Downloaded 41 times
![{
"@context" : "http://...wikidata.json",
"@graph" : [ {
"@id" : "wd:Q10514",
"wdt:P18" : "picture.jpg",
"wdt:P19" : "wd:Q14317",
"P569" : "1981-07-29"
}, {
"@id" : "wd:Q14317",
"wdt:P1082" : 220020,
"wdt:P1376" : "wd:Q3934",
"wdt:P2076" : 36
}
]
}
RDF syntaxes: JSON-LD
36^^xsd:integer
wdt:P2076
wd:Q10514 wd:Q3934
wdt:P19
wdt:P1376
"1981-07-29"^^xsd:date
220020^^xsd:integer
wdt:P1082
wdt:P18 wdt:P569
...jpg
BirthPlace
Picture
BirthDate
capital
temperature
population
Oviedo
Asturias
Fernando
Alonso
wd:Q14317](https://image.slidesharecdn.com/validatingrdfdatachallengesperspectives-190626182742/75/Validating-RDF-data-Challenges-and-perspectives-15-2048.jpg)
![RDF data model: Blank nodes
A statement about something
Example: "Alice knows someone who knows Bob"
:alice
schema:knows
:bob
schema:knows
:alice schema:knows _:x ;
_:x schema:knows :bob .
Notation (in Turtle)
:alice schema:knows [
schema:knows :bob
] .
x ( :alice :knows x
x :knows :bob )](https://image.slidesharecdn.com/validatingrdfdatachallengesperspectives-190626182742/75/Validating-RDF-data-Challenges-and-perspectives-19-2048.jpg)
![Example with more ShEx features
:AdultPerson EXTRA rdf:type {
rdf:type [ schema:Person ] ;
:name xsd:string ;
:age MinInclusive 18 ;
:gender [:Male :Female] OR xsd:string ;
:address @:Address ? ;
:worksFor @:Company + ;
}
:Address CLOSED {
:addressLine xsd:string {1,3} ;
:postalCode /[0-9]{5}/ ;
:state @:State ;
:city xsd:string
}
:Company {
:name xsd:string ;
:state @:State ;
:employee @:AdultPerson * ;
}
:State /[A-Z]{2}/
:alice rdf:type :Student, schema:Person ;
:name "Alice" ;
:age 20 ;
:gender :Male ;
:address [
:addressLine "Bancroft Way" ;
:city "Berkeley" ;
:postalCode "55123" ;
:state "CA"
] ;
:worksFor [
:name "Company" ;
:state "CA" ;
:employee :alice
] . Try it: https://tinyurl.com/yd5hp9z4](https://image.slidesharecdn.com/validatingrdfdatachallengesperspectives-190626182742/75/Validating-RDF-data-Challenges-and-perspectives-43-2048.jpg)
![Same example with blank nodes
Try it. RDFShape https://goo.gl/ukY5vq
prefix : <http://example.org/>
prefix sh: <http://www.w3.org/ns/shacl#>
prefix xsd: <http://www.w3.org/2001/XMLSchema#>
prefix schema: <http://schema.org/>
:UserShape a sh:NodeShape ;
sh:targetNode :alice, :bob, :carol ;
sh:nodeKind sh:IRI ;
sh:property [
sh:path schema:name ;
sh:minCount 1; sh:maxCount 1;
sh:datatype xsd:string ;
] ;
sh:property [
sh:path schema:email ;
sh:minCount 1; sh:maxCount 1;
sh:nodeKind sh:IRI ;
] .
:alice schema:name "Alice Cooper" ;
schema:email <mailto:alice@mail.org> .
:bob schema:firstName "Bob" ;
schema:email <mailto:bob@mail.org> .
:carol schema:name "Carol" ;
schema:email "carol@mail.org" .
Shapes graph
Data graph
](https://image.slidesharecdn.com/validatingrdfdatachallengesperspectives-190626182742/75/Validating-RDF-data-Challenges-and-perspectives-48-2048.jpg)
![Validation Report
The output of the validation process is a list of violation errors
No errors RDF conforms to shapes graph
[ a sh:ValidationReport ;
sh:conforms false ;
sh:result [
a sh:ValidationResult ;
sh:focusNode :bob ;
sh:message
"MinCount violation. Expected 1, obtained: 0" ;
sh:resultPath schema:name ;
sh:resultSeverity sh:Violation ;
sh:sourceConstraintComponent
sh:MinCountConstraintComponent ;
sh:sourceShape :hasName
] ;
...
[ a sh:ValidationReport ;
sh:conforms true
].](https://image.slidesharecdn.com/validatingrdfdatachallengesperspectives-190626182742/75/Validating-RDF-data-Challenges-and-perspectives-50-2048.jpg)
![SHACL processor
SHACL
Processor
Validation report
:UserShape a sh:NodeShape ;
sh:targetNode :alice, :bob, :carol ;
sh:nodeKind sh:IRI ;
sh:property :hasName,
:hasEmail .
