Chapter 18 Object-Oriented Systems Analysis and Design Using UML Kendall & Kendall Sixth Edition

Object-Oriented Overview Object-oriented (o-o) techniques work well in situations where complicated systems are undergoing continuous maintenance, adaptation, and design. The Unified Modeling Language (UML) is an industry standard for modeling object-oriented systems. Reusability is the main goal. Kendall & Kendall © 2005 Pearson Prentice Hall

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Commonly Used UML Diagrams The most commonly used UML diagrams are: Use case diagram, describing how the system is used. The starting point for UML modeling. Use case (not a diagram). Activity diagram. Each use case may create one activity diagram. Kendall & Kendall © 2005 Pearson Prentice Hall

Commonly Used UML Diagrams The most commonly used UML diagrams (continued): Sequence diagram, showing the sequence of activities and class relationships. Each use case may create one or more sequence diagrams. A collaboration diagram is an alternative to a sequence diagram. Kendall & Kendall © 2005 Pearson Prentice Hall

Commonly Used UML Diagrams The most commonly used UML diagrams (continued): Class diagram, showing classes and relationships. Sequence diagrams and CRC cards are used to determine classes. Statechart diagram. Each class may create a statechart diagram, useful for determining class methods. Kendall & Kendall © 2005 Pearson Prentice Hall

© 2005 Pearson Prentice Hall Use Case Diagram A use (yoos) case describes what the system does, not how it does the work. The use case model reflects the view of the system of the user outside of the system. Symbols are: Actor, a stick figure. Use case, an oval. Connecting lines. Kendall & Kendall © 2005 Pearson Prentice Hall

© 2005 Pearson Prentice Hall Actors Represent role played by one or more users Exist outside of the system May be a person, another system, a device, such as a keyboard or Web connection Can initiate an instance of a use case May interact with one or more use cases and a use case may involve one or more actors Kendall & Kendall © 2005 Pearson Prentice Hall

© 2005 Pearson Prentice Hall Use Case Consists of three things: An actor (user) that initiates an event. An event that triggers a use case. The use case that performs the actions triggered by the event. Kendall & Kendall © 2005 Pearson Prentice Hall

© 2005 Pearson Prentice Hall Use Case (Continued) Better to create fewer use cases 20 use cases for a large system 50 use cases would be the maximum for a large system Can nest use cases, if needed Kendall & Kendall © 2005 Pearson Prentice Hall

Use Case Relationships Communicates Connect an actor to a use case Includes Use case contains a behavior that is common to more than one use case. The common use case is included in other use cases. Dotted arrow points toward common use case. Kendall & Kendall © 2005 Pearson Prentice Hall

Use Case Relationships (Continued) Extends A different use case handles variations or exceptions from the basic use case. Arrow goes from extended to basic use case. Generalizes One thing is more general than another thing. Arrow points to the general thing. Kendall & Kendall © 2005 Pearson Prentice Hall

Use Case Relationships Kendall & Kendall © 2005 Pearson Prentice Hall

Steps for Creating a Use Case Model The steps required to create a use case model are: Review the business specifications and identify the actors within the problem domain. Identify the high-level events and develop the primary use cases that describe the events and how actors initiate them. Kendall & Kendall © 2005 Pearson Prentice Hall

Steps for Creating a Use Case Model The steps required to create a use case model are (continued): Review each primary use case to determine possible variations of flow through the use case. Develop the use case documents for all primary use cases and all important use case scenarios. Kendall & Kendall © 2005 Pearson Prentice Hall

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