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WWW 2012 Tutorial
Schema Mapping with SPARQL 1.1
Andreas Schultz(Freie Universität Berlin)
Outline
Why Do We Want to Integrate Data? Schema Mapping Translating RDF Data with SPARQL 1.1 Mapping Patterns
Motivation
Web of Data is heterogeneous Many different and overlapping ways to
represent information
Distribution of the most widely used vocabularies
Data is represented...
Using terms from a wide range of vocabularies Using diverging structures With values of different (data type) formats Fine grained vs. coarse grained Using different measuring units
Naming Differences
SELECT ?longTrack ?runtime{ { ?longTrack mo:duration ?time
} UNION {
?longTrack dbpedia-owl:runtime ?time
} FILTER (?track > 300)}
Structural Differences
dbpedia:Three_Little_Birds dbpedia-owl:musicalArtist dbpedia:Bob_Marley_&_The_Wailers .
dbpedia:Bob_Marley_&_The_Wailers foaf:made dbpedia:Three_Little_Birds .
Value Level Differences
“2012-04-15” vs. “2012-04-15”^^xsd:date “John Doe” vs. “John Doe”@en 20 in Celcius vs. 68 in Fahrenheit “Doe, John” vs. “John Doe”
Outline
Motivation Schema Mapping Translating RDF Data with SPARQL 1.1 Mapping Patterns
Schema Mapping
For data translation:
A mapping specifies how data under a source representation is translated to a target
representation, that is, the representation that you or your application expects.
Ways to Express Executable Mappings for RDF Data
Ontology constructs OWL, RDFS (rdfs:subClassOf, rdfs:subPropertyOf)
Rules SWRL RIF
Query Languages SPARQL 1.1
Outline
Motivation Schema Mapping Translating RDF Data with SPARQL 1.1 Mapping Patterns
Data Translation with SPARQL 1.1
Nearly W3C Recommendation status Many scalable SPARQL engine
implementations out there Data translation with SPARQL CONSTRUCT Huge improvements to version 1.0 regarding
data translation
How to Use SPARQL Construct Mappings Ideally
SELECT ?longTrack ?runtimeFROM { Construct { ?subj target:relevantProperty ?obj } WHERE { ?subj sour:relProperty ?obj } } WHERE { ?subj target:relevantProperty ?obj . …}
How to Use SPARQL Construct Mappings in Practice
SELECT ?longTrack ?runtimeFROM { Construct { ?subj target:relevantProperty ?obj } WHERE { ?subj sour:relProperty ?obj } } WHERE { ?subj target:relevantProperty ?obj . …}
Possibilities
Execute all SPARQL Construct queries on the source data set(s) to generate local versions of the target data set(s)
Optionally merge multiple target data sets into one
Reference these files in FROM clause Possibility we won't cover: Write the results
directly into a RDF store and query the store.
1. Transform Data Sets with ARQ
query –query=constructQuery.qry –data=sourceDataset.nt > targetDataset.ttl
# Execute more queries
…
2. Use Target Data Set Files in Query
SELECT ?longTrack ?runtimeFROM <targetDataset.ttl>FROM …WHERE { ?subj target:relevantProperty ?obj . …}
Outline
Motivation Schema Mapping Translating RDF Data with SPARQL 1.1 Mapping Patterns
Pattern based approach
Presentation of common mapping patterns Ordered from common to not so common Learn how to tackle these mapping patterns
with SPARQL 1.1
Simple Renaming Mapping Patterns
Rename Class / Property
Substitute the class or property URI
src:inst a mo:MusicArtist
src:inst a dbpedia-owl:MusicalArtist
Rename Class
SPARQL Mapping:
CONSTRUCT {
?s a mo:MusicArtist
} WHERE {
?s a dbpedia-owl:MusicalArtist
}
Rename Property
SPARQL Mapping:
CONSTRUCT {
?s rdfs:label ?o
} WHERE {
?s freebase:type.object.name ?o
}
Structural Mapping Patterns
Rename Class based on Property Existence
Rename class based on the existence of a property relation.
dbpedia:William_Shakespeare a fb:people.deceased_person .
dbpedia:William_Shakespeare a dbpedia-owl:Person ; dbpedia-owl:deathDate "1616-04-23"^^xsd:date .
Rename Class based on Property
SPARQL Mapping:
CONSTRUCT {
?s a freebase:people.deceased_person
} WHERE {
?s a dbpedia-owl:Person ; dbpedia-owl:deathDate ?dd .
}
Rename Class based on Value
Instances of the source class become instances of the target class if they have a specific property value.
gw-p:Kurt_Joachim_Lauk_euParliament_1840_P ; a fb:government.politician .
gw-p:Kurt_Joachim_Lauk_euParliament_1840_P a gw:Person ; gw:profession "politician"^^xsd:string .
Rename Class based on Value
SPARQL Mapping:
CONSTRUCT {
?s a fb:government.politician
} WHERE {
?s a gw:Person ; gw:profession "politician"^^xsd:string .
}
Reverse Property
The target property represents the reverse relationship regarding the source property.
dbpedia:Joey_Castillo mo:member_of dbpedia:Queens_of_the_Stone_Age .
dbpedia:Queens_of_the_Stone_Age dbpedia-owl:currentMemberdbpedia:Joey_Castillo .
