foaf/0.1/name
> [2] http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
> [3] http://www.w3.org/TR/swbp-vocab-pub/#redirect
> [4] http://www.dfki.uni-kl.de/~sauermann/2006/11/cooluris/
Received on Monday, 9 July 2007 19:44:08 UTC

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