Telos objects can also be edited graphically in the Graph Editor. In our example, we want to add another attribute named address to the class Employee. The attribute destination of this attribute should be a new class called Address.
First, we select the object Employee and click on the ``Create Attribute'' button in the tool bar or select ``Add Attribute'' operation from the tool bar. As we have selected the Employee object, it should be already inserted as source of the attribute. We have to type the label (address) and the destination of the attribute in the text fields (see figure 4.22). As this attribute does not belong to a specific attribute category (it is just an attribute), we do not have to specify an attribute class.
Figure 4.22: Adding an attribute to Employee
By clicking on the Ok button, the Graph Editor will create a new object for Address represented by the default graphical type (a gray box). Then, it will create the attribute link from Employee to Address with the label address. The result is shown in figure 4.23.
Now, we want to declare Address as an instance of Class. Therefore, we select Address, hold down the Shift-key and select Class. Both objects should be selected now. We click on the ``Create Instantiation'' button and a dialog as shown in figure 4.23 should appear.
Figure 4.23: Adding an instantiation link between Address and Class
As we have selected the objects in the correct way, the dialog already specifies the object we want to create (Address in Class) and we can click directly on Ok. The new instantiation link will be added to the graph.
Now, we are satisfied with our changes and want to commit them in the server. So far, the changes have been stored in an internal buffer of the Graph Editor and have not been sent to the server. We click on the ``Commit'' button in the upper right corner. The Graph Editor generates now Telos frames for the added objects and sends them to the server. If we did not make an error, all changes should be consistent and accepted by the server. This is shown by the appearing message box ``Changes committed''. If an error occurs, an error message will displayed instead.
Figure 4.24: The resulting graph after commit
If the changes were successfully told to the ConceptBase server, the Graph Editor reloads the information of every visible object. In particular, the graphical types of the objects will be updated. As the object Address is declared as instance of Class, it will get the graphical type of a class, i.e. a turquoise box. The result is shown in figure 4.24. The object Employee is shown in the detailed component view, in this case the frame representation of the object is shown. As you can see, the attribute address is now also visible in the frame representation.