- From: <Patrick.Stickler@nokia.com>
- Date: Wed, 8 Aug 2001 10:54:19 +0300
- To: champin@bat710.univ-lyon1.fr
- Cc: uri@w3.org, www-rdf-interest@w3.org
> In my opinion, the confusion is about *what* should be dereferenced. > Sometimes it is the named object, sometimes it is a > *description* of it. > Those are definitely different in my opinion. I fully agree. But they are also different from name versus location. > I'll take a trivial > example : > > ... > > Dereferencing http URIs with the HTTP protocol means for many people > "getting the actual object", like going to the pet shop, *not* looking > in the dictionnary. Using it the other way *is* confusing -- like > deciding that my homepage URL identifies myself, or http://www.w3.org/ > identifies the W3 consortiom. Good examples. Really, we have three different things going on here that I can see: (1) names versus locations (2) concepts versus various realizations of concepts (treating both the actual cat and a description of the cat as types of realizations of the shared concept of that cat) (3) characteristics of specific URI schemes (management, intended usage, inherent semantics, persistence of access, persistence of uniqueness, etc.) used for universal identifiers * Names may resolve to zero or more locations. * Locations resolve (dereference) to data content. Whether that data is a description of a thing or the thing itself is a separate issue. * URIs are used to provide identity to both names and locations. The original URN/URL distinction addressed #1 above, but seems to have been abandoned. Current URI definitions make no distinction whatsoever between instances of #2. Issues relating to #3 are practical in nature and are addressable irrespective of #1 and #2. Thus, in a way, the present discussion is actually outside the scope of and irrellevant to the (apparent) original issue of this thread -- namely the suitability of some URI schemes as reliably persistent and unambiguous universal identifiers ;-) Still, because the three issues above are *not* clear in the URI/RDF/SW literature, these discussions continue to merge. A generalized approach to addressing the above issues might be to define an ontology both for URL/URN type distinctions as well as for realization distinctions (instance vs description) -- possibly even a taxonomy of common URI semantics in general. XTM addresses the first two issues to a certain degree, but blurs their distinction. Cheers, Patrick -- Patrick Stickler Phone: +358 3 356 0209 Senior Research Scientist Mobile: +358 50 483 9453 Software Technology Laboratory Fax: +358 7180 35409 Nokia Research Center Video: +358 3 356 0209 / 4227 Visiokatu 1, 33720 Tampere, Finland Email: patrick.stickler@nokia.com
Received on Thursday, 9 August 2001 08:41:48 UTC