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Re: Status codes / IR vs. NIR -- 303 vs. 200

From: Lars Heuer <heuer@semagia.com>
Date: Wed, 10 Nov 2010 21:59:05 +0100
Message-ID: <273868088.20101110215905@semagia.com>
To: Kingsley Idehen <kidehen@openlinksw.com>
CC: public-lod@w3.org <public-lod@w3.org>
Hi Kingsley,

Thanks for your reply.

[GET <http://en.wikipedia.org/wiki/John_Lennon>]
> That's a Document Address, by default i.e., HTTP 200 OK response when 
> you HTTP GET.


>> Let's assume Wikipedia would return 303 like DBpedia does. Does it
>> solve the problem?

> No, they would have to implement a disambiguation heuristic using 303 
> that separates Document Address from Entity Name, assuming they adopt 
> what is known as a slash terminated style of URI re. Linked Data.

Why? Doesn't the response depend on the requested content/media type?
If I want an RDF/XML representation of the document, I can ask for

     Accept: application/rdf+xml

and Wikipedia would (ideally) return an RDF/XML representation of that
resource which tells me that John Lennon is a person who was born at
... murdered at ... was part of a group named ... etc.

>> I think, it does not solve it, since I cannot make
>> statements about the *page*
>> <http://en.wikipedia.org/wiki/John_Lennon>  (since I always get 303 and
>> an agent would interpret it as NIR).

> If they adopt the heuristic in play re. DBpedia, it will be fine.

> 1. http://dbpedia.org/resource/John_Lennon  -- Name
> 2. http://dbpedia.org/page/John_Lennon -- HTML Document with RDFa inside

I see, DBpedia provides different IRIs. That's fine. But it's not
possible to keep <http://en.wikipedia.org/wiki/John_Lennon> (or
<http://dbpedia.org/resource/John_Lennon> if that matters) and make
statements about that, right? I cannot make statements which are
interpreted rightly without an Internet connection. I need the status

> Personally, it can be solved at the application level by application 
> developers making a decision about the source of semantic fidelity i.e
> HTTP or the Data itself.

To take an practical example: If I want to make statements about the
following NIR:


What would I have to do? Do I need a redirect? Why? If the above
mentioned IRI would return RDF/XML (or any other media type requested
by the client), why do I need a 303? 200 + requested media type +
content should be enough, shouldn't it?

> Ian is indicating that RDF based Linked Data should dog-food i.e., if 
> RDF formats are about the content of structured data documents,  where
> the data describes itself, who is HTTP to determine otherwise re. Name
> or Address?  :-)

I am unsure if I am falling into the same trap?!?

Side note: Each subject/object needs a GET (assuming that predicates
are always NIRs) to interpret the statement correctly... Does it
scale? Let's assume you'd send me a DBpedia dump. I cannot interpret
it correctly, unless I have an Internet connection?

Best regards,
Received on Wednesday, 10 November 2010 21:04:25 UTC

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