For browsing through a loaded application in the KB we use the GraphBrowser Utility.
The GraphBrowser (described in section 4.2.3) allows you display arbitrary objects from the current application. We display the object Employee by choosing the Browse Graphical function from the menubar and defining Employee as the object to be browsed in the dialogue window provided. After the GraphBrowser window shows up, we select the Employee object and choose the Show Subclasses option from the GraphBrowser menu. The displayed graph is now expanded (figure 4.9). Notice, that the selected object, the node Employee, is marked with small rectangles at each corner.
Figure 4.9: The resulting graph after expanding the node Employee with subclasses.
Now we expand the node Manager, a subclass of Employee, by choosing the GraphBrowser menu item Show Instances. The resulting graph is shown in figure 4.10.
Figure 4.10: The resulting graph after expanding with the instances of Manager.
Now the selected object is the node Manager. The instances of Manager are shown as grey rectangles, because they are also instances of the system class Token. The nodes Manager, Salesman, Employee etc. are shown as ovals, since these nodes are instances of the system class SimpleClass (see for a full description of graphical object semantics: Appendix B).
One can move nodes and links by selecting a node or a link and then holding down the left mouse button while moving the cursor to a different position. When the button is released the selected object will be located at the current position and the related links are redisplayed.
We select the node Employee again and choose the menu item Any. An interaction window appears querying for the orientation (coming_out_of, going_into, or simply c and g) and the label to be considered for the expansion of the displayed graph. We specify c as orientation and `*instanceof' as label, to see all the classes, where Employee is an instance of. To see the attributes of the class Employee we choose the menu option Show Attributes (the node Employee should still be selected). Figure 4.11 shows the resulting graph. Some of the nodes have been manually moved to present a clearer picture. \
Figure 4.11: The graph after expanding it with the superclasses and the attributes of the class Employee.