ONTOP - Ontology Platform

Project ONTOP eases the exposition of ontologies and other resources in Maven java web applications.

Ontologies and other resources to be exposed are placed in folder src/main/ontop, along with a RDF configuration file config.ttl that describes the different resources and their representations, using the RDF Presentation vocabulary. Then,

• maven plugin ontop-maven-plugin checks the quality of the ontologies, pre-generate their documentation, and potentially other RDF representation;
• project ontop-jersey exposes these resources on the web.

The documentation generation for the ontologies consists of two steps:

1. apply a STTL aka SPARQL-Template lowering rule to generate the documentation in the markdown syntax;
2. use the maven-site-plugin to generate the HTML documents.

In the RDF Turtle snippets below, we use the following namespace prefixes:

@prefix dc: <http://purl.org/dc/terms/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix vann: <http://purl.org/vocab/vann/> .
@prefix voaf: <http://purl.org/vocommons/voaf#> .
@prefix vs: <http://www.w3.org/2003/06/sw-vocab-status/ns#> .
@prefix foaf: <http://xmlns.com/foaf/0.1/>.
@prefix cc: <http://creativecommons.org/ns#>.
@prefix ontop: <https://w3id.org/ontop/>.
@prefix rdfp: <https://w3id.org/rdfp/>.

Exposing an ontology

The set of ontologies to be exposed can be specified in config.ttl using an instance of class ontop:OntologySet linked to a regular expression by predicate rdfp:fileSelector, or one by one using an instance of class ontop:Ontology linked to a file path by predicate rdfp:filePath.

[] a ontop:OntologySet ;
  ontop:fileSelector "[A-Za-z]+-[0-9]+\\.[0-9]+\\.ttl" .

[] a ontop:Ontology ; 
  ontop:filePath "ontop-1.0.ttl" .

Then ontop-maven-plugin will check the quality and generate documentation for all the RDF files that match the given regular expression.

Using ONTOP, the ontology editors are encouraged to use the markdown syntax when documenting the ontology (with predicate dc:description) and its resources (with predicates rdfs:comment), as this code will be properly formatted in HTML.

Let base be the maven project.url parameter specified in the POM. base is the base URI.

For now, ontop-maven-plugin checks the following items:

• The file name must be of the form NAME-MAJOR.MINOR.ttl.
• There must be a unique instance of owl:Ontology, it must also be an instance of voaf:Vocabulary. Its URI must start with base.
• The ontology must be annotated with properties dc:title, dc:description, dc:issued, dc:creator, cc:license.
• It must have a vann:preferredNamespacePrefix, a vann:preferredNamespaceUri that starts with base.
• It must have a owl:versionIRI that starts with base.
• It must have a owl:versionInfo that starts with v{MAJOR}.{MINOR}.
• Other resources that this ontology defines should be linked to the ontology with property rdfs:isDefinedBy.

Generated report file target/ontop.ttl lists the problems in every analyzed ontology document.

Then, the ontology document is accessible at its version IRI as HTML, Turtle, or RDF/XML. The canonical locations of the representations are versionIRI.html for the HTML, versionIRI.ttl for the Turtle, versionIRI.rdf for the RDF/XML. If it has the highest version in the ontology series, then it is also accessible at its IRI as HTML, Turtle, or RDF/XML. It is also accessible in HTML at ontologyIRI.html, but the canonical location of the representation is still versionIRI.html.

Finally, if the ontology IRI is exactly base, then the latest version is accessible at index, index.html, index.ttl, and index.rdf.

Exposing a RDF graph

An RDF graph to be exposes must be specified in config.ttl using an instance of class rdfp:Graph linked to a file path by predicate rdfp:filePath.

<example/description> a rdfp:Graph ; 
  ontop:filePath "example-description.ttl" .

then file with local path "example-description.ttl" will be accessible as Turtle or RDF/XML at <example/description>. The canonical locations of the representations are <example/description.ttl> for the Turtle, and <example/description.rdf> for the RDF/XML.

Exposing other resources

Other resources with one/several representations to be exposed must be specified in config.ttl using an instance of class rdfp:Resource linked to one/several instances of rdfp:Representation using predicate rdfp:representedBy. Then these representations specify the media type of the representation, and the local file.

<example/description> a rdfp:Resource ; 
  rdfp:representedBy [ ontop:filePath "description.html" ; rdfp:mediaType "text/html" ] ;
  rdfp:representedBy [ ontop:filePath "description.txt" ;  rdfp:mediaType "text/plain" ] .

Then, in addition to the previously mentioned Turtle and RDF/XML representations for resource <example/description>, two additional representations are now exposed: an HTML and a plain text representations. The canonical locations of the representations are <example/description.html> for the HTML, and <example/description.txt> for the plain text.

Using ONTOP

Binaries, sources and documentation for ontop are available for download at Maven Central. To use it in your Maven project, add the ontop plugin, the maven site plugin, and the ontop dependency to your Maven project file ( *.pom file), like is done in this project.

The following web applications use ONTOP to document and expose ontologies and other resources:

• SEAS - Smart Energy Aware Systems ontologies ;
• Lindt - Linked Datatypes;
• RDFP - RDF Presentation project;
• PEP - Process Execution Platform project;
• STN - the Socio-technical networks ontologies;
• CNR Smart Charging Provider, a SEAS pilot platform.

Contact

[email protected]

http://maxime-lefrancois.info/