:hasName sh:path schema:name ;
sh:minCount 1;
sh:maxCount 1;
sh:datatype xsd:string .
. . .
Shapes
graph
:alice schema:name "Alice Cooper" ;
schema:email <mailto:alice@mail.org>.
:bob schema:name "Bob" ;
schema:email <mailto:bob@mail.org> .
:carol schema:name "Carol" ;
schema:email <mailto:carol@mail.org> .
Data
Graph
[ a sh:ValidationReport ;
sh:conforms true
].](https://image.slidesharecdn.com/validatingrdfdatachallengesperspectives-190626182742/75/Validating-RDF-data-Challenges-and-perspectives-51-2048.jpg)
![Longer example
:AdultPerson EXTRA a {
a [ schema:Person ] ;
:name xsd:string ;
:age MinInclusive 18 ;
:gender [:Male :Female] OR xsd:string ;
:address @:Address ? ;
:worksFor @:Company + ;
}
:Address CLOSED {
:addressLine xsd:string {1,3} ;
:postalCode /[0-9]{5}/ ;
:state @:State ;
:city xsd:string
}
:Company {
:name xsd:string ;
:state @:State ;
:employee @:AdultPerson * ;
}
:State /[A-Z]{2}/
:AdultPerson a sh:NodeShape ;
sh:property [
sh:path rdf:type ;
sh:qualifiedValueShape [
sh:hasValue schema:Person
];
sh:qualifiedMinCount 1 ;
sh:qualifiedMaxCount 1 ;
] ;
sh:targetNode :alice ;
sh:property [ sh:path :name ;
sh:minCount 1; sh:maxCount 1;
sh:datatype xsd:string ;
] ;
sh:property [ sh:path :gender ;
sh:minCount 1; sh:maxCount 1;
sh:in (:Male :Female);
] ;
sh:property [ sh:path :age ;
sh:maxCount 1;
sh:minInclusive 18
] ;
sh:property [ sh:path :address ;
sh:node :Address ;
sh:minCount 1 ; sh:maxCount 1
] ;
sh:property [ sh:path :worksFor ;
sh:node :Company ;
sh:minCount 1 ; sh:maxCount 1
].
:Address a sh:NodeShape ;
sh:closed true ;
sh:property [ sh:path :addressLine;
sh:datatype xsd:string ;
sh:minCount 1 ; sh:maxCount 3
] ;
sh:property [ sh:path :postalCode ;
sh:pattern "[0-9]{5}" ;
sh:minCount 1 ; sh:maxCount 3
] ;
sh:property [ sh:path :city ;
sh:datatype xsd:string ;
sh:minCount 1 ; sh:maxCount 1
] ;
sh:property [ sh:path :state ;
sh:node :State ;
] .
:Company a sh:NodeShape ;
sh:property [ sh:path :name ;
sh:datatype xsd:string
] ;
sh:property [
sh:path :state ;
sh:node :State
] ;
sh:property [ sh:path :employee ;
sh:node :AdultPerson ;
] ;.
:State a sh:NodeShape ;
sh:pattern "[A-Z]{2}" .
In ShEx
In SHACL
Its recursive!!! (not well defined SHACL)
Implementation dependent feature
Try it: https://tinyurl.com/ycl3mkzr](https://image.slidesharecdn.com/validatingrdfdatachallengesperspectives-190626182742/75/Validating-RDF-data-Challenges-and-perspectives-53-2048.jpg)
Uploaded byJose Emilio Labra Gayo
Validating RDF data: Challenges and perspectives
The document discusses the challenges and perspectives of validating RDF data, focusing on the importance of making web information machine-processable. It outlines the RDF data model, its syntaxes (such as Turtle, JSON-LD, and RDF/XML), and highlights the role of technologies like SHACL and ShEx in defining and validating RDF graph structures. The document emphasizes the significance of knowledge graphs and semantic web technologies in the context of linked data and information retrieval.
