Re: [Wikidata-tech] URL strategy

[Daniel Kinzler]

Am 13.06.2016 um 12:12 schrieb Richard Light:
> returns a list of person URLs.  So I'm happy.  However, I am still intrigued 
> as
> to the logic behind the redirection of the statement URL to the URL for the
> person about whom the statement is being made.

The reason is a practical one: the statement data is part of the data about that
person. It's stored and addressed as part of that person's information. We
currently do not have an API that would return only the statement data itself,
so if you dereference the statement URI, you get all the data we have on the
subject, which includes the statement.

This is formally acceptable: dereferencing the statement URI should give you the
RDF representation of that statement (and possibly more - which is the case
here). The statement URI does not resolve to the the subject or the object, but
to Statement itself, which is an RFC resource in it's own right.

Perhaps the confusion arises from the fact that the SPARQL endpoint offers two
views on Statements: the "direct" or "naive" mapping (using the wds prefix) in
which a Statement is modeled as a single triple, and does not have a URI of it's
own. And the "full" or "deep" mapping, where the statement is a resource in it's
own right, and we use several triples to describe its type, value, rank,
qualifiers, references, etc.

-- 
Daniel Kinzler
Senior Software Developer

Wikimedia Deutschland
Gesellschaft zur Förderung Freien Wissens e.V.

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Re: [Wikidata-tech] URL strategy

[Richard Light]

Hi,

To respond (partially) to my own question: SPARQL does do the job for 
me, e.g.:


select distinct ?person where {?person ?p ?prop .
?prop ps:P31 wd:Q5 .
} limit 100

returns a list of person URLs.  So I'm happy.  However, I am still 
intrigued as to the logic behind the redirection of the statement URL to 
the URL for the person about whom the statement is being made.


Thanks,

Richard

On 2016-06-13 10:51 AM, Richard Light wrote:


Hi,

I'm trying to get to grips with using Wikidata as a Linked Data 
resource, and would welcome some guidance.


Using the SPARQL end-point [1], I submit a query which looks for people:

PREFIX ps: 
PREFIX wd: 
describe ?s where {?s ps:P31 wd:Q5 .
} limit 100

The results give a set of wd:statement URLs (e.g. [2]), each of which 
has the required 'P31 Q5' property and four others (wikibase:rank, 
rdf:type and a couple of 'derived from' properties).  So this looks 
like a simple statement, which is in some sense a property of the 
person I am looking for.  I would then expect to refine my SPARQL 
query to pick up the person about whom this statement was made, and 
thereby get access to their other properties.


However, when I dereference the statement URL, I find that I have 
magically arrived at the URL of the person themselves [3].


While this is all very clever, it leaves me at a loss as to how I can 
access the properties of the person using SPARQL.


Thanks,

Richard

[1] https://query.wikidata.org/
[2] 
http://www.wikidata.org/entity/statement/q23-935f9100-47ca-f387-7946-45f9db09e81f
[3] https://www.wikidata.org/wiki/Q23 when accessed through the 
browser, or https://www.wikidata.org/wiki/Special:EntityData/q23 when 
accessed through curl with a suitable Accept header


--
*Richard Light*


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--
*Richard Light*
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[Wikidata-tech] URL strategy

[Richard Light]

Hi,

I'm trying to get to grips with using Wikidata as a Linked Data 
resource, and would welcome some guidance.


Using the SPARQL end-point [1], I submit a query which looks for people:

PREFIX ps: 
PREFIX wd: 
describe ?s where {?s ps:P31 wd:Q5 .
} limit 100

The results give a set of wd:statement URLs (e.g. [2]), each of which 
has the required 'P31 Q5' property and four others (wikibase:rank, 
rdf:type and a couple of 'derived from' properties).  So this looks like 
a simple statement, which is in some sense a property of the person I am 
looking for.  I would then expect to refine my SPARQL query to pick up 
the person about whom this statement was made, and thereby get access to 
their other properties.


However, when I dereference the statement URL, I find that I have 
magically arrived at the URL of the person themselves [3].


While this is all very clever, it leaves me at a loss as to how I can 
access the properties of the person using SPARQL.


Thanks,

Richard

[1] https://query.wikidata.org/
[2] 
http://www.wikidata.org/entity/statement/q23-935f9100-47ca-f387-7946-45f9db09e81f
[3] https://www.wikidata.org/wiki/Q23 when accessed through the browser, 
or https://www.wikidata.org/wiki/Special:EntityData/q23 when accessed 
through curl with a suitable Accept header


--
*Richard Light*
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