answers to usual issues in getting started with consuming linked data

ISWC 2009 Tutorial "How to Consume Linked Data on the Web"

GettingStarted

Issues people have when they want to start


Getting Started

Finding URIs

Finding Additional Data

Finding SPARQL Endpoints


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

● Search engines for the Web of Linked Data 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


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>


Getting Started

Finding URIs





● 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

● Use content negotiation

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

GET /?uri=http://dbpedia.org/... HTTP/1.1Host: sameas.orgAccept: application/rdf+xml



● Search engines for the Web of Linked Data provide URI-based search for data from different sources● Sindice http://sindice.com


Getting Started

Finding URIs





● 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

Technology

web of linked data iswc

linked data sources

uris iswc

additional data problem

additional data search

xml iswc

data source specific

query berlinfalcons