- From: Tim Berners-Lee <timbl@w3.org>
- Date: Wed, 26 Dec 2001 17:56:59 -0500
- To: "Mark Nottingham" <mnot@mnot.net>, "Jonathan Borden" <jborden@mediaone.net>
- Cc: "Dan Brickley" <danbri@w3.org>, "Sean B. Palmer" <sean@mysterylights.com>, "Dan Connolly" <connolly@w3.org>, <www-rdf-interest@w3.org>
cwm has string:startsWith which you can combine with log:uri to get this effect for that example { ?x log:uri [ string:startsWith "http:" ] } log:implies { ?x a :Document } . Yes, a full URI parsing would of course be very interesting - kutgw Mark. For example, it would allow one to write the rules for a web server, or write rules to interpret the httpd.conf file or equivalent. Tim ----- Original Message ----- From: "Mark Nottingham" <mnot@mnot.net> To: "Jonathan Borden" <jborden@mediaone.net> Cc: "Tim Berners-Lee" <timbl@w3.org>; "Dan Brickley" <danbri@w3.org>; "Sean B. Palmer" <sean@mysterylights.com>; "Dan Connolly" <connolly@w3.org>; <www-rdf-interest@w3.org> Sent: Wednesday, December 26, 2001 4:42 PM Subject: Re: aboutEachPrefix? was Re: Namespaces wihtout "#" Was: Few CWM Bugs > > I've been playing with a means of deconstructing URIs so that one can > define rules about them in a much more fine-grained manner. Roughly, > what you'd like to do might look like: > > { ?x log:uri [ uri:scheme "http" ] } > log:implies > { ?x a :Document } . > > (there's some thought of pointing at the list of URI schemes at > w3.org, rather than a literal, to identify the scheme, but you get > the idea, hopefully). > > I have a CWM module that does uri:scheme. It gets more interesting > when you can break down the path into segments, etc., and test for > properties of the authority, but it's not there yet. > > Cheers, > > > > On Wed, Dec 26, 2001 at 01:41:01AM -0500, Jonathan Borden wrote: > > It seems to me that in order to say something like this in RDF we > > really do need the "aboutEachPrefix" construct, in which case one > > can: > > > > <rdf:Description rdf:aboutEachPrefx="http:"> > > <rdf:type rdf:resource="...#Document"> > > </rdf:Description> > > > > unfortunately it has been removed from the current RDF syntax. Can > > one state this using the current RDF? What I am looking for is an > > unambiguous, machine processable, mechanism for knowing types and > > other properties of URI subspaces (now that URIs are not opaque -- > > which is fine) > > > > Jonathan > > > > > > > True. A resource for a non-HTTP space can be whatever that URI > > > space says it is. It is just HTTP which really creates a world > > > of documents. > > > > > > mailto: for example, defines a space of mailboxes which are not > > > documents. I should have limited what I said to the http: space. > > > > > > Tim > > > > > > ----- Original Message ----- > > > From: "Jonathan Borden" <jborden@mediaone.net> > > > To: "Tim Berners-Lee" <timbl@w3.org>; "Dan Brickley" <danbri@w3.org> > > > Cc: "Sean B. Palmer" <sean@mysterylights.com>; "Dan Connolly" > > > <connolly@w3.org>; <www-rdf-interest@w3.org> > > > Sent: Saturday, December 22, 2001 10:39 AM > > > Subject: Re: Namespaces wihtout "#" Was: Few CWM Bugs > > > > > > > > > > Tim Berners-Lee wrote: > > > > > > > > > > > > > The second issue is more significant. In my worldview, > > > > > > > (which I claim to be (a) consistent and (b) useful) > > > > > > > http://example.org/x is a document. You can't reuse its > > > > > > > URI for an abstract thing without a change to HTTP. > > > > > > > > > > > > In-principle plausible, although _please_ define "document". > > > > > > > > > > I uyse the term "document" because unfortunately "resource" > > > > > has been used differently in URI and RDF specs. I mean by > > > > > "document" "resource" as in URI. DAML uses the term "Thing" > > > > > to mean what RDF terms a resource. > > > > > > > > This is really helpful, yet when I read the RFC 2396 definition > > > > of a resource I don't see how a resource can be _limited_ to > > > > only things which are documents: > > > > > > > > "A resource can be anything that has identity. Familiar > > > > examples include an electronic document, an image, a service > > > > (e.g., "today's weather report for Los Angeles"), and a > > > > collection of other resources. Not all resources are network > > > > "retrievable"; e.g., human beings, corporations, and bound > > > > books in a library can also be considered resources. " > > > > > > > > This language clearly states, to my very best reading, that a > > > > _document_ is a subClass of a _resource_ and a _human being_ is > > > > another subClass of > > > > _resource_. This is why I cannot understand why a plain old URI > > > > (i.e. without fragment identifer) cannot identify a person. > > > > Perhaps you are saying that the _type_ of resource is indicated > > > > by the URI scheme? i.e. that people would be indicated e.g. > > > > > > > > person://smith/joe > > > > > > > > > > > > > > When the content-type is RDF or N3, then a document can be > > > > > used to describe people and planes and ideas. These can be > > > > > identified (in N3) by using the localname of concept within > > > > > the document as a fragment identifier. (I think the same > > > > > should be true of RDF/XML). > > > > > > > > Ok, I buy this. Here you say that people, places and things can > > > > be identified by URI References. This still does not solve the > > > > problem that RFC 2396 says what URIs themselves may identify... > > > > > > > > > > >.The distinction is only useful if it can be defined clearly > > > > > > enough to implement to. > > > > > > > > > > Well, you certianly can't return a person across the net, so > > > > > the distinction is not that fine ;-) > > > > > > > > Again, RFC 2396 explicitly does not limit resources to things > > > > that are network retrievable, so I need more guidance here. > > > > > > > > Perhaps the problem is that many people treat RFCs as axioms > > > > and in trying to understand how 'logic on the Web' will work in > > > > practice, inconsistencies are problematic. > > > > > > > > Jonathan > > > > > > > > > > > > > > -- > Mark Nottingham > http://www.mnot.net/ > >
Received on Wednesday, 26 December 2001 17:57:22 UTC