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Validating RDF data: Challenges and perspectives
- 1. Validating RDF data: Challengesand perspectives Jose Emilio Labr Gayo WESO Research Group (WEb Semantics Oviedo) University of Oviedo, Spain
- 2. About me… Founded WESO(Web Semantics Oviedo) research group Practical applications of semantic technologies since 2004 Several domains: e-Government, e-Health Some books: "Web semántica" (in Spanish), 2012 "Validating RDF data", 2017 …and software: SHaclEX (Scala library, implements ShEx & SHACL) RDFShape (RDF playground) HTML version: http://book.validatingrdf.com Examples: https://github.com/labra/validatingRDFBookExamples
- 3. Contents Short intro tosemantic Web & knowledge graphs Short overview of RDF Understanding the RDF validation problem 2 technologies: ShEx/SHACL Challenges & perspectives
- 4. Semantic Web Vision ofthe Web as web of data Not only pages, but also data: linked data Data understandable by machines Related with: Big Data Artificial intelligence Knowledge representation Example: Wikipedia vs Wikidata Tim Berners-Lee Source: Wikipedia Source: http://www.internetlivestats.com/total-number-of-websites/ Date: 05/04/2019 (19:05h)
- 5. Who consumes Webinformation? People We access through some device ...and Machines They show us web pages (browsers) ...but also manage information (bots) Filtering content Doing suggestions ... "If Google doesn't understand your Web page, it almost doesn't exist"
- 6. Web information Documentos Information retrieval DocumentosDocumentos Posts Tweets Web pages ... Publish Web documents Reality Mentalmodel Web information must be machine-processable Semantic web technologies focus on how to achieve this goal Sensors Generate User Content generation & filtering
- 7. People vs Machines Programmedfor some tasks Predictable (no mistakes*) No problem with repetitive tasks Problems to understand the context Creativity, imagination Unpredictable (we do mistakes) We get tired with repetitive tasks Understanding based on context *when well programmed
- 8. Information understandable bymachines? Example: "Oviedo has a temperature of 36 degrees" Problem: Ambiguity and context identification Oviedo ? It can be... A city in Spain ...or a city in Florida, USA ...or a soccer player http://www.wikidata.org/entity/Q325997 http://wikidata.org/entity/Q14317 http://www.wikidata.org/entity/Q1813449 ...has a temperatrure of... https://www.wikidata.org/wiki/Property:P2076 Identifiers (URIs) in Wikidata Machine representation http://www.wikidata.org/entity/Q14317 https://www.wikidata.org/prop/direct/P2076 36^^<http://www.w3.org/2001/XMLSchema#integer>
- 9. Knowledge representation formachines Simple statement (triple 3 elements): subject, predicate, object http://www.wikidata.org/entity/Q14317 https://www.wikidata.org/prop/direct/P2076 subject predicate object 36^^<http://www.w3.org/2001/XMLSchema#integer> wd:Q14317 wdt:P2076 36^^xsd:integer wd: <http://www.wikidata.org/entity/> wdt: <https://www.wikidata.org/prop/direct/> xsd: <http://www.w3.org/2001/XMLSchema#> Prefix declarations help simplify long URIs
- 10. Knowledge graphs wd:Q14317 36^^xsd:integer wdt:P2076 wd:Q10514wd:Q3934 wdt:P19 wdt:P1376 "1981-07-29"^^xsd:date 220020^^xsd:integer wdt:P1082 wdt:P18 wdt:P569 ...jpg BirthPlace Picture BirthDate capital temperature population Oviedo Asturias Fernando Alonso Wikidata statistics (17-07-2019) 57,462,853 entities 728,979,397 triples Source: https://www.wikidata.org/wiki/Wikidata:Statistics Wikidata is an example of a knowledge graph There are a lot more: Open: DBpedia, BabelNet, etc Proprietary: Google, facebook, Microsoft, etc. also have knowledge graphs
- 11. Web information &knowledge graphs Documentos Information retrieval Knowledge graphs DocumentosDocumentos Posts Tweets Web pages ... Publish Web documents Reality Mental model Knowledge graphs are a key part of the Web nowadays Sensors Generate User Content generation & filtering
- 12. RDF RDF (Resource DescriptionFramework) Allows to represent knowledge graphs RDF data model = graph as a set of statements Predicates = URIs Several syntaxes Turtle, N-Triples, JSON-LD,... 36^^xsd:integer wdt:P2076 wd:Q10514 wd:Q3934 wdt:P19 wdt:P1376 "1981-07-29"^^xsd:date 220020^^xsd:integer wdt:P1082 wdt:P18 wdt:P569 ...jpg BirthPlace Picture BirthDate capital temperature population Oviedo Asturias Fernando Alonso wd:Q14317
