graphml/Entity Relationship to OWL

This python script takes as input a graphml file, produced with the yEd graph editor, that contains 'Entity with Attributes' nodes and labelled edges. It translates it into an OWL ontology in RDF/Turtle format.

The translation rules are:

• every 'Entity with Attributes' node with label C is transformed into a OWL class C

• an edge with label 'subClassOf' from C to D ---> an axiom

     :C rdfs:subClassOf :D
  

• an edge with label P from C to D ---> an axiom

     :C rdfs:subClassOf [a owl:Restriction ; owl:onProperty :P ; owl:allValuesFrom :D]
  

• an edge with a label of the form 'P min 1' from C to D ---> an axiom

     :C rdfs:subClassOf [a owl:Restriction ; owl:onProperty :P ; owl:someValuesFrom :D]
  

• the second label (in the attribute box of the node) is considered as a comment. It yields

    :C rdfs:comment Text-of-the-attribute-box
  

Usage:

$ python graphml2owl.py graphmlfile

The OWL ontology is written into graphmlfile_owl.ttl

!! requires python 3.7 (uses type annotations)

graphml2rdf: a Graphml to RDF translator

This xsl stylesheets transforms a graphml file produced by yEd using the Entity-Relationship elements into an RDF graph.

The graph must be composed of Entity with Attributes or Entity nodes (from the Entity-Relationship palette in yEd). For Entity with Attributes nodes

• the Entity field (top) must contain a class name (or empty)
• the Attributes field (bottom) must contain an instance name (or empty)

See the file ex-1.graphml for an example.

Entity nodes represent literal values. The node label must contain the value without quotes. Literal types are not supportent yet.

See the file ex-lit.graphml for an example.

To run the transformation tool

1. Download graphml2rdf.xsl and saxon9he.jar (the Saxon xml library)
2. Execute the following command:

java -jar saxon9he.jar -xsl:graphml2rdf.xsl graphml-file > rdf-file

The output file is an RDF/XML file. It can be directly uploaded into a triple store.

Transformation principles

The instance names generate "local" URIs, based on the input file name. Thus several generated RDF files can be uploaded to a repository without mixing up the instance names. The class names generate "global" URIs, independent of the source file. So the same class name appearing in different graphml graphs will generate the same URI. In this sense class names are global.