Challenges and applications of RDF shapes

Challenges and applications of
RDF Shapes

About me…
HTML version: http://book.validatingrdf.com
Examples: https://github.com/labra/validatingRDFBookExamples

RDF Data Model
<http://example.com/alice> <http://schema.org/enrolledIn> <http://example.com/cs101> .
N-Triples representation
:alice :cs101
subject
schema:enrolledIn
predicate
object
http://example.com/alice http://example.com/cs101
http://schema.org/enrolledIn

RDF Graph
Basic statement = a simple triple

RDF Graph
…we can add more statements
:alice
23
Circled nodes are IRIs
Yellow boxes are literals

RDF Graph
…and automatically merged
RDF helps information integration

RDF syntaxes
<http://example.org/alice> <http://example.org/name> "Alice" .
<http://example.org/alice> <http://example.org/age> "23"^^<http://www.w3.org/2001/XMLSchema#integer> .
<http://example.org/alice> <http://example.org/enrolledIn> <http://example.org/cs101> .
<http://example.org/alice> <http://example.org/knows> <http://example.org/carol> .
<http://example.org/alice> <http://example.org/birthPlace> <http://example.org/Oviedo> .
<http://example.org/bob> <http://example.org/name> "Robert" .
<http://example.org/bob> <http://example.org/age> "None" .
<http://example.org/bob> <http://example.org/birthPlace> <http://example.org/Oviedo> .
<http://example.org/bob> <http://example.org/enrolledIn> <http://example.org/cs102> .
<http://example.org/carol> <http://example.org/name> "Carol" .
<http://example.org/carol> <http://example.org/enrolledIn> <http://example.org/cs101> .
<http://example.org/cs101> <http://example.org/subject> "Programming" .
<http://example.org/cs101> <http://example.org/students> <http://example.org/alice> .
<http://example.org/cs101> <http://example.org/students> <http://example.org/carol> .
<http://example.org/cs102> <http://example.org/subject> "Algebra" .
<http://example.org/cs102> <http://example.org/students> <http://example.org/bob> .

Turtle Syntax
;
,
prefix : <http://example.org/>
:alice :name "Alice" ;
:age 23 ;
:enrolledIn :cs101 ;
:knows :carol ;
:birthPlace :Oviedo .
:carol :name "Carol" ;
:enrolledIn :cs101 .
:cs101 :students :alice , :carol ;
:subject "Programming" .
:bob :name "Robert" ;
:age "None" ;
:enrolledIn :cs102 ;
:birthPlace :Oviedo .
:cs102 :students :bob ;
:subject "Algebra" . Try it: https://goo.gl/pK3Csh

Literals
:bob :name "Robert"^^xsd:string ;
:age "18"^^xsd:integer ;
:birthDate "2010-04-12"^^xsd:date .
:bob :name "Robert" ;
:age 18 ;
:birthDate "2010-04-12"^^xsd:date .

Bob knows someone whose age is 23
=
 x(:bob :knows x  x :age 23)
Blank nodes
:bob :knows _:1 .
_:1 :age 23 .
:bob :knows [
:age 23
] .
or

Language tagged strings
rdfs:langString
:spain rdfs:label "Spain"@en ;
rdfs:label "España"@es .

RDF, the other parts
Producer Consumer

Why describe & validate RDF?
Producer Consumer
Shapes

Similar technologies
Technology Schema
Relational
Databases
DDL
XML DTD, XML Schema,
RelaxNG, Schematron
Json Json Schema
RDF ?
Fill that gap

Shapes vs Ontology
Ontology
Shapes
RDF Validation
Constraints
Instance data
Different levels
:alice rdf:type foaf:Person, schema:Person ;
:hasParent :bob .
:bob rdf:type foaf:Person ;
:gender :male .
:Person { rdf:type [ foaf:Person ] ;
:hasParent @:Person AND { :gender :male } ? ;
:hasParent @:Person AND { :gender :female } ?
}
:Person  rdf:type(foaf:Person) 
= 1 :hasParent :Male 
= 1 :hasParent :Female

Why not using SPARQL to validate?
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

Short intro to ShEx
http://shex.io
http://shex.io/shex-semantics/ http://shex.io/shex-primer

ShEx implementations and
playgrounds
shex.js
SHaclEX
PyShEx
shex-java
Ruby-ShEx
Online demos &
playgrounds
ShEx-simple
RDFShape
ShEx-Java
ShExValidata
Wikishape

Simple example
<User>
schema:name xsd:string
schema:knows
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

RDF Validation using ShEx
: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:frank@example.org> ;
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:knows @<User> *
}
:alice@<User>,
:bob @<User>,
:carol@<User>,
:dave @<User>,
:emily@<User>,
:frank@<User>,
:grace@<User>
Shape map








