Core idea

• Structured data available on a global scale
• Connect related data items across multiple sources
• ?
• Profit

270a Cloud (statistical datasets)

RDF Triples

    <Subject> <Predicate> <Object> .

Vocabularies

• Decentralized invention (anyone can make theirs)
• Basics: RDF Syntax, RDF Schema
• Definitions for the relationship between things, or their classifications e.g.,Friend of a Friend (FOAF), Dublin Core Terms
• RDF Data Cube: Data structure definitions, code lists, datasets, ..
• SKOS: Code lists, and concepts can be reused
• VoID: vocabulary for dataset metadata

Vocabularies

• SIOC: vocabulary for online communities
• Schema.org: various - Google/Bing/Yahoo/Yandex initiative
• Open Graph Protocol: webpages as part of rich objects in social graph - Facebook

N-Triples

• Sarven's height is 1.65m.

  <http://csarven.ca/#i> 
    <http://dbpedia.org/property/height>
      "1.65m" .
  

• Ottawa is a city.

  <http://dbpedia.org/resource/Ottawa> 
    <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
      <http://dbpedia.org/ontology/City> .
  

Turtle

• Sarven is interested in electronic music, ..:

  @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
  @prefix foaf: <http://xmlns.com/foaf/0.1/> .
  @prefix wikipedia: <http://en.wikipedia.org/wiki/> .
  
  <http://csarven.ca/#i>
    rdf:type foaf:Person ;
    foaf:givenName "Sarven"@en ;
    foaf:interest wikipedia:Electronica , wikipedia:Monkey ;
    foaf:mbox <mailto:info@csarven.ca> ;
    foaf:account <http://twitter.com/csarven> .
  

Turtle

• Canada has capital Ottawa. Ottawa is a City.

  @prefix xsd: <http://www.w3.org/2001/XMLSchema#>
  @prefix dbr: <http://dbpedia.org/resource/> .
  @prefix dbp: <http://dbpedia.org/property/> .
  @prefix dbo: <http://dbpedia.org/ontology/> .
  @prefix geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> .
    dbr:Canada
      dbp:capital dbr:Ottawa ;
    dbr:Ottawa
      rdf:type dbo:City ;
      geo:lat "46.950001"^^xsd:float .
      geo:long "7.439583"^^xsd:float .
  

RDFa example

• Sarven is 1.65m.

  <p about="http://csarven.ca/#i">
      Sarven is <span property="dbp:height">1.65m</span></p>
  

• Ottawa is a city.

  <p about="dbr:Ottawa">
     typeof="dbo:City">Ottawa is a city.</p>
  

• Sarven is in Ottawa.

  <p about="http://csarven.ca/#i">
      Sarven is in <a rel="foaf:based_near"
                      href="dbr:Ottawa">Ottawa</a>.</p>
  

RDF/XML example

• Ottawa is a city.

  <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
    <rdf:Description rdf:about="http://dbpedia.org/resource/Ottawa">
      <rdf:type rdf:resource="http://dbpedia.org/ontology/City">
    </rdf:Description>
  </rdf:RDF>
  

• City is a Class of things.

    <rdf:Description rdf:about="http://dbpedia.org/ontology/City">
      <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#Class">
      <rdfs:label xml:lang="en">City</rdfs:label>
      <rdfs:label xml:lang="de">Stadt</rdfs:label>
    </rdf:Description>
  

Overview of the RDF formats

• Turtle: compact, human readable, triple pattern used in SPARQL
• N-Triples: verbose, small footprint (inspection, processing), exchange
• RDF/XML: verbose, existing toolchains, tree model
• RDFa: (X)HTML page, for humans and machines, can be treated like an API
• JSON-LD: client-side dev, tree model

SPARQL query example

• Select a list of subjects that is a city.

  SELECT ?city
  WHERE {
      ?city a <http://dbpedia.org/ontology/City> .
  }
  

SPARQL query result example

SPARQL query example

• People who were born in Ottawa before 1900:

  PREFIX dbo: <http://dbpedia.org/ontology/>
  PREFIX dbr: <http://dbpedia.org/resource/>
  SELECT ?name ?birth ?person WHERE {
      ?person dbo:birthPlace dbr:Ottawa .
      ?person dbo:birthDate ?birth .
      ?person foaf:name ?name .
      FILTER (?birth < "1900-01-01"^^xsd:date) .
  }
  ORDER BY ?name
      

  See results from DBpedia SPARQL Endpoint.

SPARQL query

• List of project names in countries which are classified to have low to middle income that are situated above the equator:

  PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
  PREFIX wgs: <http://www.w3.org/2003/01/geo/wgs84_pos#>
  PREFIX property: <http://worldbank.270a.info/property/>
  PREFIX country: <http://worldbank.270a.info/classification/country/>
  PREFIX income-level: <http://worldbank.270a.info/classification/income-level/>
  
  SELECT ?projectLabel ?countryLabel
  WHERE {
      GRAPH <http://worldbank.270a.info/graph/meta> {
          ?country property:income-level income-level:LMC .
          ?country wgs:lat ?latitude . FILTER (?latitude > 0)
          ?country skos:prefLabel ?countryLabel . }
      GRAPH <http://worldbank.270a.info/graph/world-bank-projects-and-operations> {
          ?project property:country ?country ; skos:prefLabel ?projectLabel . }
  }
  ORDER BY ?projectLabel
  

  See results at World Bank Linked Data SPARQL Endpoint.

SPARQL query: Federated

• CONSTRUCT {
  ..
  }
  WHERE {
      { SERVICE <http://data.linkedmdb.org/sparql> {
              SELECT * WHERE { .. }
        }
      }
      UNION
      { SERVICE <http://dbpedia.org/sparql> {
              SELECT * WHERE { .. }
        }
      }
  }
  

Provenance

• Data source, derived from
• License
• Related resource
• Creator, publisher
• Issued, modified dates
• PROV-O relationships:

Analysis user-interface (Plot) 1/3

http://stats.270a.info/analysis/worldbank:SP.DYN.IMRT.IN/transparency:CPI2009/year:2009

Analysis user-interface (Summary) 2/3

http://stats.270a.info/analysis/worldbank:SP.DYN.IMRT.IN/transparency:CPI2009/year:2009

Analysis user-interface (Provenance) 3/3

http://stats.270a.info/provenance/fa698e46868fe348865678884e89ef84b0be6c64