- From: Williams, Stuart <skw@hp.com>
- Date: Sat, 18 Oct 2003 18:32:53 +0100
- To: "'Sandro Hawke'" <sandro@w3.org>
- Cc: public-sw-meaning@w3.org
Hi Sandro, I think the wording in the referenced part of the WebArch doc is probably poorly expressed. The intend of the wording (as I understand it) is that if your given a URI for something (eg. with a representation, or out-of-band buy word of mouth etc.) then you should make references with it as given. Don't expect minor 'spelling' variations work work (hence the oaxaca/Oaxaca example. "Assigned" is probably the problem word... certainly the wording was not trying to suggest that there is one true canonical assignment of a URI to a given resource, only that if you 'obtain' for referring to a given resource, then you should use it as obtained... Does that help? Stuart -- > -----Original Message----- > From: Sandro Hawke [mailto:sandro@w3.org] > Sent: 16 October 2003 20:16 > To: public-sw-meaning@w3.org > Subject: Using two URIs for the same thing > > > > > I'm trying to do something totally reasonable with RDF and > the web, but I find myself going against a WebArch "good > practice". How could I possibly do this better? This smells > to me like a leak in WebArch notion of URIs, but I brought it > here because it's close enough to the hoses connecting > WebArch to RDF Semantics. > > We have four URIs: > > (M1) http://www.w3.org/2002/03owlt/equivalentClass/Manifest003#test > > This is what the WebOnt WG decided to name a particular OWL > test. You, as a human or machine, can learn more about the test > by dereferencing the URI (doing an HTTP GET). You should get > back some RDF/XML information about the test. A nicely > formatted version of that information (plus some more you'd get > by following some more links) is at: > > (H1) http://www.w3.org/TR/owl-test/L#equivalentClass-003 > > > Meanwhile, I've been assembling an aggregation of results for > OWL tests. As a human, today, you can visit > > (H2) http://www.w3.org/2003/08/owl-systems/test-results-out#test57 > > and see a row in a table about this test. You'll see it's a > pretty easy one. (Even my fairly-lame OWL reasoner passed it!) > > That's also not a very stable fragment id. Next week it might > land you on the results of another test. Sorry. But that's > part of what I'm trying to fix. > > Mostly, though, I want to allow more varied views of the same > data. I want to provide that data in RDF! I think the right > approach is to use a URI like > > (M2) > http://www.w3.org/2003/08/owl-systems/test/equivalentClass-003#test > > which can be used in RDF like M1, denoting the same test, but > which on dereference provides the test results data, along with > a triple saying it's owl:sameAs M1. [1] > > This seems reasonable, doesn't it? Two names for the same > thing; when you follow them you get information about the > thing; you get different information when you follow > different names. For some applications you'll use the first > name, for others the second. There are other people building > test-results browsers; they should have access to the same data. > > Useful, practical, easy to do, and... seemingly contrary to > TAG advice. The current WebArch document says, "If a URI has > been assigned to a resource, Web agents SHOULD refer to the > resource using the same URI, character for character." [2] > > So where is the breakdown here? > > Is this just the normal RFC 2119 escape from a "SHOULD": > "there may exist valid reasons in particular circumstances to > ignore a particular item, but the full implications must be > understood and carefully > weighed before choosing a different course." If so, I wish the > document would spell this out better, saying what some > reasonable exceptions might be. > > It seems to me a lot like having two web pages about the same > topic. Surely that's not something Web Arch wants to warn against. > > Maybe this is just a natural outgrowth of using URIs simultaneously as > (1) logical constant symbols naming objects in some domain of > discourse and (2) network addresses naming virtual end-points > for communication. Since we're using them in two ways at the > same time, they can be equivalent in one way, while being > completely different in > another. > > -- sandro > > > > [1] Actually, I want to use 303-See-Other redirection instead of a > fragment URI, so I can merge in the human-readable view as well, > but that's orthogonal, so I'll pretend otherwise for now. > [2] > http://www.w3.org/TR/2003/WD-webarch-20031001/> #identifiers-comparison >
Received on Saturday, 18 October 2003 13:35:21 UTC