Hi Hans:
If you need use literals in your rdf store, you must use specific tags
for this purpose such as rdfs:label. In this way you keep the use of
your installation as a sparql endpoint with easy integration in the web
of data.
For instance you can add :
<rdfs:label> a member of the collection ABC_0123</rdfs:label> inside the
rdf:Description (don´t forget to add the :
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#";> to the RELS-EXT
datastream.
The you can query (via sparql):
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
select ?sujeto ?predicado ?objeto ?label from <#ri>
where{
filter regex (?label, 'ABC_0123' , 'i').
?sujeto ?predicado ?objeto.
?sujeto <rdfs:label> ?label
}
Saludos
Luis Zorita
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Many of you will think of a broken record when you hear this, but I never
> tire of saying it. {grin}
>
> If your need is essentially to put a literal property on objects (whether
> that be a title or the name of a collection to which the object belongs)
> you'll likely get better efficiency using a full-text index (e.g. Lucene or
> Zebra or the like). RDF stores really show their strength when supporting
> structural queries (e.g. "do _these_ relationships exist between _these_
> Fedora-objects?").
>
> To your questions:
>
> Presumably by "Does that mean that all Fedora relations must be uris?" you
> mean "Does that mean that [the objects of] all Fedora relations must be
> uris?". The answer is no. Certainly you can use literals as objects. But the
> relationships in the Fedora ontology (from which you drew
> <isMemberOfCollection>) have specified semantics that aren't in your control.
> In the case of <isMemberOfCollection>, the semantics include the expectation
> that the object of this predicate is indeed a Fedora-object, not a literal.
> So you should be using your own predicate because <isMemberOfCollection>
> doesn't have the meaning you want.
>
> - ---
> A. Soroka
> Software & Systems Engineering :: Online Library Environment
> the University of Virginia Library
>
> On Sep 6, 2012, at 8:27 AM, Scholte, Hans wrote:
>
>> Hi Egbert,
>>
>> Thanks for the answer.
>> Does that mean that all Fedora relations must be uris?
>> And if I want a literal then I must make my own predicate?
>>
>> I solved it now with
>>
>> <collection xmlns="info:dpc/relations#">ABC_0123</collection>
>>
>>
>> And that works for me (I don't want my collections to be objects in the
>> repository (at least, not yet) ).
>>
>>
>> Regards, Hans
>>
>>
>>
>>
>> -----Original Message-----
>> From: Egbert Gramsbergen [mailto:[email protected]]
>> Sent: September 06, 2012 12:31
>> To: [email protected]
>> Subject: Re: [fcrepo-user] question sparql/rels-ext
>>
>> Hello Hans,
>>
>> First of all: the object of this relation should not be al literal but an
>> uri resource.
>> So this for collection with PID my:collection:
>>
>> <isMemberOfCollection
>> xmlns="info:fedora/fedora-system:def/relations-external#"
>> rdf:resource="info:fedora/my:collection"/>
>>
>> and your query will be:
>> prefix e: <info:fedora/fedora-system:def/relations-external#>
>> select ?s
>> where { ?s e:isMemberOfCollection <info:fedora/my:collection>}
>>
>> Second: if the object of a relation is a plain literal you should not use
>> rdf:parseType="literal" because that is for xml. Just omit it:
>> <someRelation xmlns="some:namespace/">ABC_0123</someRelation>
>>
>> I hope this helps (and don't forget the info:fedora/ part like I do about 10
>> times a day)
>>
>> Egbert Gramsbergen
>> -----Original Message-----
>> From: hans [mailto:[email protected]]
>> Sent: donderdag 6 september 2012 10:45
>> To: [email protected]
>> Subject: [fcrepo-user] question sparql/rels-ext
>>
>> Hi,
>>
>> I'm trying to add some relations in my rels-ext like so:
>>
>> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";>
>> <rdf:Description
>> rdf:about="info:fedora/unicum:uba.items.12903be24c35550edd1be17a7b3d9f12">
>> <isMemberOfCollection
>> xmlns="info:fedora/fedora-system:def/relations-external#"
>> rdf:parseType="literal">
>> ABC_0123
>> </isMemberOfCollection>
>> </rdf:Description>
>> </rdf:RDF>
>>
>> When querying the triplestore with
>>
>> prefix e: <info:fedora/fedora-system:def/relations-external#>
>> select ?s
>> where { ?s e:isMemberOfCollection 'ABC_0123'}
>>
>> I have no results
>>
>> Querying with
>>
>> prefix e: <info:fedora/fedora-system:def/relations-external#>
>> select ?s ?o
>> where { ?s e:isMemberOfCollection ?o}
>>
>> gives me:
>>
>> "s","o"
>> info:fedora/unicum:uba.items.12903be24c35550edd1be17a7b3d9f12,ABC_0123
>>
>> Why do i not have a result with the first query?
>>
>> Regards, Hans
>>
>>
>>
>> --
>> View this message in context:
>> http://fedora-commons.1317035.n2.nabble.com/question-sparql-rels-ext-tp7578332.html
>> Sent from the Fedora Commons Users mailing list archive at Nabble.com.
>>
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