Answers to usual issues in getting started with consuming Linked Data (2010)

Getting
Started

Issues people have when they want to start

Getting Started

Finding URIs

Finding Additional Data

Finding SPARQL Endpoints

WWW 2010 Tutorial "How to Consume Linked Data on the Web"

Finding URIs
● Problem: What URIs exist that identify the thing
I'm interested in?
● Two options:
● Data source specific solutions
● Search engines for the Web of Linked Data


Finding URIs
● Some Linked Data sources provide a keyword-
based search for things in their dataset(s)
● RKB Explorer http://www.rkbexplorer.com/
● DBpedia http://lookup.dbpedia.org/


Finding URIs


Finding URIs
● What if there is no search possibility?
● You may try a SPARQL query:

SELECT DISTINCT ?s WHERE {
?s rdfs:label ?label .
FILTER regex( str(?label), "Berlin", "i" ) .
}


Finding URIs
provide keyword-based search for things in
different datasets
● Falcons http://iws.seu.edu.cn/services/falcons/
● Sindice http://sindice.com
● SWSE http://www.swse.org
● Watson http://watson.kmi.open.ac.uk


Finding URIs
● There are also APIs
● Falcons
http://iws.seu.edu.cn/services/falcons/api/index.jsp
● Sindice
http://sindice.com/developers/api
● Watson
http://watson.kmi.open.ac.uk/REST_API.html


<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:foaf="http://xmlns.com/foaf/0.1/"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<foaf:Document
rdf:about="http://iws.seu.edu.cn/services/falcons/api/objectsearch.jsp?query=Berlin">
<dc:description>Provides at most 10 objects hit by the query Berlin.</dc:description>
<dc:title>Objects hit by the query Berlin</dc:title>
<dc:creator>Falcons API</dc:creator>
</foaf:Document>
<rdf:Seq>
<rdf:li rdf:resource="http://dbpedia.org/resource/Berlin"/>
<rdf:li rdf:resource="http://dbpedia.org/resource/Category:Berlin"/>
<rdf:li rdf:resource="http://dbpedia.org/resource/Category:People_from_Berlin"/>
<rdf:li rdf:resource="http://www.deadjournal.com/interests.bml?int=berlin"/>
<rdf:li rdf:resource="http://dbtune.org/jamendo/tag/berlin"/>
<rdf:li rdf:resource="http://www4.wiwiss.fu-berlin.de/bookmashup/subject/Berlin"/>
<rdf:li rdf:resource="http://www.liveinternet.ru/journal_interest.php?interestid=51320"/>
<rdf:li rdf:resource="http://wiki.sembase.at/index.php/_Berlin"/>
<rdf:li rdf:resource="http://dbpedia.org/resource/Category:Berlin_U-Bahn_stations"/>
<rdf:li rdf:resource="http://dbpedia.org/resource/Category:Berlin_culture"/>
</rdf:Seq>
</rdf:RDF>

● Problem: Given a URI, where do I find
more data as what is available
by looking it up?
● Three options:
● Follow links (e.g. rdfs:seeAlso, owl:sameAs)
● Use a co-reference service
● Use a search engine for the Web of Linked Data


● Co-reference services find different URIs that
refer to the same thing
● sameAs http://sameas.org


● There is also an API
● Specify the preferred format in the URI
http://sameas.org/rdf?uri=http://dbpedia.org/resource/Berlin
http://sameas.org/n3?uri=http://dbpedia.org/resource/Berlin
http://sameas.org/json?uri=http://dbpedia.org/resource/Berlin

● Use content negotiation
GET /?uri=http://dbpedia.org/... HTTP/1.1
Host: sameas.org
Accept: application/rdf+xml

provide URI-based search for data from
different sources
● Sindice http://sindice.com


Finding SPARQL Endpoints
● Look at:
http://esw.w3.org/topic/SparqlEndpoints

● SPARQL 1.1 Service Description
● Vocabulary of Interlinked Datasets (voiD)


Answers to usual issues in getting started with consuming Linked Data (2010)

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