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G2GML

The Graph To Graph Mapping Language (G2GML) is a language for mapping RDF graphs to property graphs.

Overview

  • The mapping is described with a combination of RDF graph patterns and property graph patterns.
  • RDF graph patterns are written in WHERE clause syntax of SPARQL, while the property graph patterns are written in MATCH clause syntax of Cypher.

Structure of G2GML

<prefixes>

<property graph patterns>           <-- Cypher MATCH clause syntax
    <semantic graph patterns>       <-- SPARQL WHERE clause syntax

...

Basic Examples

  • RDF resource > PG node
  • RDF datatype property > PG node property
  • RDF object property > PG edge

RDF resource > PG node

Input: mini-01.ttl

@prefix : <http://example.org/> .
:person1 a :Person .

Mapping: mini-01.g2g

PREFIX : <http://example.org/>
(p:person)                          <-- PG node is defined
    ?p a :Person .

Output: mini-01.pg

"http://example.org/person1" :person

RDF datatype property > PG node property

Input: mini-02.ttl

@prefix : <http://example.org/> .
:person1 a :Person .
:person1 :age 30 .

Mapping: mini-02.g2g

PREFIX : <http://example.org/>
(p:person {age:a})                 <-- PG node property is defined
    ?p a :Person .
    ?p :age ?a .

Output: mini-02.pg

"http://example.org/person1" :person age:30

RDF object property > PG edge

Input: mini-03.ttl

@prefix : <http://example.org/> .
:person1 a :Person .
:person2 a :Person .
:person1 :follows :person2 .

Mapping: mini-03.g2g

PREFIX : <http://example.org/>
(p:person)
    ?p a :Person .
(p1:person)-[:follows]->(p2:person)       <-- PG edge is defined
    ?p1 :follows ?p2 .

Output: mini-03.pg

"http://example.org/person1" :person
"http://example.org/person2" :person
"http://example.org/person1" -> "http://example.org/person2" :follows

RDF resource > PG edge

Input: mini-04.ttl

@prefix : <http://example.org/> .
:person1 a :Person .
:person2 a :Person .
[] a :Follow ;
   :follower :person1 ;
   :followed :person2 .

Mapping: mini-04.g2g

PREFIX : <http://example.org/>
(p:person)
    ?p a :Person .
(p1:person)-[:follows]->(p2:person)       <-- PG edge is defined
    ?f :follower ?p1 ;
       :followed ?p2 .

Output: mini-04.pg

"http://example.org/person1" :person
"http://example.org/person2" :person
"http://example.org/person1" "http://example.org/person2" :follows

RDF datatype property > PG edge property

Input: mini-05.ttl

@prefix : <http://example.org/> .
:person1 a :Person .
:person2 a :Person .
[] a :Follow ;
   :follower :person1 ;
   :followed :person2 ;
   :since 2017 .

Mapping: mini-05.g2g

PREFIX : <http://example.org/>
(p:person)
    ?p a :Person .
(p1:person)-[:follows {since:s}]->(p2:person)    <-- PG edge is defined
    ?f :follower ?p1 ;
       :followed ?p2 ;
       :since ?s .

Output: mini-05.pg

"http://example.org/person1" :person
"http://example.org/person2" :person
"http://example.org/person1" "http://example.org/person2" :follows since:2017

Actual Example

musician.g2g

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX schema: <http://schema.org/>
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
PREFIX dbpedia-prop: <http://dbpedia.org/property/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

# Node mappings
(mus:musician {vis_label:nam, born:dat, hometown:twn, page_length:len})
    ?mus rdf:type foaf:Person, dbpedia-owl:MusicalArtist .
    ?mus rdfs:label ?nam .
    FILTER(lang(?nam) = "en") .
    OPTIONAL { ?mus dbpedia-prop:born ?dat }
    OPTIONAL { ?mus dbpedia-owl:hometown / rdfs:label ?twn. FILTER(lang(?twn) = "en"). }
    OPTIONAL { ?mus dbpedia-owl:wikiPageLength ?len }

# Edge mappings
(mus1:musician)-[:same_group {label:nam, hometown:twn, page_length:len}]->(mus2:musician)
    ?grp a schema:MusicGroup.
    { ?grp dbpedia-owl:bandMember ?mus1 , ?mus2. } UNION
    { ?grp dbpedia-owl:formerBandMember ?mus1 , ?mus2. }
    FILTER(?mus1 != ?mus2)
    OPTIONAL { ?grp rdfs:label ?nam. FILTER(lang(?nam) = "en")}
    OPTIONAL { ?grp dbpedia-owl:hometown / rdfs:label ?twn. FILTER(lang(?twn) = "en"). }
    OPTIONAL { ?grp dbpedia-owl:wikiPageLength ?len }

(mus1:musician)-[:influenced]->(mus2:musician)
    ?mus1 dbpedia-owl:influenced ?mus2 .