Hello World: Rational Software Architect V7

Create a class diagram

Class diagrams are the blueprints of your system. You can use class diagrams to model the objects that make up the system, to display the relationships between the objects, and to describe what those objects do and the services they provide.

You'll design the simple phone book application using the Model-View-Controller (MVC) architecture pattern, as shown in Figure 7. (See Resources to learn about MVC.) For the phone book application you'll need to create the following three classes:

• PhoneBookModel manages the phone book entries and captures the state of the application. Whenever the state is changed, it notifies PhoneBookView, which should then refresh the user interface based on the state of the application.
• PhoneBookView manages the graphical or textual interface to the user based on the state of the application, and notifies PhoneBookController when an input is received.
• PhoneBookController controls the operation of the entire application. It changes the model state of the application and updates the data model based on user input.

The purpose of this exercise is to show you how to use Rational Software Architect when designing an application. The design itself is not the focus. You may proceed with a different design if you prefer.

Now create a class diagram that reflects the design in Figure 7.

1. In Rational Software Architect's Model Explorer view, right-click Phone Book UML Model and select Add Diagram > Class Diagram.
2. Enter Class Diagram as the name of the generated diagram to replace the default name ClassDiagram1.
3. Select Class in the Palette, then click anywhere in the diagram to create a class. Name it PhoneBookModel.
4. Right-click the created class PhoneBookModel and select Add UML > Operation to create an operation for this class. Name it setState.
5. Similarly, create the rest of the elements as shown in Table 2. The operation names are chosen without assumptions regarding the programming language used.

6. Next you'll create some associations to relate these three classes. As shown in Figure 8, click the arrow that appears next to Association from the Palette and select Directed Association.
   
   Figure 8. Selecting Directed Association from the Palette
   
   
   
7. Draw the association relationship line from the class PhoneBookController to PhoneBookModel (the order is important) to initiate a directed association relationship between these two classes. A directed association relationship means the first class is aware of the second one, but not the other way around.
8. Name this directed association relationship controllerHasModel.
9. Now that you've done it once, create a couple more relationships. This time create association relationships without direction, which means the two connected classes are mutually aware of each other:
   • Create an association relationship between the class PhoneBookModel and PhoneBookView and name it modelView.
   • Create an association relationship between the class PhoneBookView and PhoneBookController and name it viewController.
10. The complete class diagram should look similar to Figure 9. Select Ctrl-S to save the diagram.
    
    Figure 9. A complete class diagram for the phone book application
    
    
    

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Table of contents

• Before you start
• Introduction
• How does Rational Software Architect fit into SOA?
• What is UML?
• Design a phone book application
• Create a use case diagram
• Create a class diagram
• Create a sequence diagram
• Publishing the design
• Transformation and true round-trip engineering
• Complete the implementation
• Summary
• Download
• Resources
• About the author

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