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Re: Linked Data on qdos.com

From: Richard Cyganiak <richard@cyganiak.de>
Date: Sun, 2 Dec 2007 17:54:33 +0000
Cc: Damian Steer <damian.steer@hp.com>, Chris Bizer <chris@bizer.de>, semantic-web <semantic-web@w3.org>
Message-Id: <8F0797A5-30DA-4C2F-9826-7E41E1E8066B@cyganiak.de>
To: Steve Harris <steve.harris@garlik.com>

Steve,

A very interesting dataset. I see that there are DBpedia links now,  
cool! However ...

On 29 Nov 2007, at 16:50, Steve Harris wrote:
>>>>> http://qdos.com/celeb/8340a9fc46297f805e66b6f9e89feb80 owl:sameAs
>>>>> http://dbpedia.org/resource/Moby
>>>> I really don't think you mean that :-)
>>>>
>>>> They are primarily about the same thing, I take it. Maybe
>>>> http://qdos.com/celeb/8340a9fc46297f805e66b6f9e89feb80 skos:subject
>>>> http://dbpedia.org/resource/Moby?
>>>
>>> I assume from Steve's RDF that
>>> http://qdos.com/celeb/8340a9fc46297f805e66b6f9e89feb80 identifies  
>>> Moby as a
>>> person (a non-information resource) and not the HTML document  
>>> describing
>>> Moby.
>>
>> Ah, apologies. Scratch what I said. I thought such URIs had to 303.
>
> That URI situation is a bit ugly, I had to trade of shorter/neater  
> profile URIs against being more easily able to distinguish between  
> HTML pages and URIs for people. Brevity won.

At the moment, unfortunately, the URI scheme is broken. It uses the  
same URI to identify two different things, a web document and a  
person. Web documents are different things than the things talked  
about in the document -- that's a fundamental axiom.

Let's look at qdos URIs ...

That's clearly a web document (available in HTML and Turtle):
http://qdos.com/celeb/8340a9fc46297f805e66b6f9e89feb80

That's the Turtle-only version of that web document:
http://qdos.com/celeb/8340a9fc46297f805e66b6f9e89feb80/turtle

The Turtle data is confused about wether that first URI identifies a  
document or a person. It has some data about the web document (e.g.  
date, creator) and some data about the person (name, homepage).

Fortunately, fixing this is fairly easy:

1. Make up your mind which properties are properties of the person,  
and which are properties of the QDos web page. I'd argue that almost  
all are about the person.

2. Use http://qdos.com/celeb/834...3b80#person as the URI for all the  
things where you mean the person.

3. Add a triple that relates the document and the person, e.g. <... 
3b80> foaf:primaryTopic <...3b80#person>.

Optionally, I'd suggest a few additional things:

4. A triple <...3b80#person> rdf:type foaf:Person would be helpful.

5. The HTML page could include an autodiscovery link to the RDF in the  
<head>:

    <link rel="alternate" type="application/x-turtle" href="...3b80/ 
turtle" />

6. Yes, RDF/XML output would be *very* helpful and is pretty much  
needed to be compatible with the rest of the Linking Open Data  
project. RDF/XML can be serialized in a simple line-by-line way, just  
like N-Triples (only much uglier).

I realize that it's not always easy to justify spending time on the  
subtleties of semwebby things, but I think it's important to get this  
right.

All the best,
Richard



>
>
> I would also have like to have gone with human readable URIs (eg / 
> people/Fred_Blogs) ala wikipedia, but it adds complexity in some  
> areas, and we were very short of time.
>
> - Steve
>
>
Received on Sunday, 2 December 2007 17:55:23 GMT

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