Tutorial: Ontology Development

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"What's up folks." Today we are going to create a movie ontology for a client of your Acme company.

Step 1: Ontology Plug-in

Ontologies are encapsulated in OSGi bundles. In eclipse we develop them as equinox plug-ins. An ontology bundle is a package that contains the sources (graph/*.pgraph), a compiled graph file (graph.tg), and Java resource files (src/ and bin/).

Open a New Plug-in Project wizard:

  • Open Plug-in Development Perspective
  • Select File >> New >> Other
  • Select Plug-in Development >> Plug-in Project

A New Plug-in Project wizard will open.

  1. Our organization is Acme Software ltd and from there is our plug-in name derived, com.acme.movie.ontology. Insert that as project name. Next >
  2. In the following page you should know that this plugin does not contribute to UI, does not need activator or isn't a rich client application. Next >
  3. Select a template Plug-in with a Simantics Ontology. Finish

Setup Graph Building Nature

First, Make sure you have installed Ontology Graph Compiler to your Eclipse. Next, add Graph builder into the project nature.

  • "com.acme.movie.ontology"' >> Context Menu >> Configure >> Add graph compilation

Graph nature.png

Also create directory called graphs, and there a file Movie.pgraph.

Configure MANIFEST.MF

Your ontology well depend on Layer0, so open META-INF/MANIFEST.MF in a editor and add org.simantics.layer0 to plug-in dependencies.

Also, you are going to

  • Export package com.acme.movie.ontology

Your MANIFEST.MF should look like this. 

Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Ontology
Bundle-SymbolicName: com.acme.movie.ontology
Bundle-Version: 1.0.0.qualifier
Bundle-Vendor: ACME
Bundle-RequiredExecutionEnvironment: JavaSE-1.6
Require-Bundle: org.simantics.layer0;bundle-version="1.0.0"
Export-Package: com.acme.ontology

Developing the ontology

Open Movie.pgraph and start editing.

As you are using Layer0 concepts, it is a good idea to capture its namespace: 

 L0 = <http://www.simantics.org/Layer0-1.0>

Your acme company has a namespace which is used . You are creating a new one so it must be stated. 

 <http://com.acme> : L0.Library
     @L0.new

The ontology has a representing resource, an instance of L0.Ontology. Don't forget to add stub-compiler metadata L0.HasResourceClass. 

 Movie = <http://com.acme/Movie-1.0> : L0.Ontology
     L0.HasResourceClass "com.acme.ontology.Movie"
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