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Solutions_11 - Systems Analysis and Design in a Changing...

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Systems Analysis and Design in a Changing World, Fourth Edition 11-1 Chapter 11 – The Object-Oriented Approach to Design: Use Case Realization Solutions to End-of-Chapter Material Review Questions 1. Which three models are most used to do object-oriented design? Design class diagrams, interaction diagrams, and package diagrams are the three models that are used to capture design specifications. 2. Why do we say that design is “use-case driven?” Design is done on a use case-by-use case basis. Each use case is considered and designed independently of the other use cases. 3. Four icons, or shortcuts, can be used to depict different types of classes. List the four icons, describe what each means, and show the symbol for each. An entity class is the design identifier for a problem domain class. Its icon is a circle on a flat plate. Customer A boundary class is a class that is specifically designed to live on the system s automation boundary. Its icon is a circle with a T attached to the side. OrderWindow A control class is a class that mediates between the boundary classes and the entity classes. Its icon is a circle with an attached arrow. UseCaseHandler A data access class is a class that is used to retrieve data from and send data to a database. Its icon is a circle with two extended arms.
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Systems Analysis and Design in a Changing World, Fourth Edition 11-2 OrderDBReader 4. List the elements included in a method signature. Give an example of a method signature with all elements listed correctly. A method signature shows all of the information needed to invoke (or call) the method. It shows the format of the message that must be sent, which consists of the following: method visibility, method name, type-expression, and method parameter list (incoming arguments). Example: +calculateAmount : float (startDate, endDate) 5. What is the notation used to indicate a stereotype? Show an example of a stereotyped class. The notation for a stereotype is the name of the stereotype surrounded by guillemets. «boundary» OrderWindow 6. What is meant by navigation visibility? How is it shown in UML? How is it implemented in programming code? Navigation visibility is the ability for one object to view and interact with another object. With navigation visibility, a class can access the methods of another class. In UML, navigation visibility is shown with an arrow connecting the two classes. In programming code, navigation visibility is usually implemented with a reference attribute—that is, a variable that references the visible object. 7. What does coupling mean? Why is too much coupling considered bad? Coupling is a qualitative measure of the amount of “connectedness” between classes. It is usually measured by the number of navigation visibility arrows between classes in a DCD. High coupling means that the classes are too interrelated, which can make maintaining the system very difficult. High coupling can also make it more difficult to test a system because there are so many connections that must be verified.
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