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Announcement: "Cool URIs for the Semantic Web" - W3C SWEO IG Note

From: Peter Ansell <ansell.peter@gmail.com>
Date: Wed, 9 Apr 2008 19:27:13 +1000
Message-ID: <a1be7e0e0804090227t5a59d829k62e9d61455fea74e@mail.gmail.com>
To: semantic-web@w3.org

On 09/04/2008, Dan Brickley <danbri@danbri.org> wrote:
 >
 >  Pat Hayes wrote:
 >
 > > Nice document. A few quibbles:
 > >
 > > ------------
 > >
 > > "When using 303 URIs for an ontology, like FOAF, network delay can reduce
 > a client's performance considerable."
 > >
 > > This sentence is not grammatical English. Rewrite to:
 > >
 > > When using 303 URIs for an ontology, like FOAF, network delay can
 > considerably reduce a client's performance.
 > >
 > > or:
 > >
 > > When using 303 URIs for an ontology, like FOAF, network delay can reduce a
 > client's performance to a considerable degree.
 > >
 > >
 >  My apologies for not reviewing the document more carefully. It seems to be
 > good stuff, but I missed this claim. And (as responsible party for FOAF ns)
 > think this overstates the problem.  Overstates it to a considerable degree,
 > even.
 >
 >  Clients can cache the 303 redirects, and the resulting URL's content can
 > also be cached. For a small ontology of 5 or 6 terms, this involves 5 or 6
 > HTTP redirects plus the main fetch. All cachable. For modest sized
 > ontologies like FOAF, with ~60 terms, it may be a slight nuisance, ... but
 > let's keep it in perspective: loading a single Flickr page probably involves
 > more HTTP traffic. And for massive ontologies, like the various wordnet
 > representations, breaking them up into parts has its own merits: why
 > download a description of 50000 classes just because you've encountered
 > @yone.


I always thought 303 redirects were not cacheable... "The 303 response
 MUST NOT be cached, but the response to the second (redirected)
 request might be cacheable"[1] Since the redirected request is not
 going to be the identity uri/url that is used on rdf documents, it is
 useless in the context of RDF resolution caching.

 It seems reasonably clear that the 303 redirect URL must always be
 resolved in order to determine whether your particular redirected and
 resolved url is still valid. This had to be in the minds of the TAG
 team when they decided to use this particular status code for the
 purposes of the semantic web communities identity crisis. In some ways
 it makes sense, but not in the bandwidth perspective. Not having a
 permanent cache of the actual document can be an issue for someone who
 actually wants to follow the standards and still have a reasonably
 concurrent system. I personally prefer 303 redirects for instance
 data, but not schema, as the schema should definitely be cacheable but
 the instance data is more likely to change in my opinion.

 [1] http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.4


 Peter
Received on Wednesday, 9 April 2008 09:27:46 UTC

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