Analysis and Design with UML: Discovering ClassesIntroductionTopics for DiscussionCRC Card MethodCRC CardCRC Card ExampleCRC Card: UserInterfaceCRC Card: KeypadCRC Card: TemperatureClass DiscoveryClassesDiscovering Classes (Alternative)ExamplesSummary01/14/19 B.Ramamurthy 1Analysis and Design with UML: Discovering ClassesBina Ramamurthy01/14/19 B.Ramamurthy 2IntroductionPurpose of this part is to transform the requirement analysis represented by the use-case diagram(s) to design diagrams using static analysis.The result of this phase is UML class diagrams consisting of classes and relationship among them.We will study techniques to discover classes and the UML notations for representing class diagrams.01/14/19 B.Ramamurthy 3Topics for DiscussionClasses, Responsibility, Collaboration (CRC) method for discovering classes and assigning responsibility.Class-based Analysis and Design: UML notations, class diagrams.Case Studies.01/14/19 B.Ramamurthy 4CRC Card MethodAlthough proponents of the object paradigm often say that identifying objects is a simple and intuitive process, a number of noted experts admit that this is not always true! …The solution is to use the CRC process to determine the classes necessary to the system as part of the design process for the application. CRC (classes, responsibility, and collaboration) cards can be used to visualize and test different class-based models during the design phase. It is a proven technique used and advocated by leading methodologists.01/14/19 B.Ramamurthy 5CRC CardClass NameResponsibilitiesCollaborations01/14/19 B.Ramamurthy 6CRC Card ExampleWeather Station1. Select 24hr/Current2. Set Date Time3. Display Current1. Temp(T)2. Wind (W)3. Pressure (P)4. Humidity (H)4. Display 24hours1. Hi/Lo for (TWPH)5. Display Trends in TWPH6. CalibrateResponsibilitiesCollaborationsUser Interface(UI)DateTimeTempWindPressureHumidityCalibrator01/14/19 B.Ramamurthy 7CRC Card: UserInterfaceUserInterface1. Input date2. Input time3. Input selection4. Display dataResponsibilitiesCollaboratorsKeypadDisplayTempWindPressureHumidity01/14/19 B.Ramamurthy 8CRC Card: KeypadKeypadResponsibilities1. Store date2. Store time3. Store selectionCollaboratorsDateTimeSelection01/14/19 B.Ramamurthy 9CRC Card: TemperatureTemperatureResponsibilities1. Measure and Record temperature2. Determine and record Hi/Lo3. Determine trendCollaborationsT.DeviceStatDataBaseDateTime01/14/19 B.Ramamurthy 10Class Discovery The entries in the collaborations column are possible classes or non-software entities.In this case these are: UserInterface, Display, Tempertaure, Wind, Pressure, Humidity, StatDataBase, Selection, Date, Time, Keypad, Callibrator.The responsibility of designing one or more of these classes can be assigned to the members of the group who participated in this discovery process.On to relations among classes and class diagrams.01/14/19 B.Ramamurthy 11ClassesOO paradigm supports the view that a system is made up of objects interacting by message passing.Classes represent collection of objects of the same type.An object is an instance of a class.A class is defined by its properties and its behaviors.A class diagram describes the static view of a system in terms of classes and relationships among the classes.01/14/19 B.Ramamurthy 12Discovering Classes (Alternative)Underline the nouns in a problem statement.Using the problem context and general knowledge about the problem domain decide on the important nouns.Design and implement classes to represent the nouns.Underline the verbs. Verbs related to a class may represent the behavior of the class.01/14/19 B.Ramamurthy 13ExamplesDrawing package: Design a user interface for drawing various shapes: circle, square, rectangle.Football scores: Keep track of football score.General purpose counter: To keep of track of count for various applications.Library: Books, different categories of books, details of student borrower, library personnel.01/14/19 B.Ramamurthy 14SummaryWe looked at Class Diagrams which is very important part of UML Model, perhaps the only model used in many design representation.We also looked at two methods for class discovery(/analysis): CRC Card Method and Nouns-Verbs.Class diagrams directly represent the implementation (code) classes and the relationship among
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