- 13. prefix wd: <http://www.wikidata.org/entity/> prefixwdt: <https://www.wikidata.org/prop/direct/> prefix xsd: <http://www.w3.org/2001/XMLSchema#> wd:Q14317 wdt:P1082 220020 ; wdt:P2076 36 ; wdt:P1376 wd:Q3934 . wd:Q10514 wdt:P19 wd:Q14317 ; wdt:P569 "1981-07-29"^^xsd:date ; wdt:P18 <picture.jpg> . RDF syntaxes: Turtle 36^^xsd:integer wdt:P2076 wd:Q10514 wd:Q3934 wdt:P19 wdt:P1376 "1981-07-29"^^xsd:date 220020^^xsd:integer wdt:P1082 wdt:P18 wdt:P569 ...jpg BirthPlace Picture BirthDate capital temperature population Oviedo Asturias Fernando Alonso wd:Q14317
- 14. <http://www.wikidata.org/entity/Q14317> <https://www.wikidata.org/prop/direct/P1082> "220020"^^<http://www.w3.org/2001/XMLSchema#integer>. <http://www.wikidata.org/entity/Q14317> <https://www.wikidata.org/prop/direct/P1376> <http://www.wikidata.org/entity/Q3934> . <http://www.wikidata.org/entity/Q14317> <https://www.wikidata.org/prop/direct/P2076> "36"^^<http://www.w3.org/2001/XMLSchema#integer> . <http://www.wikidata.org/entity/Q10514> <https://www.wikidata.org/prop/direct/P18> <picture.jpg> . <http://www.wikidata.org/entity/Q10514> <https://www.wikidata.org/prop/direct/P19> <http://www.wikidata.org/entity/Q14317> . <http://www.wikidata.org/entity/Q10514> <https://www.wikidata.org/prop/direct/P569> "1981-07-29"^^<http://www.w3.org/2001/XMLSchema#date> . RDF syntaxes: N-Triples 36^^xsd:integer wdt:P2076 wd:Q10514 wd:Q3934 wdt:P19 wdt:P1376 "1981-07-29"^^xsd:date 220020^^xsd:integer wdt:P1082 wdt:P18 wdt:P569 ...jpg BirthPlace Picture BirthDate capital temperature population Oviedo Asturias Fernando Alonso wd:Q14317
- 15. { "@context" : "http://...wikidata.json", "@graph": [ { "@id" : "wd:Q10514", "wdt:P18" : "picture.jpg", "wdt:P19" : "wd:Q14317", "P569" : "1981-07-29" }, { "@id" : "wd:Q14317", "wdt:P1082" : 220020, "wdt:P1376" : "wd:Q3934", "wdt:P2076" : 36 } ] } RDF syntaxes: JSON-LD 36^^xsd:integer wdt:P2076 wd:Q10514 wd:Q3934 wdt:P19 wdt:P1376 "1981-07-29"^^xsd:date 220020^^xsd:integer wdt:P1082 wdt:P18 wdt:P569 ...jpg BirthPlace Picture BirthDate capital temperature population Oviedo Asturias Fernando Alonso wd:Q14317
- 16. <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:wdt="https://www.wikidata.org/prop/direct/" xmlns:wd="http://www.wikidata.org/entity/" xmlns:xsd="http://www.w3.org/2001/XMLSchema#"> <rdf:Description rdf:about="http://www.wikidata.org/entity/Q10514"> <wdt:P18>picture.jpg</wdt:P18> <wdt:P19> <rdf:Descriptionrdf:about="http://www.wikidata.org/entity/Q14317"> <wdt:P1082 rdf:datatype="http://www.w3.org/2001/XMLSchema#integer">220020</wdt:P1082> <wdt:P1376 rdf:resource="http://www.wikidata.org/entity/Q3934"/> <wdt:P2076 rdf:datatype="http://www.w3.org/2001/XMLSchema#integer">36</wdt:P2076> </rdf:Description> </wdt:P19> <wdt:P569 rdf:datatype=http://www.w3.org/2001/XMLSchema#date>1981-07-29</wdt:P569> </rdf:Description> </rdf:RDF> RDF syntaxes: RDF/XML 36^^xsd:integer wdt:P2076 wd:Q10514 wd:Q3934 wdt:P19 wdt:P1376 "1981-07-29"^^xsd:date 220020^^xsd:integer wdt:P1082 wdt:P18 wdt:P569 ...jpg BirthPlace Picture BirthDate capital temperature population Oviedo Asturias Fernando Alonso wd:Q14317
- 17. RDF graphs arecomposable RDF helps information integration 36^^xsd:integer wdt:P2076 wd:Q10514 wd:Q3934 wdt:P19 wdt:P1376 "1981-07-29"^^xsd:date 220020^^xsd:integer wdt:P1082 wdt:P18 wdt:P569 ...jpg wd:Q14317 :alice :bob :carol schema:birthPlace schema:birthPlace schema:knows schema:knows Alice Cooper Schema:name Robert Smith schema:nameschema:knows Carol King schema:name
- 18. RDF data model Graph= set of statements (triples) Predicates (arcs) = URIs Subjects: URIs* Objects: URIs or literals* 36^^xsd:integer wdt:P2076 wd:Q10514 wd:Q3934 wdt:P19 wdt:P1376 "1981-07-29"^^xsd:date 220020^^xsd:integer wdt:P1082 wdt:P18 wdt:P569 ...jpg wd:Q14317 *Exception: blank nodes (next slide)
- 19. RDF data model:Blank nodes A statement about something Example: "Alice knows someone who knows Bob" :alice schema:knows :bob schema:knows :alice schema:knows _:x ; _:x schema:knows :bob . Notation (in Turtle) :alice schema:knows [ schema:knows :bob ] . x ( :alice :knows x x :knows :bob )
- 20. RDF data model:Literals :bob schema:name "Robert"^^xsd:string ; schema:age "18"^^xsd:integer ; schema:birthDate "2010-04-12"^^xsd:date . :bob schema:name "Robert" ; schema:age 18 ; schema:birthDate "2010-04-12"^^xsd:date . Objects can also be literals Literals contain a lexical form and a datatype Common datatypes: XML Schema primitive datatypes If not specified, a literal has type xsd:string :bob schema:name "2010-04-12"^^xsd:date18"Robert Smith" schema:age schema:birthDate
- 21. RDF data model:Language tagged strings String literals can be qualified by a language tag They have datatype rdfs:langString :spain rdfs:label "Spain"@en ; rdfs:label "España"@es . :Spain "España"@es"Spain"@en rdfs:label rdfs:label
- 22. ...and that's all Yes,the RDF Data model is simple
- 23.
