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Re: Requirements for a possible "RDF 2.0"

From: Dan Brickley <danbri@danbri.org>
Date: Thu, 14 Jan 2010 16:00:35 +0100
Message-ID: <eb19f3361001140700o59619561nf5a2b68396aa4982@mail.gmail.com>
To: Danny Ayers <danny.ayers@gmail.com>
Cc: Steve Harris <steve.harris@garlik.com>, Semantic Web <semantic-web@w3.org>
On Thu, Jan 14, 2010 at 3:53 PM, Danny Ayers <danny.ayers@gmail.com> wrote:
> 2010/1/14 Steve Harris <steve.harris@garlik.com>:
>
>>> * improved support for named graphs - essentially bringing the
>>> constructs included in SPARQL back into RDF core (including support
>>> for named graphs in RDF/XML, done in a manner that would be
>>> backwards-compatible if at all possible)
>>
>> I'm not really sure how that fits all together. If you dereference some URI,
>> and get back a RDF/XML document that includes other named graphs, what then?
>> Surely the grph URI of the document you fetched you be the URI you
>> dereferenced.
>
> That's certainly the elegant intuitive approach. Maybe I'm making the
> mistake of engineering for engineering's sake, but I suspect there is
> a role for multiple graphs in a single document/at a single
> dereferenceable URI (dunno, somehow reflecting default graph/other
> named graphs in SPARQL).
>
> I don't have any genuine use cases.

There are two common patterns here:

1. You deref some URI, parse it for RDF, and put the triples into a
named graph whose URI is the same as the documents. When you reload
the data, you replace the triples.
2. You do the same, but you care about history so you put each set of
triples in a different graph, perhaps with a uuid:

I think the second case has a number of motivating scenarios. For example:

 * feeds, where eg. RSS1/Atom etc describe a 'moving window' on a
site, and it's worth keeping older copies of the graph
 * profiles, so you can see changes over time (did Alice add Bob as a
friend first, or vice-versa? who is Charlie no longer saying he is a
friend of?)
 * history: when was dct:audience first added to
http://purl.org/dc/terms/ ? when was foaf:geekcode first stated to be
'archaic' in the RDF from http://xmlns.com/foaf/0.1/ ?

The first case is nice and simple and hopefully self-motivating. But
keeping track of previous versions and being able to super-impose and
compare them is a core strength of SPARQL too...

cheers,

Dan

ps. Happy Birthday danny!
Received on Thursday, 14 January 2010 15:01:04 UTC

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