Reverse Property
SPARQL Mapping:
CONSTRUCT {
?s mo:member_of ?o
} WHERE {
?o dbpedia-owl:currentMember ?s
}
Resourcesify
Represent an attribute by a newly created resource that then carries the attribute value.
dbpedia:The_Usual_Suspects po:version _:new ._:new po:duration 6360.0 .
dbpedia:The_Usual_Suspects dbpedia-owl:runtime 6360.0 .
Resourcesify
SPARQL Mapping:
CONSTRUCT {
?s po:version _:newversion . _:newversion po:runtime ?runtime .
} WHERE {
?s dbpedia-owl:runtime ?runtime .
}
Deresourcesify
Inverse pattern to the Resourcesify pattern.
dbpedia:John_F._Kennedy_International_Airport lgdp:owner "New York City" .
dbpedia:John_F._Kennedy_International_Airport dbpedia-owl:city dbpedia:New_York_City .dbpedia:New_York_City rdfs:label "New York City" .
Deresourcesify
SPARQL Mapping:
CONSTRUCT {
?s lgdp:owner ?cityLabel .
} WHERE {
?s dbpedia-owl:city ?city . ?city rdfs:label ?cityLabel .
}
Value Transformation based Mapping Patterns
SPARQL 1.1 functions
SPARQL 1.1 offers functions covering:
RDF terms (str, lang, IRI, STRDT etc.)
Strings (SUBSTR, UCASE etc.)
Numerics (abs, round etc.)
Dates and Times (now, year, month etc.)
Hash Functions (SHA1, MD5 etc.)
XPath Constructor Functions (xsd:float etc.)
Transform Value 1:1
Transform the (lexical) value of a property.
dbpedia:The_Shining_(film) movie:runtime 142 .
dbpedia:The_Shining_(film)dbpedia-owl:runtime 8520 .
Transform Value 1:1
SPARQL Mapping:
CONSTRUCT {
?s movie:runtime ?runtimeInMinutes .
} WHERE {
?s dbpedia-owl:runtime ?runtime . BIND(?runtime / 60 As ?runtimeInMinutes)
}
BIND( Expression As ?newVariable )
Transform Literal to URI
Transform a literal value into a URI.
dbpedia:Von_Willebrand_disease diseasome:omim <http://bio2rdf.org/omim:193400> .
dbpedia:Von_Willebrand_diseasedbpedia-owl:omim 193400 .
Also 1:1 transformation pattern!
Transform Literal to URI
SPARQL Mapping:
CONSTRUCT {
?s diseasome:omim ?omimuri .
} WHERE {
?s dbpedia-owl:omim ?omim . BIND(IRI(concat(“http://bio2rdf.org/omim:”, str(?omim))) As ?omimuri)
}
Construct Literals
SPARQL 1.1 offers several functions to construct literals:
STR – returns the lexical form → plain literal STRDT – construct data type literal STRLANG – construct literal with language tag
Cast to another Datatype
fb:en.clint_eastwood dbpedia-owl:birthDate “1930-05-31”^^xsd:date .
fb:en.clint_eastwoodfb:people.person.date_of_birth
“1930-05-31T00:00:00”^^xsd:dateTime .
Cast to another Datatype
SPARQL Mapping:
CONSTRUCT {
?s dbpedia-owl:birthDate ?date
} WHERE {
?s fb:people.person.date_of_birth ?dateTime . BIND(xsd:date(?dateTime) As ?date)
}
Transform Value N:1
dbpedia:William_Shakespeare foaf:name "Shakespeare, William" .
dbpedia:William_Shakespeare foaf:givenName "William" ; foaf:surname "Shakespeare" .
Transform multiple values from different properties to a single value.
Transform Value N:1
SPARQL Mapping:
CONSTRUCT {
?s foaf:name ?name
} WHERE {
?s foaf:givenName ?givenName ; foaf:surname ?surname . BIND(CONCAT(?surname, “, ”, ?givenName) As ?name)
}
Aggregation based Mapping Pattern
Aggregation
fb:en.berlin_u-bahndbpedia-owl:numberOfLines 2 .
fb:en.berlin_u-bahn fb:metropolitan_transit.transit_system.transit_lines fb:en.u1 ; fb:metropolitan_transit.transit_system.transit_lines fb:en.u3 .
Aggregate multiple values / occurrences into one value.
Aggregation
SPARQL Mapping:
CONSTRUCT {
?s dbpedia-owl:numberOfLines ?nrOfLines
} WHERE {
{ SELECT ?s (COUNT(?l) AS ?nrOfLines) { ?s fb:metropolitan_transit.transit_system.transit_lines ?l . } GROUP BY ?s }}
Data Cleaning
Data Cleaning
fb:en.jimi_hendrix dbpedia-owl:birthDate "1942-11-27"^^xsd:date
fb:en.jimi_hendrix fb:people.person.date_of_birth "1942-11-27" .
fb:en.josh_wink fb:people.person.date_of_birth "1970" .
Integrating data cleaning into a mapping.
Data Cleaning
SPARQL Mapping:
Construct {
?s dbpedia-owl:birthDate ?birthDate
} Where {
?s fb:people.person.date_of_birth ?bd . FILTER regex(?bd, “[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]”) BIND ((xsd:date(?bd)) As ?birthDate)
}
Questions?