- 24. SELECT ?name ?birthDate?picture WHERE { ?person wdt:P19 wd:Q14317 ; rdfs:label ?name ; wdt:P569 ?birthDate ; wdt:P18 ?picture . FILTER (Lang(?name) = 'es') } SPARQL SPARQL = Simple Protocol and RDF Query Language Similar to SQL, but for RDF Example: People born in Oviedo wdt:P19 "1981-07-29"^^xsd:date wdt:P18 wdt:P569 Oviedo wd:Q14317 "Fernando Alonso"@en rdfs:label ?person ?birthPlace?name ?picture wdt:P19 wdt:P18wdt:P569 wd:Q14317 rdfs:label wd:Q10514 wdt:P19 ...
- 25. Shared entities andvocabularies URIs as global identifiers allow to reuse them Lots of vocabularies: domain specific or general purpose Examples: schema.org: properties that major browsers can recognize Linked Open Vocabularies
- 26. Inference and ontologies Somevocabularies define properties that can infer new information RDF Schema: Classes, subclasses, etc. OWL: Ontologies using description logics Trade-off between expressiveness and complexity rdf:type :Student :alice :Person rdfs:subClassOf :HumanBeing owl:sameAs rdf:type rdf:type
- 27. RDF, the goodparts... RDF as an integration language RDF as a lingua franca for semantic web and linked data RDF flexibility & integration Data can be adapted to multiple environments Open and reusable data by default RDF for knowledge representation RDF data stores & SPARQL
- 28. RDF, the otherparts Consuming & producing RDF Multiple syntaxes: Turtle, RDF/XML, JSON-LD, ... Embedding RDF in HTML Describing and validating RDF content Producer Consumer
- 29. Why describe &validate RDF? For producers Developers can understand the contents they are going to produce Ensure they produce the expected structure Advertise and document the structure Generate interfaces For consumers Understand the contents Verify the structure before processing it Query generation & optimization Producer Consumer Shapes
- 30. Similar technologies Technology Schema RelationalDatabases DDL XML DTD, XML Schema, RelaxNG, Schematron Json Json Schema RDF ? Fill that gap
- 31. Understanding the problem Identifyingthe shape of graphs... Shapes can describe the form of a node (node constraint) ...and the number of possible arcs incoming/outgoing from a node ...and the possible values associated with those arcs :alice schema:name "Alice"; schema:knows :bob, :carol . IRI schema:name string 1 schema:knows IRI 0, 1,... RDF Node Shape RDF Node that represents a User <UserShape> IRI { schema:name xsd:string ; schema:knows IRI * } ShEx
- 32. Understanding the problem Repeatedproperties The same property can be used for different purposes in the same data Example: A product must have 2 codes with different structure :product schema:productID "isbn:123-456-789"; schema:productID "code456" . A practical example from FHIR See: http://hl7-fhir.github.io/observation-example-bloodpressure.ttl.html
- 33. Understanding the problem Shapes≠ types Nodes in RDF graphs can have 0, 1 or many rdf:type declarations A type can be used in multiple contexts, e.g. foaf:Person Nodes are not necessarily annotated with discriminating types Nodes with type :Person can represent friends, students, patients,... Different meanings and different structure depending on context Specific validation constraints for different contexts
- 34. Understanding the problem RDFvalidation ≠ ontology definition ≠ instance data Ontologies are usually focused on domain entities RDF validation is focused on RDF graph features (lower level) Ontology Constraints RDF Validation Instance data Different levels :alice schema:name "Alice"; schema:knows :bob . <User> IRI { schema:name xsd:string ; schema:knows IRI } schema:knows a owl:ObjectProperty ; rdfs:domain schema:Person ; rdfs:range schema:Person . A user must have only two properties: schema:name of value xsd:string schema:knows with an IRI value
- 35. Why not usingSPARQL to validate? Pros: Expressive Ubiquitous Cons Expressive Idiomatic many ways to encode the same constraint ASK {{ SELECT ?Person { ?Person schema:name ?o . } GROUP BY ?Person HAVING (COUNT(*)=1) } { SELECT ?Person { ?Person schema:name ?o . FILTER ( isLiteral(?o) && datatype(?o) = xsd:string ) } GROUP BY ?Person HAVING (COUNT(*)=1) } { SELECT ?Person (COUNT(*) AS ?c1) { ?Person schema:gender ?o . } GROUP BY ?Person HAVING (COUNT(*)=1)} { SELECT ?Person (COUNT(*) AS ?c2) { ?S schema:gender ?o . FILTER ((?o = schema:Female || ?o = schema:Male)) } GROUP BY ?Person HAVING (COUNT(*)=1)} FILTER (?c1 = ?c2) } Example: Define SPARQL query to check: There must be one schema:name which must be a xsd:string, and one schema:gender which must be schema:Male or schema:Female
- 36. Previous/other approaches SPIN, byTopQuadrant http://spinrdf.org/ SPARQL templates, Influenced SHACL Stardog ICV: http://docs.stardog.com/icv/icv-specification.html OWL with UNA and CWA OSLC resource shapes: https://www.w3.org/Submission/shapes/ Vocabulary for RDF validation Dublin Core Application profiles (K. Coyle, T. Baker) http://dublincore.org/documents/dc-dsp/ RDF Data Descriptions (Fischer et al) http://ceur-ws.org/Vol-1330/paper-33.pdf RDFUnit (D. Kontokostas) http://aksw.org/Projects/RDFUnit.html ...
