> Today the Getty released the Art and Architecture Thesaurus as Linked Open
> Data [1].
Releasing the Getty Thesaurus as linked data is very interesting, and after
visiting the blog posting I discovered a SPARQL endpoint to the data. [2] Yet,
I seem to always have problems exploring SPARQL endpoints without having an
in-depth and thorough knowledge of the underlying ontologies. Is this just me,
or am I missing something?
For example, without knowing anything, I think I can submit a SPARQL query such
as the following to just about any SPARQL endpoint to get an overview of the
triple store’s ontologies:
SELECT DISTINCT ?class
WHERE { ?subject a ?class }
ORDER BY ?class
This query uses the SPARQL short-hand notation of “a” to denote the RDF
predicate equal to rdf:typeOf, which I assume will be in just about every
triple store. Correct? Applying this query to the Getty SPARQL endpoint returns
a list of (hopefully) actionable URIs describing all the ontologies used in the
triple store.
I can submit the following SPARQL query to just about any triple store to get a
list of all the predicates used in the triple store, but the query usually
never returns; it probably creates a heck of a lot of work on the endpoint’s
backend. Each one of these predicates ought to be described in greater detail
in the actionable URIs from Query #1. Correct?
SELECT DISTINCT ?property
WHERE { ?subject ?property ?object }
ORDER BY ?property
Given these ontologies (classes) and properties (relationships), I ought to be
able to navigate around the triple store discovering cool information, but I
find the process to be very difficult. Here are a few queries:
# list of concepts
SELECT *
WHERE { ?s a <http://vocab.getty.edu/ontology#Concept> }
# all about the English phrase founding tools
SELECT *
WHERE { ?s ?p "founding tools"@en }
# uri for founding tools
SELECT ?uri
WHERE { ?uri rdfs:label "founding tools"@en }
I find this process to be painful. To what degree am I still to much a novice
at SPARQL, and to what degree do I need to have an intimate knowledge of the
ontologies before I can create meaningful queries? To what degree do more
user-friendly front-ends need to be created? In order for URIs to replace
literals in RDF, there will need to be much easier to use interfaces to triple
stores. Correct? Like the need for a data dictionary and entity-relationship
diagram in searching of relational databases vis SQL, to what degree do I
really need to know and understand the supporting ontologies before I can make
meaningful sense of a triple store?
Put another way, is there some set of basic/rudimentary queries I can send to
SPARQL endpoints, get results, and begin to drill down without really knowing
the ontologies? I’m stymied in this regard.
[1] announcement -
http://blogs.getty.edu/iris/art-architecture-thesaurus-now-available-as-linked-open-data/
[2] data home - http://vocab.getty.edu
—
Eric Lease Morgan
University of Notre Dame
