Diagram Panel

The Diagram Panel can be used to visualize and edit ontologies in UML-like diagrams. It is accessed by clicking on the Diagram tab at the bottom of the Resource Editor.

What the diagrams visualize

Each class is shown as a rectangle. Inside the rectangle you will see all the properties the class is in the domain of - either based on rdfs:domain statements, or on local OWL restrictions or SPIN constraints such as spl:Attributes. Classes shown in the diagram can be moved around and rearranged.

Thick black arrows depict subclass relationships. In the diagram below ProductVendor is a subclass of Organization. Thinner black arrows show property relationships that have been defined using rdfs:domain and rdfs:range statements. ProductVendor is in the range of the isProductOf property. Product is in the domain of the property.

When a subclass relationship has been inferred, it is shown as a thick blue arrow.

Mouse over the class rectangle to see arrows at both ends - incoming and outgoing. Yellow arrows indicate that there are connections to or from the class. Click on the arrow to expand the diagram, revealing the neighbors of the current class.

Thin blue arrows show relationships defined using rdfs:subClassOf local restrictions. Mouse over the arrow to see the restriction axiom.

Local restrictions defined using owl:equivalentClass are shown as small gray-shaded rectangles. In the diagram below Actor has been defined as equivalent class of tqec:performs some tqec:Activity.

Red arrows show disjoint classes.

Note that you can drag and drop classes from elsewhere (e.g. from the Classes View) into the class diagram to add them to the display. The system will in this case add edges to all classes that are already in the diagram.

When you open a diagram for the first time, it will contain the currently selected class with all its superclasses, plus the direct neighbors of the selected class. By default, each time you open a diagram or change the selected resource, the diagram will be reset to this layout. If you have expanded a diagram to a state that you want to keep for your records, you can use the snapshot feature, as shown below. All snapshots in your project will be saved together with your ontology, into a file ending with .diagrams.

The icons at the top of the panel provide the following options:

• Take a snapshot of the current layout
• Delete the currently selected snapshot
• Re-layout all
• Undo - use this button to close a previously expanded connection
• Delete the currently selected nodes from the diagram (not from the model)
• Save - use this button to save the diagram as JPEG or BMP file
• Print the current graph (a printer dialog should open)
• Go to Diagram Preferences
• Zoom in and out

How to edit diagrams

The palette on the left of the diagram shows various tools that can be used to switch between edit modes:

• By default, you are in Select mode that allows you to select and drag around the nodes in the diagram.
• Select Create class mode and then click on an empty area of the diagram. This opens up a dialog in which you can enter a name for the new class. The new class will show up at the location where you clicked on the diagram and is then ready to be connected to the other classes. Another way of creating new classes is through a right-click on the head area of a class node in the diagram, and then select Create subclass of....
• In Add subClassOf mode, click on the class that shall become the subclass (typically displayed underneath the superclass). The class will become yellow until you click on a suitable superclass to establish the new relationship.
• In Add association mode, you can create new object properties that link two selected classes. Click on the class where the association is supposed to start. The class will become yellow. This will become the rdfs:domain of the new property. Then click on the class that shall become the rdfs:range of the new property. The resulting dialog allows you to enter a name for the new property. If you have activated the corresponding preference, the system will create an owl:allValuesFrom restriction instead of range and domain statements.

In order to delete a subClassOf or association, right click on the connection and select Delete in the popup menu. Note that deleting an association will also delete all triples that use this property.

A double-click on a class opens a form to edit the details of the class. A double-click on an "attribute" property opens a form to edit the details of that property. Right-click on an "attribute" property and select Delete to completely delete it.

If you right-click on an attribute property or an association connection, the resulting popup menu will include items to set the cardinality (using owl:Restrictions) to either 0..1, 1..1, 0..n or 1..n.

If you move the mouse over a class box, a small button will appear in the lower right corner. This button can be used to create a new (datatype) property that will have the class as its rdfs:domain. In the resulting dialog, you can enter a name for the property and also specify a rdfs:range such as xsd:boolean, xsd:float, xsd:integer or xsd:string.

Note that the system will by default not remember the layout of your diagram. For example if you have added a new class to a diagram and then move to another class (wiping out the current diagram) and then come back to the class where you started editing with, then the diagram will only contain the default diagram for that class. Use the snapshots feature described above to keep diagrams exactly like you have edited them.