Section 7.15-(Optional) Software Engineering Case Study: Identifying Class Operations in the ATM System-identifies the operations, or services, of our classes. We extract from the requirements document the verbs and verb phrases that specify the operations for each class. We then modify the class diagram of Section 3.10 to include each operation with its associated class. At this point in the case study, we will have gathered all information possible from the requirements document. However, as future chapters introduce such topics as inheritance, we will modify our classes and diagrams.
Section 8.14-(Optional) Software Engineering Case Study: Collaboration Among Objects in the ATM System-provides a "rough sketch" of the model for our ATM system. In this section, we see how it works. We investigate the behavior of the simulation by discussing collaborations-messages that objects send to each other to communicate. The class operations that we discovered in Section 6.9 turn out to be the collaborations among the objects in our system. We determine the collaborations, then collect them into a communication diagram-the UML diagram for modeling collaborations. This diagram reveals which objects collaborate and when. We present a communication diagram of the collaborations among objects to perform an ATM balance inquiry. We then present the UML sequence diagram for modeling interactions in a system. This diagram emphasizes the chronological ordering of messages. A sequence diagram models how objects in the system interact to carry out withdrawal and deposit transactions.
Section 9.17-(Optional) Software Engineering Case Study: Starting to Program the Classes of the ATM System-takes a break from designing the behavior of our system. We begin the implementation process to emphasize the material discussed in Chapter 8. Using the UML class diagram of Section 3.10 and the attributes and operations discussed in Section 4.11 and Section 6.9, we show how to implement a class in C# from a design. We do not implement all classes-because we have not completed the design process. Working from our UML diagrams, we create code for the Withdrawal class.
Section 11.9-(Optional) Software Engineering Case Study: Incorporating Inheritance and Polymorphism into the ATM System-continues our discussion of object-oriented programming. We consider inheritance-classes sharing common characteristics may inherit attributes and operations from a "base" class. In this section, we investigate how our ATM system can benefit from using inheritance. We document our discoveries in a class diagram that models inheritance relationships-the UML refers to these relationships as generalizations. We modify the class diagram of Section 3.10 by using inheritance to group classes with similar characteristics. This section concludes the design of the model portion of our simulation. We implement this model as C# code in Appendix J.
Appendix J-ATM Case Study Code-The majority of the case study involved designing the model (i.e., the data and logic) of the ATM system. In this appendix, we implement that model in C#. Using all the UML diagrams we created, we present the C# classes necessary to implement the model. We apply the concepts of object-oriented design with the UML and object-oriented programming in C# that you learned in the chapters. By the end of this appendix, you will have completed the design and implementation of a real-world system, and should now feel confident tackling larger systems, such as those that professional software engineers build.