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Getting Started
Modelers typically create Ontologies during the analysis phase of an initiative when a group of Informaticians or information modelers needs to develop a shared understanding of a particular resource. The following situations are typical usages of the ontologies and the diagrams that describe them.
- Providing Human Machine readable information for the Semantic Web Applications
- Document or describe Knowledge Management Systems
Selecting the Perspective
Enterprise Architect partitions the tool's extensive features into Perspectives, which ensures that you can focus on a specific task and work with the tools you need without the distraction of other features. To work with the Ontology Definition Metamodel features you first need to select this Perspective:
<perspective name> > Information Exchange > Ontology Definition ODM
Setting the Perspective ensures that the Ontology Definition Metamodel diagrams, their tool boxes and other features of the Perspective will be available by default.
Creating Diagrams
With the ODM perspective selected, you can add a new diagram by selecting the location in the Browser window and choosing the Add Diagram option from the Context menu or from the Browser tool bar. You will be presented with the New Diagram dialog with three available ODM diagrams:
OwlDefinition - Ontology Definition Diagrams describe the ontology in terms of classes properties and relationships used to formally describe ontology concepts.
OwlFacts - Ontology Facts Diagrams describe the ontology in terms of the facts, based on the individual ontology class instances, that describe the knowledge base.
RDFDefinition - Resource Definition Diagrams describe metadata used in defining ontologies.
You can also use some of the built-in patterns available for ODM from the Model Patterns window to create a diagram of any type from the wizard. Spend some time reading the description of the pattern to understand the diagram and objects that will be inserted as part of the pattern.
Creating a Namespace
Just as a package provides a namespace for UML models an Ontology (based on a package) defines the namespace for OWL models. In a similar way, a Document, which acts as a container for elements and relationships, defines the namespace for an RDF Model. Both elements require metadata that describes important information including URIs that will act as the basis for Identifiers.
Namespace definitions are used in RDF and OWL for referencing and/or importing externally specified terms, vocabularies, or ontologies.
In the Browser window or in the open diagram, select the RDF or OWL Package to define the namespace.
Using the docked properties window locate the properties window for the RDFDocument or OWL Ontology properties.
Click on the the small triangle to the left of the namespaceDefinition property to view the tags child elements.
Click on the namespacePrefix and namespaceURI 'value' fields for the new namespace definition, and type in the appropriate new values.
More Information
This section provides useful links to other topics and resources that you might find useful when working with the Ontology Definition Metamodel tool features.
For access to the Ontology Definition Metamodel Specification managed by the Object Management Group See the following.
For information on the W3C OWL Ontology, see the following: