Re: Profiles in Linked Data

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