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Re: SD vocab updates: dataset descriptions

From: Ivan Herman <ivan@w3.org>
Date: Mon, 23 Nov 2009 13:24:19 +0100
Message-ID: <4B0A7EF3.4020204@w3.org>
To: Alexandre Passant <alexandre.passant@deri.org>
CC: Gregory Williams <greg@evilfunhouse.com>, "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>
Heh:-) I was asking myself exactly the same question:-) That is why I
asked Greg to give an example...

I guess

sd:Service sd:defaultDataset [ ... ] .

(which is the current example) can also say

sd:Service sd:defaultDataset <URI> .

but I realized that does not necessarily sound right. <URI> is clearly
not the URI of the dataset itself, but a description thereof. So the
term's name is not really fine...

Again, I think an example would clarify Greg's thoughts...


Alexandre Passant wrote:
> Hi,
> On 21 Nov 2009, at 00:08, Gregory Williams wrote:
>> * Added URL variants of the above two terms: sd:defaultDatasetURL and
>> sd:availableDatasetURL. These are meant to allow linking not to the
>> dataset description directly but to a dereferencable document that
>> contains such descriptions. This allows the service description to be
>> kept small while providing access to very large dataset descriptions.
> I'm not sure I understand the different between the dataset description
> and a document that contains the description.
> It seems that the second one (the document about the description) is
> what we should get when we dereference the first one (the URI of the
> description) so why do we need a new property / URI here ?
> Alex.
>> * Added sd:defaultGraph term for linking a sd:Dataset with a
>> description of the default graph in a dataset. For now I'm leaving the
>> rdfs:range of this term open, allowing vocabularies like voiD to do it
>> themselves.
>> I'd like to get some feedback on these changes from the group. In
>> particular,  I'm curious about people's feelings on two issues:
>> (1) should the use of sd:availableDataset imply that the endpoint will
>> only allow use of the named graphs in FROM/FROM NAMED clauses, or
>> could it be used simply to link to locally cached/generated
>> descrptions of commonly used datasets? If the latter, we (or somebody
>> else) could coin a sd:feature IRI to indicate that an endpoint has the
>> ability to dereference graph URLs.
>> (2) How do people feel about the URL variants of the dataset
>> properties? I know several people had indicated that they wanted a way
>> to link to dataset descriptions without including them in the service
>> description and these terms were created to satisfy that need.
>> However, the logistics of actually using the terms feel a bit strange
>> to me (do you just search for any dataset instance in the retrieved
>> RDF similar to how foaf:PersonalProfileDocument is used?) and there
>> are other ways this could be handled (we might assume that if a
>> dataset description isn't in the SD RDF then the dataset IRI is
>> dereferencable and will return the description).
>> Thoughts?
>> thanks,
>> .greg
>> [1] Whiteboard darwing of the dataset description modeling from F2F2:
>> <http://thefigtrees.net/lee/dl/sparql-IMG00009-20091103-1508.jpg>. The
>> the unlabeled blue arc should be "default graph".
> -- 
> Dr. Alexandre Passant
> Digital Enterprise Research Institute
> National University of Ireland, Galway
> :me owl:sameAs <http://apassant.net/alex> .


Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
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Received on Monday, 23 November 2009 12:24:55 UTC

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