On 5/11/15 11:54 AM, Svensson, Lars wrote:
Kingsley,

On Saturday, May 09, 2015 12:07 AM, Kingsley Idehen wrote:
[...]
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).
OK. I have an http URI that denotes an entity. Depending on the server 
configuration and what accept-headers I provide, the http dereferencing 
function returns a document at a location.

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
OK, I can see how setting the Accept-header negotiates the media type. If I 
understand correctly, the Negotiate-header gives the server and intermediate 
proxies a carte blanche to negotiate things any way they prefer. I don't see 
any header that tells the server what profile/shape/vocabulary the client 
prefers.

That's about a client negotiating different types of document content using a preference algorithm which in integral to Transparent Content Negotiation. It has nothing to do with a preferred vocabulary of terms e.g., dcterms vs schema.org in regards to terms used to describe something using RDF Language bases sentences/statements.

If you want an RDF based entity description, where the terms used come from a specific vocabulary, that's where you could leverage a query language e.g., SPARQL. Of course, there are those that don't want to use SPARQL which could then lead to yet another kind of "profile" relation object, but ultimately such use will only be the equivalent of ignoring the existence of "multiplication" and "division" in regards to arithmetic operations.

Conclusion: if folks want to build "profile" relations for selecting RDF content constructed using terms from a specific vocabulary, that's fine too, even though its utility would simply boil down to navigating politics.

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}}
Given this Alternates-header: how can  a client figure out what those 
representations look like (except for their media type)?

Your Web Browser (a client) understands text/html. A Browser and other HTTP clients apply the same content handling rules to other content types (e.g., those related to images, sound, and video etc..) .



Link:
<http://mementoarchive.lanl.gov/dbpedia/timegate/http://dbpedia.org/resour
ce/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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