Validation process
:alice@:User, :bob@:User, :carol@:User
ShEx
Validator
Result shape map
:User {
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

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

SHACL
https://www.w3.org/TR/shacl/ (July 2017)

SHACL implementations
Name Parts Language -
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/pySHAC
L
Corese SHACL SHACL Core, SPARQL Java (STTL) http://wimmics.inria.fr/corese
RDFUnit SHACL Core, SPARQL Java (Jena) https://github.com/AKSW/RDFUnit

Basic example
prefix sh: <http://www.w3.org/ns/shacl#>
: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: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


Try it. RDFShape https://goo.gl/ukY5vq

Same example with blank nodes
prefix sh: <http://www.w3.org/ns/shacl#>
sh:property [
sh:path schema:name ;
sh:minCount 1; sh:maxCount 1;
sh:datatype xsd:string ;
] ;
sh:property [
sh:path schema:email ;
] .
schema:email <mailto:alice@mail.org> .
:bob schema:firstName "Bob" ;
schema:email "carol@mail.org" .
Shapes graph
Data graph


Try it. RDFShape https://goo.gl/ukY5vq

Some definitions about SHACL
Shape
target declarations
constraint components
:hasEmail .
sh:minCount 1;
sh:maxCount 1;
. . .

Validation Report
[ 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
] ;
...
sh:conforms true
].

SHACL processor
SHACL
Processor
Validation report
:hasEmail .
sh:minCount 1;
sh:maxCount 1;
. . .
Shapes
graph
schema:email <mailto:alice@mail.org>.
:bob schema:name "Bob" ;
schema:email <mailto:carol@mail.org> .
Data
Graph
sh:conforms true
].

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:property [ sh:path :gender ;
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 ;
].
:Address a sh:NodeShape ;
sh:closed true ;
sh:property [ sh:path :addressLine;
] ;
sh:property [ sh:path :postalCode ;
sh:pattern "[0-9]{5}" ;
] ;
sh:property [ sh:path :city ;
] ;
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

ShEx and SHACL compared
ShEx SHACL
Underlying philosophy Structure definition Constraint checking
Syntax Compact syntax + RDF RDF
Notion of shape Only structure Structure + target decls.
Default cardinalities {1,1} {0,*}
Shapes and inference No SHACL specific entailment
Recursion Part of the language Undefined
Repeated properties Part of the language Conjunction by default
Requires qualifiedValueShapes
Property paths Nested shapes SPARQL like
Property pair comparisons Unsupported in current version Part of the language
Extension mechanism Semantic actions SHACL-SPARQL
Validation triggering Query shape map Target declarations
Result of validation Result shape map Validation report

Shapes applications and challenges

Theoretical foundations of ShEx/SHACL
Shapes Shapes
ShEx SHACL

Generating Shapes from Data
Try it with RDFShape:
https://tinyurl.com/y8pjcbyf
Shape Expression
generated for
wd:Q51613194
Shapes
RDF data
infer

RDF Stream validation
Sensor
Stream
RDF
data
Shapes
Validator
Stream
Validation
results

Ontological infrastructure
https://github.com/geneontology/go-shapes/
Control version
system (git)
Continuous
Integration
server
Ontological
infrastructure
Ontology
engineer
Triple
Store
Endpoint
SPARQL
Ontology
publication
system
Shapes library
Ontologies
Test data

Programming with shapes
Semantic architecture Ontological infrastructure
UML
Diagrams
Shapes
library
Domain
model Syncrhonization

Schema ecosystems: Wikidata
https://www.wikidata.org/wiki/EntitySchema:E2

Schema ecosystems: Solid project
Data
pod
Shape
A
Shape
C
Shape
B
App
1
App
2
App
3
"...I just can’t stop thinking about shapes.", Ruben Verborgh
https://ruben.verborgh.org/blog/2019/06/17/shaping-linked-data-apps/

Shapes ecosystem @ WESO
Producer Consumer
Shapes

Shapes ecosystem @ WESO
http://github.com/weso

Dependency map between
repositories

Data validation
RDF validation
Generic schemas: ShEx/SHACL
Converter ShEx  SHACL

RDF data validation with Shapes
https://typelevel.org/cats/

Edit/create shapes
Shapes editor
Syntax highlighting, autocomplete, etc.

Shapes playgrounds
http://rdfshape.weso.es
http://wikishape.weso.es
https://tinyurl.com/shqrban

Extract/generate shapes
http://shexer.weso.es/

Shapes programming
Code generation
from Shapes
ShEx  POJO (Java)
Shape
A
Shape
C
Shape
B

Challenges and applications of RDF shapes

Challenges and applications of RDF shapes

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