On 5/8/15 11:44 AM, Svensson, Lars wrote:
John, Kingsley,I wrote:OK, I can understand that. Does that mean that if I have under the same URI serve different representations (e. g. rdf/xml, turtle and xhtml+RDFa) all those representations must return exactly the same triples, or would it be allowed to use schema.org in the RDFa, W3C Organisation Ontology for rdf/xml and foaf when returning turtle? After all it's different descriptions of the same resource.John wrote:My take on this is each representation (with negotiation only on format via HTTP Accept header) *should* contain the same set of RDF statements (triples). Also one could define a different URL for each representation which can be linked to with Content-Location in the HTTP headers. We’re you to introduce an additional (orthogonal) way to negotiate a certain profile, this would be orthogonal to the format. Following on from above, one could then have a separate URL for each format-profile combination.Kingsley wrote:Yes. For the sake of additional clarity, how about speaking about documents and content-types rather than "representation" which does inevitably conflate key subtleties, in regards to RDF (Language, Notations, and Serialization Formats)?The terminology is fine with me, as long as we don't forget the entities we describe. So to repeat my question in another mail: I have an entity described by a (generic) URI.
You have an entity identified by a IRI in RDF. If you are adhering to Linked Open Data principles, said IRI would take the form of an HTTP URI.
Then I have three groups of documents describing that entity, the first uses schema.org, the second group uses org ontology and the third uses foaf.
You have an entity identified by an HTTP URI. The dual nature of this kind of URI enables it function as a Name. The fundamental quality (attribute, property, feature) of a Name is that its interpretable to meaning ie., a Name also has a dual (denotation and connotation feature) which is what an HTTP URI is all about, the only different is that denotation->connotation (i.e. name interpretation) occurs in the hypermedia medium provided by an HTTP network (e.g. World Wide Web). Net effect, the HTTP URI resolves to and document at a location on the Web (i.e, a document at a location, which is the URL aspect of this duality).
All documents are available as RDF/XML, Turtle and xhtml+RDFa. How does a client that knows only the generic URI for the resource tell the server that it prefers foaf in turtle and what does the server answer?
It can do stuff like this:curl -L -H "Accept: text/xml;q=0.3,text/html;q=1.0,text/turtle;q=0.5,*/*;q=0.3" -H "Negotiate: *" -I http://dbpedia.org/resource/Analytics
HTTP/1.1 303 See Other Date: Tue, 05 May 2015 16:01:06 GMT Content-Type: text/turtle; qs=0.35 Content-Length: 0 Connection: keep-alive Server: Virtuoso/07.20.3213 (Linux) i686-generic-linux-glibc212-64 VDB *TCN: choice** **Vary: negotiate,accept**Alternates*: {"/data/Analytics.atom" 0.500000 {type application/atom+xml}}, {"/data/Analytics.jrdf" 0.600000 {type application/rdf+json}}, {"/data/Analytics.jsod" 0.500000 {type application/odata+json}}, {"/data/Analytics.json" 0.600000 {type application/json}}, {"/data/Analytics.jsonld" 0.500000 {type application/ld+json}}, {"/data/Analytics.n3" 0.800000 {type text/n3}}, {"/data/Analytics.nt" 0.800000 {type text/rdf+n3}}, {"/data/Analytics.ttl" 0.700000 {type text/turtle}}, {"/data/Analytics.xml" 0.950000 {type application/rdf+xml}} Link: <http://mementoarchive.lanl.gov/dbpedia/timegate/http://dbpedia.org/resource/Analytics>; rel="timegate"
Location: http://dbpedia.org/data/Analytics.ttl Expires: Tue, 12 May 2015 16:01:06 GMT Cache-Control: max-age=604800
Best, Lars
-- Regards, Kingsley Idehen Founder & CEO OpenLink Software Company Web: http://www.openlinksw.com Personal Weblog 1: http://kidehen.blogspot.com Personal Weblog 2: http://www.openlinksw.com/blog/~kidehen Twitter Profile: https://twitter.com/kidehen Google+ Profile: https://plus.google.com/+KingsleyIdehen/about LinkedIn Profile: http://www.linkedin.com/in/kidehen Personal WebID: http://kingsley.idehen.net/dataspace/person/kidehen#this
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