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Re: Understanding RDF

From: Aaron Swartz <me@aaronsw.com>
Date: Tue, 26 Nov 2002 12:11:09 -0600
Cc: www-archive@w3.org
To: Ian Hickson <ian@hixie.ch>
Message-Id: <707FEF0D-016A-11D7-AAEC-003065F376B6@aaronsw.com>

> My problem is with things like "how do I represent _me_ in RDF?"

Hm, I'll see if I can think of some more stuff along these lines to add.

You represent you by giving yourself a URI and then saying stuff about 
it

p:Hixie rdf:type foaf:Person .
p:Hixie foaf:homepage <http://index.hixie.ch/> .
p:Hixie dc:title "Ian Hickson" .
p:Hixie ex:coolnessLevel ex:VeryHigh .
...

>    <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>                 xmlns:dc="http://purl.org/dc/elements/1.1/"
>        <rdf:Description
>            about="http://ln.hixie.ch/?start=1038263537&amp;count=1"
>            
> dc:identifier="http://ln.hixie.ch/?start=1038263537&amp;count=1"
>            dc:title="Why semantic markup is so important"
>            dc:date="2002-11-25T22:32:17+00:00"/>
>        </rdf:RDF>
>
> ...what is the difference between "about", "resource" and 
> "dc:identifier",
> how do I get information out of the date, what's a Description, _why_ 
> or
> _how_ would I subclass, how do I tell, etc.

"about" (which really should be rdf:about) is pointing to the URI of 
the subject. I don't see resource here but similarly it points to the 
object. dc:identifier shouldn't be used to point to URIs in RDF. The 
date is in standard W3CDTF format[1]. A Description is basically an 
element saying "OK, I'm gonna start making RDF statements now, watch 
out". You subclass when an existing term is useful but not specific 
enough (like you might make a loc:issn subproperty of dc:identifier 
because dc:identifier is pretty vague). How is covered in the primer 
primer, I thought. What do you want to tell?

[1] http://www.w3.org/TR/NOTE-datetime

> Basically, the theory is great, but how do I actually _use_ this thing.

1. provide information
2. parse the information
3. build cool apps that use the information

Same as any other format, I think.
-- 
Aaron Swartz [http://www.aaronsw.com]
Received on Tuesday, 26 November 2002 13:11:11 GMT

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