1. Chapter 22 Object-Oriented Systems Analysis and Design and UML
Kendall and Kendall
Fifth Edition

2. Copyright © 2002 by Prentice Hall, Inc.
Major Topics
Object-oriented programming concepts
Object-oriented terminology
Five-layer model
CRC Cards
Unified Modeling Language
Use case and other UML diagrams
Relationships
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

3. Object-Oriented Overview
Object-oriented techniques work well in situations where complicated systems are undergoing continuous maintenance, adaptation, and design
There are two ways to model object-oriented systems
Coad and Yourdon methodology
The Unified Modeling Language
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

4. Object-Oriented Programming
Six ideas characterize object-oriented programming:
An object, which represents a real-world thing or event
A class, or group of related objects
Messages, sent between objects
Encapsulation, only an object makes changes through its own behavior
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

5. Object-Oriented Programming
Six ideas characterize object-oriented programming (continued):
Inheritance, a new class created from another class
Polymorphism, meaning that a derived class behavior may be different from the base class
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

6. Copyright © 2002 by Prentice Hall, Inc.
Terminology
Class refers to a template for a group of individual objects with common attributes and common behavior
The difference between an Object and a Class is that the class defines shared attributes and behaviors of objects
An object is an instance or occurrence of a class
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

7. Copyright © 2002 by Prentice Hall, Inc.
Terminology
Another name for property is attribute
Another name for method is operation
Interface means the behavior of a class or component that is noticeable from outside the class or component
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

8. Copyright © 2002 by Prentice Hall, Inc.
Encapsulation
Encapsulation changes the manner in which data is updated by programs because data can only be changed via the services that encapsulate the data
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

9. Copyright © 2002 by Prentice Hall, Inc.
Inheritance
The two types of classes are involved in any inheritance relationship are the base class and the derived class
Multiple inheritance means there will be multiple occurrences of the base type of class in the inheritance relationship
Polymorphism only occurs where there is inheritance
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

10. Copyright © 2002 by Prentice Hall, Inc.
Five-Layer Model
Object oriented analysis and design is based on a five-layer model:
Class/object layer notes the classes and objects
Structure layer captures various structures of classes and objects, such as one-to-many relationships and inheritance
Attribute layer details the attributes of classes
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

11. Copyright © 2002 by Prentice Hall, Inc.
Five-Layer Model
Five-layer model, continued
Service layer notes messages and object behaviors
Subject layer divides the design into implementation units or team assignments
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

12. Five General Types of Objects
There are five general types of objects:
Tangible things
Roles
Incidents
Interactions
Specifications details
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

13. Criteria to Determine Need for a New Class of Objects
Criteria to determine whether a new class of objects is justified
There is a need to remember the object
There is a need for certain behaviors of the object
An object has multiple attributes
A class has more than one object instantiation
Unless it is a base class
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

14. Criteria to Determine Need for a New Class of Objects
Criteria, continued
Attributes have a meaningful value for each object in a class
Services behave the same for every object in a class
Objects implement requirements that are derived from the problem setting
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

15. Criteria to Determine Need for a New Class of Objects
Criteria, continued
Objects do not duplicate attributes and services that could be derived from other objects in the system
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

16. Basic Types of Structures
There are two basic types of structures that might be imposed on classes and objects:
Generalization-Specialization structure (Gen-Spec), which connect class-to-class
Whole-Part structure which are collections of different objects that compose another whole object
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

17. Copyright © 2002 by Prentice Hall, Inc.
Instance Connections
Instance connections are references between objects such as associations or relationships indicated by a single line between objects using the same cardinality notation as Whole-Part structures
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

18. Copyright © 2002 by Prentice Hall, Inc.
Methods
Services (or methods or procedures) must be analyzed. Activities are
Object state analysis, showing changes of state
Service specification: creating, storing, retrieving, connecting, accessing, and deleting objects
Message specification, consisting of control and data flow
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

19. Major Components of Object-Oriented Design Activities
Object-oriented design activities are grouped into four major components:
The problem domain component
The human interface component
The data management component
The task management component
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

20. Problem Domain Component
The problem domain component consists of
Reuse design
Implementation structures
Language accommodation
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

21. Copyright © 2002 by Prentice Hall, Inc.
CRC Cards
Class, responsibilities, and collaborators (CRC) cards are used to represent the responsibilities of classes and the interaction between the classes
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

22. Copyright © 2002 by Prentice Hall, Inc.
Creating CRC Cards
Analysts create CRC cards by
Finding all the nouns and verbs in a problem statement
Create scenarios that are actually walkthroughs of system functions
Identify and refine responsibilities into smaller and smaller tasks, if possible
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

23. Copyright © 2002 by Prentice Hall, Inc.
Creating CRC Cards
Creating CRC cards, continued
The group determines how tasks are fulfilled by objects or interacting with other things
Responsibilities evolve into methods or operations
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

24. The Unified Modeling Language (UML)
UML (Unified Modeling Language) is the result of a collaboration of individual object-oriented methods that has been adopted as a standard for modeling object-oriented systems
It differs from the Coad and Yourdon OOA-OOD in the way that it breaks down objects and their relationships
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

25. The Unified Modeling Language (UML)
UML has three categories:
Things, the objects
Relationships, the glue that holds things together
Diagrams, categorized as either structure or behavioral
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

26. Copyright © 2002 by Prentice Hall, Inc.
Use Case
A use case describes 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
Copyright © 2002 by Prentice Hall, Inc.

