Software Engineering

1. Software Engineering - Mr. Ahmad Al-Ghoul

2. Learning Objectives • Describe Unified Modeling Language (UML) tools and techniques, including class diagrams, sequence diagrams, state transition diagrams, and activity diagrams • Explain how to organize an object model

3. Object-Oriented analysis and design using UML • Class Diagram • A class is a collection of objects with common structure, common behaviour, common relationships, and common semantics. • A class diagram represents a detailed view of single use case • Show the classes that participate in the use case • Document the relationship among the classes • Class diagram is a logical model, which evolves into a physical model and finally becomes a functioning information system

4. Object-Oriented analysis and design using UML • Class Diagram • A class is drawn as a rectangle with the class name at the top • Classes should be named using the vocabulary of the domain • Naming standards should be created • The class’s attributes • The class’s methods • Lines show relationship between classes and have labels identifying the action that relates the two classes • When you construct the class diagram, the first step is to review the use case and identify the classes that participate in the underlying business transaction

5. Object-Oriented analysis and design using UML • Cardinality describes how instances of one class relate to instance's of anther class Examples of UML notations that indicate the nature of the relationship between instances of one class and instances of another class. [1]

6. Object-Oriented analysis and design using UML • Class diagram for a sales order use case (attributes and methods omitted for clarity). • Notice that the sales office has one sales manager who can have anywhere from zero to many sales rep. • Each sales rep can have anywhere from zero to many customers, but each customer has only one sales rep [1]

7. Object-Oriented analysis and design using UML • The use case diagram presents an outside view of the system • Interaction diagrams describe how use cases are realized as interactions among societies of objects • Sequence diagrams, state transition diagrams, and activity diagrams are dynamic modeling tools that can help a systems analyst understand how objects behave and interact with the system.

8. Object-Oriented analysis and design using UML • Sequence Diagrams • A sequence diagram is a dynamic model of a use case • Sequence diagrams show classes interactions arranged in a time sequence • A sequence diagram graphically documents the use case by showing the classes, the messages, and the timing of the messages • specified by the flow of events.

9. Object-Oriented analysis and design using UML • Sequence diagrams include symbols that represent • Classes • Lifelines • Messages • Focuses

10. Object-Oriented analysis and design using UML • Classes • A class is identified by a rectangle with the name inside. • Classes that send or receive messages are shown at the top of the sequence diagram • Lifelines • A lifeline is identified by a dashed line • The lifeline represents the time during which the object above it is able to interact with the other objects in the use case • An X marks the end of the lifeline

11. Object-Oriented analysis and design using UML • Messages • A message is identified by a line showing direction that runs between two objects • The label shows the name of the message and can include additional information about the content • Focuses • A focus is identified vertical shape that covers the lifeline • The focus indicates when an object sends or receives a message

12. Object-Oriented analysis and design using UML The sequence diagram for the ADD NEW STUDENT use case. [1]

13. Object-Oriented analysis and design using UML • State Transition Diagrams • A state transition diagram shows how an object changes from one state to another, depending on events that affect the object • A state transition diagram shows • The life history of a given object • The events that cause a transition from one state to another • The actions that result from a state change • In a state transition diagram, the states appear as rounded rectangles with the state names inside • The small circle to the left is the initial state • The lines show direction and describe the action or event that causes a transition from one state to anther • The circle at the right with a hollow border is the final state

14. Object-Oriented analysis and design using UML • An example of a state transition diagram for a bank account. • A bank account could be opened as NEW or EXISTING account, and eventually become a CLOSED or FORMER account • Anther possible state for a bank account could be FORZEN, if the account’s assets are legally attached [1]

15. Object-Oriented analysis and design using UML • Activity Diagrams • An activity diagram resembles a horizontal flowchart that shows the actions and events as they occur

16. Object-Oriented analysis and design using UML • Activity represented as rounded rectangles. • Activities are typically action states, it goes automatically to the next state after the action is complete. • The filled in circle represents the start • Transitions shown as arrows show how you move from activity to activity

17. Object-Oriented analysis and design using UML • An activity diagram shows the actions and events involved in withdrawing cash from an ATM machine. • Notice that the customer initiate the activity by inserting an ATM card and requesting cash [1]

18. Object-Oriented analysis and design using UML • Organizing the Object Model • Each diagram or object definition should be supported by clear, relevant documentation that can be accessed easily by anyone who reviews the object model • You should organize your use cases and use case diagrams so they can be linked to the appropriate class, state transition, sequence, and activity diagrams • Your diagrams and documentation are the foundation for the system’s design • It is much easier to repair a diagram now than to change the software later

19. Sequence Summary • A class diagram represents a a detailed view of a single use case, showing the classes that participate in the underlying business transaction, and the relationship among class instances, which is called cardinality • A sequence diagram is a dynamic model of a use case, showing the interaction among classes during a specified time period • Sequence diagram include lifelines, messages, and focuses • A state transition diagram shows how an object changes from one state to anther, depending on events that affect the object • An activity diagram resembles a horizontal flowchart that shows actions and events as they occur in a system • At the end of the object modeling process, you organize your use cases and use case diagrams and create class, sequence, state transaction, and activity diagrams

20. Sequence Summary • In this Sequence we have • Explained and described how to draw different UML diagrams including class diagrams, sequence diagrams, state transition diagrams, and activity diagrams • Defined the terms lifelines, messages, and focuses • Explained how to organize your use cases and use case diagrams and create class, sequence, state transaction, and activity diagrams

21. Reference [1] System Analysis and Design, Sixth Edition Authors: Gary B. Shelly, Thomas J. Cashman and Harry J. Rosenblatt , Publisher: SHELLY CASHMAN SEWIES. [2] system analysis and design, sixth edition Authors: Kenneth E. Kendall and Julie E. Kendall Publisher: Prentice Hall [3] Modern Systems Analysis and Design Third Edition Authors: Jeffrey A. Hoffer , Joey F. George, Joseph S. Valacich Publisher: prentice hall