- 37. ShEx and SHACL 2013RDF Validation Workshop Conclusions of the workshop: There is a need of a higher level, concise language for RDF Validation ShEx initially proposed (v 1.0) 2014 W3c Data Shapes WG chartered 2017 SHACL accepted as W3C recommendation 2017 ShEx 2.0 released as Community group draft 2018 ShEx adopted by Wikidata
- 38. Short intro toShEx ShEx (Shape Expressions Language) Concise and human-readable language for RDF validation & description Syntax similar to SPARQL, Turtle Semantics inspired by regular expressions & RelaxNG 2 syntaxes: Compact and RDF/JSON-LD Official info: http://shex.io Semantics: http://shex.io/shex-semantics/, primer: http://shex.io/shex-primer
- 39. ShEx implementations andplaygrounds Libraries: shex.js: Javascript SHaclEX: Scala (Jena/RDF4j) PyShEx: Python shex-java: Java Ruby-ShEx: Ruby Online demos & playgrounds ShEx-simple RDFShape ShEx-Java ShExValidata
- 40. Simple example Nodes conformingto <User> shape must: • Be IRIs • Have exactly one schema:name with a value of type xsd:string • Have zero or more schema:knows whose values conform to <User> prefix schema: <http://schema.org/> prefix xsd: <http://www.w3.org/2001/XMLSchema#> <User> IRI { schema:name xsd:string ; schema:knows @<User> * } Prefix declarations as in Turtle/SPARQL
- 41. RDF Validation usingShEx :alice schema:name "Alice" ; schema:knows :alice . :bob schema:knows :alice ; schema:name "Robert". :carol schema:name "Carol", "Carole" . :dave schema:name 234 . :emily foaf:name "Emily" . :frank schema:name "Frank" ; schema:email <mailto:[email protected]> ; schema:knows :alice, :bob . :grace schema:name "Grace" ; schema:knows :alice, _:1 . _:1 schema:name "Unknown" . Try it (RDFShape): https://goo.gl/97bYdv Try it (ShExDemo):https://goo.gl/Y8hBsW Schema Data <User> IRI { schema:name xsd:string ; schema:knows @<User> * } :alice@<User>, :bob @<User>, :carol@<User>, :dave @<User>, :emily@<User>, :frank@<User>, :grace@<User> Shape map
- 42. Validation process :alice@:User, :bob@:User,:carol@:User ShEx Validator Result shape map :User { schema:name xsd:string ; schema:knows @:User * } ShEx Schema :alice schema:name "Alice" ; schema:knows :alice . :bob schema:knows :alice ; schema:name "Robert". :carol schema:name "Carol", "Carole" . RDF data Shape map :alice@:User, :bob@:User, :carol@!:User Input: RDF data, ShEx schema, Shape map Output: Result shape map
- 43. Example with moreShEx features :AdultPerson EXTRA rdf:type { rdf:type [ schema:Person ] ; :name xsd:string ; :age MinInclusive 18 ; :gender [:Male :Female] OR xsd:string ; :address @:Address ? ; :worksFor @:Company + ; } :Address CLOSED { :addressLine xsd:string {1,3} ; :postalCode /[0-9]{5}/ ; :state @:State ; :city xsd:string } :Company { :name xsd:string ; :state @:State ; :employee @:AdultPerson * ; } :State /[A-Z]{2}/ :alice rdf:type :Student, schema:Person ; :name "Alice" ; :age 20 ; :gender :Male ; :address [ :addressLine "Bancroft Way" ; :city "Berkeley" ; :postalCode "55123" ; :state "CA" ] ; :worksFor [ :name "Company" ; :state "CA" ; :employee :alice ] . Try it: https://tinyurl.com/yd5hp9z4
- 44. More info aboutShEx See: ShEx by Example (slides): https://figshare.com/articles/ShExByExample_pptx/6291464 ShEx chapter from Validating RDF data book: http://book.validatingrdf.com/bookHtml010.html
- 45. Short intro toSHACL W3C recommendation: https://www.w3.org/TR/shacl/ (July 2017) RDF vocabulary 2 parts: SHACL-Core, SHACL-SPARQL