27. Copyright © 2002 by Prentice Hall, Inc.
Kinds of Use Cases
There are two kinds of use cases:
Primary, the standard flow of events within a system that describe a standard system behavior
Use case scenarios that describe variations of the primary use case
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

28. 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
Copyright © 2002 by Prentice Hall, Inc.

29. Steps for Creating a Use Case Model
Creating a use case model, 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
Move to UML diagramming techniques to complete the systems analysis and design
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

30. Two General Groupings of Things
There are two general groupings of things in UML:
Structural things that define the conceptual and physical structures of an O-O system and are described by nouns
Behavioral things, the verbs of a UML model that represent the behavior of the system and the states of the system before, during, and after the behaviors occur
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

31. Categories of Structural Things
There are seven categories of structural things
The first five are conceptual or logical
The last two are physical in nature
Component
Node
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

32. Categories of Structural Things
Seven categories of structural things:
Classes, which have properties or attributes and methods or operations
Interfaces, the behavior of a class or component of a system that is noticeable from outside the class or component
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

33. Categories of Structural Things
Seven categories, continued
Collaborations, which describe the interactions of two or more things in a system that perform a behavior that is more than any one of the things can do alone
Use cases, which describe a series of actions that demonstrate a distinct behavior of the system and its interactions with the actors
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

34. Categories of Structural Things
Seven categories, continued
Control or active classes
A control class can initiate and control an independent flow of activity within the system
Components, which are a physical part of a system that represents the services and interfaces implemented by the elements contained within that component, including software code
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

35. Categories of Structural Things
Seven categories, continued
Nodes, which represent a piece of hardware on which your system executes
Components are physically deployed on nodes
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

36. Copyright © 2002 by Prentice Hall, Inc.
Behavioral Things
Behavioral things consist of
Interactions, or messages sent between a set of objects within the system to perform a specific task
State machine, a series of states that an object goes through in response to actions within the system
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

37. Copyright © 2002 by Prentice Hall, Inc.
Packages
Packages are groups of things
They can be physical subsystems
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

38. Types of Relationships
There are two types of relationships that hold things together:
Structural
Behavioral
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

39. Types of Structural Relationships
There are four types of structural relationships:
Dependencies, where one thing affects another thing that uses it
Aggregations, which show how the whole object is composed of the sum of its parts
Associations that describe structural connections between things
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

40. Types of Structural Relationships
Four types of structural relationships, continued
Generalizations, which describe a relationship between a general kind of thing and a more specific kind of thing, used for modeling class inheritance and specialization
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

41. Types of Active Behavioral Relationships
There are four active behavioral relationships:
Communicates is used to connect an actor to a use case
Includes describes the situation where a use case contains a behavior that is common to more than one use case
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

42. Types of Active Behavioral Relationships
Types of active behavioral relationships, continued
Extends describes the situation where one use case possesses the behavior that allows the new use case to handle a variation or exception
Generalizes implies that one thing is more typical than the other thing
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

43. UML Structural Diagrams
UML structural diagrams include
Class diagrams used to model the static structural design of a system
Object diagrams portray the state of class instances and their relationships at a point in time
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

44. UML Structural Diagrams
UML structural diagrams, continued
Component diagrams show an overview of the system architecture
A deployment diagram illustrates the physical implementation of the system, including the hardware
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

45. Copyright © 2002 by Prentice Hall, Inc.
Behavioral Diagrams
Behavioral diagrams describe the interaction between people and a use case
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

46. Copyright © 2002 by Prentice Hall, Inc.
Behavioral Diagrams
Behavioral Diagrams include
Use case diagrams, showing the actors and the use cases
Sequence diagrams that depict a succession of interactions between object instances over time and they show the processing described in use case scenarios
Activity diagrams show the flow of activities within a process
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

47. Copyright © 2002 by Prentice Hall, Inc.
Behavioral Diagrams
Behavioral Diagrams, continued
Collaboration diagrams illustrate a sequence of object interactions showing the organization of the objects during the interactions
State chart diagrams show the states of an object and the events and conditions that trigger a transition from one state to another
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.

48. Copyright © 2002 by Prentice Hall, Inc.
Steps Used in UML
The steps used in UML are
Define the use case model
Define the object model
Continue UML diagramming to model the system during the systems analysis phase
Begin system design by refining UML diagrams and using them to derive classes and their properties and methods
Kendall & Kendall
Copyright © 2002 by Prentice Hall, Inc.