- 46. SHACL implementations Name PartsLanguage - Library Comments Topbraid SHACL API SHACL Core, SPARQL Java (Jena) Used by TopBraid composer SHACL playground SHACL Core Javascript (rdflib.js) http://shacl.org/playground/ SHACLEX SHACL Core Scala (Jena, RDF4j) http://rdfshape.weso.es pySHACL SHACL Core, SPARQL Python (rdflib) https://github.com/RDFLib/pySHACL Corese SHACL SHACL Core, SPARQL Java (STTL) http://wimmics.inria.fr/corese RDFUnit SHACL Core, SPARQL Java (Jena) https://github.com/AKSW/RDFUnit
- 47. Basic example Try it.RDFShape https://goo.gl/T1uuzv prefix : <http://example.org/> prefix sh: <http://www.w3.org/ns/shacl#> prefix xsd: <http://www.w3.org/2001/XMLSchema#> prefix schema: <http://schema.org/> :UserShape a sh:NodeShape ; sh:targetNode :alice, :bob, :carol ; sh:nodeKind sh:IRI ; sh:property :hasName, :hasEmail . :hasName sh:path schema:name ; sh:minCount 1; sh:maxCount 1; sh:datatype xsd:string . :hasEmail sh:path schema:email ; sh:minCount 1; sh:maxCount 1; sh:nodeKind sh:IRI . :alice schema:name "Alice Cooper" ; schema:email <mailto:[email protected]> . :bob schema:firstName "Bob" ; schema:email <mailto:[email protected]> . :carol schema:name "Carol" ; schema:email "[email protected]" . Shapes graph Data graph
- 48. Same example withblank nodes Try it. RDFShape https://goo.gl/ukY5vq prefix : <http://example.org/> prefix sh: <http://www.w3.org/ns/shacl#> prefix xsd: <http://www.w3.org/2001/XMLSchema#> prefix schema: <http://schema.org/> :UserShape a sh:NodeShape ; sh:targetNode :alice, :bob, :carol ; sh:nodeKind sh:IRI ; sh:property [ sh:path schema:name ; sh:minCount 1; sh:maxCount 1; sh:datatype xsd:string ; ] ; sh:property [ sh:path schema:email ; sh:minCount 1; sh:maxCount 1; sh:nodeKind sh:IRI ; ] . :alice schema:name "Alice Cooper" ; schema:email <mailto:[email protected]> . :bob schema:firstName "Bob" ; schema:email <mailto:[email protected]> . :carol schema:name "Carol" ; schema:email "[email protected]" . Shapes graph Data graph
- 49. Some definitions aboutSHACL Shape: collection of targets and constraints components Targets: specify which nodes in the data graph must conform to a shape Constraint components: Determine how to validate a node Shape target declarations constraint components :UserShape a sh:NodeShape ; sh:targetNode :alice, :bob, :carol ; sh:nodeKind sh:IRI ; sh:property :hasName, :hasEmail . :hasName sh:path schema:name ; sh:minCount 1; sh:maxCount 1; sh:datatype xsd:string . . . .
- 50. Validation Report The outputof the validation process is a list of violation errors No errors RDF conforms to shapes graph [ a sh:ValidationReport ; sh:conforms false ; sh:result [ a sh:ValidationResult ; sh:focusNode :bob ; sh:message "MinCount violation. Expected 1, obtained: 0" ; sh:resultPath schema:name ; sh:resultSeverity sh:Violation ; sh:sourceConstraintComponent sh:MinCountConstraintComponent ; sh:sourceShape :hasName ] ; ... [ a sh:ValidationReport ; sh:conforms true ].
- 51. SHACL processor SHACL Processor Validation report :UserShapea sh:NodeShape ; sh:targetNode :alice, :bob, :carol ; sh:nodeKind sh:IRI ; sh:property :hasName, :hasEmail . :hasName sh:path schema:name ; sh:minCount 1; sh:maxCount 1; sh:datatype xsd:string . . . . Shapes graph :alice schema:name "Alice Cooper" ; schema:email <mailto:[email protected]>. :bob schema:name "Bob" ; schema:email <mailto:[email protected]> . :carol schema:name "Carol" ; schema:email <mailto:[email protected]> . Data Graph [ a sh:ValidationReport ; sh:conforms true ].
- 52. SHACL Core built-inconstraint components Type Constraints Cardinality minCount, maxCount Types of values class, datatype, nodeKind Values node, in, hasValue, property Range of values minInclusive, maxInclusive minExclusive, maxExclusive String based minLength, maxLength, pattern Language based languageIn, uniqueLang Logical constraints not, and, or, xone Closed shapes closed, ignoredProperties Property pair constraints equals, disjoint, lessThan, lessThanOrEquals Non-validating constraints name, description, order, group Qualified shapes qualifiedValueShape, qualifiedValueShapesDisjoint qualifiedMinCount, qualifiedMaxCount
- 53. Longer example :AdultPerson EXTRAa { a [ schema:Person ] ; :name xsd:string ; :age MinInclusive 18 ; :gender [:Male :Female] OR xsd:string ; :address @:Address ? ; :worksFor @:Company + ; } :Address CLOSED { :addressLine xsd:string {1,3} ; :postalCode /[0-9]{5}/ ; :state @:State ; :city xsd:string } :Company { :name xsd:string ; :state @:State ; :employee @:AdultPerson * ; } :State /[A-Z]{2}/ :AdultPerson a sh:NodeShape ; sh:property [ sh:path rdf:type ; sh:qualifiedValueShape [ sh:hasValue schema:Person ]; sh:qualifiedMinCount 1 ; sh:qualifiedMaxCount 1 ; ] ; sh:targetNode :alice ; sh:property [ sh:path :name ; sh:minCount 1; sh:maxCount 1; sh:datatype xsd:string ; ] ; sh:property [ sh:path :gender ; sh:minCount 1; sh:maxCount 1; sh:in (:Male :Female); ] ; sh:property [ sh:path :age ; sh:maxCount 1; sh:minInclusive 18 ] ; sh:property [ sh:path :address ; sh:node :Address ; sh:minCount 1 ; sh:maxCount 1 ] ; sh:property [ sh:path :worksFor ; sh:node :Company ; sh:minCount 1 ; sh:maxCount 1 ]. :Address a sh:NodeShape ; sh:closed true ; sh:property [ sh:path :addressLine; sh:datatype xsd:string ; sh:minCount 1 ; sh:maxCount 3 ] ; sh:property [ sh:path :postalCode ; sh:pattern "[0-9]{5}" ; sh:minCount 1 ; sh:maxCount 3 ] ; sh:property [ sh:path :city ; sh:datatype xsd:string ; sh:minCount 1 ; sh:maxCount 1 ] ; sh:property [ sh:path :state ; sh:node :State ; ] . :Company a sh:NodeShape ; sh:property [ sh:path :name ; sh:datatype xsd:string ] ; sh:property [ sh:path :state ; sh:node :State ] ; sh:property [ sh:path :employee ; sh:node :AdultPerson ; ] ;. :State a sh:NodeShape ; sh:pattern "[A-Z]{2}" . In ShEx In SHACL Its recursive!!! (not well defined SHACL) Implementation dependent feature Try it: https://tinyurl.com/ycl3mkzr
- 54. More info aboutSHACL SHACL by example (slides): https://figshare.com/articles/SHACL_by_example/6449645 SHACL chapter at Validating RDF data book http://book.validatingrdf.com/bookHtml011.html
- 55. Some challenges andperspectives Theoretical foundations of ShEx/SHACL Inference shapes from data Validation Usability RDF Stream validation Schema ecosystems Wikidata Solid
- 56. Theoretical foundations ofShEx/SHACL Conversion between ShEx and SHACL SHaclEX library converts subsets of both Challenges Recursion and negation Performance and algorithmic complexity Detect useful subsets of the languages Convert to SPARQL Schema/data mapping Shapes Shapes ShEx SHACL
- 57. Inference of Shapesfrom Data Useful use case in practice Knowledge Graph summarization Some prototypes: ShExer, RDFShape, ShapeArchitect Try it with RDFShape: https://tinyurl.com/y8pjcbyf Shape Expression generated for wd:Q51613194 Shapes RDF data infer
- 58. Validation usability Learning fromusers Early adopters: WebIndex, HL7 FHIR, Eclipse Lyo, GenWiki,… Improve error information/visualization/navigation/repairing Authoring/visualization tools Propose annotation sets UI generation Error reporting/suggestion (SHOULD/MUST/…) Shapes
- 59. RDF Stream validation Validationof RDF streams Challenges: Incremental validation Named graphs Addition/removal of triples Sensor Stream RDF data Shapes Validator Stream Validation results
- 60. Schema ecosystems: Wikidata InMay, 2019, Wikidata announced ShEx adoption New namespace for schemas Example: https://www.wikidata.org/wiki/EntitySchema:E2 It opens lots of opportunities/challenges Schema evolution and comparison
- 61. Schema ecosystems: Solidproject SOLID (SOcial Linked Data): Promoted by Tim Berners-Lee Goal: Re-decentralize the Web Separate data from apps Give users more control about their data Internally using linked data & RDF Shapes needed for interoperability See: https://ruben.verborgh.org/blog/2019/06/17/shaping-linked-data-apps/ Data pod Shape A Shape C Shape B App 1 App 2 App 3
- 62. Conclusions RDF as abasis for knowledge graphs Explicit schemas can help improve data quality 2 languages proposed: ShEx/SHACL Lots of new challenges and opportunities
- 63.
Editor's Notes
- #54 ShEx: 20 lines of code SHACL: 60 lines of code