Session 22

Question 1

What are the 3 basic principles of object orientation

Answer 1

Abstraction
Hierarchy
Polymorphism

Question 2

Whats abstraction

Answer 2

Any model that includes the most important, essential, or distinguishing
aspects of something; while suppressing or ignoring less important detail

Question 3

Whats hierarchy

Answer 3

Any ordering of abstractions into a tree like structure

Question 4

Whats polymorphism

Answer 4

Many forms
The same named operation may be completed differently for diff objects/classes

Question 5

What are the strengths of Object Orientation

Answer 5

• A single paradigm
  –> across analysis, design, and implementation
  –> amongs users, analysts, designers, and implementers
• Facilitates software reuse
• Models more closely reflect the real world

Question 6

What does use case modeling focus on

Answer 6

A diagram that shows a set of use cases and actors and their relationships
What a system does or should do,
NOT how the system delivers those functions

Question 7

Whats an actor

Answer 7

Anything interacting with the system
Not part of the system
Represents a human, machine, another system
Represents roles, not a person

Question 8

Whats a use case

Answer 8

Sequences of actions a system performs
Represents interaction of actors with the system –> performed ad initiated by actors

Question 9

What are three types of organization of use cases

Answer 9

Generalization
Include
Extend

Question 10

What generalization

Answer 10

Child use case inherits behavior & meaning of parent use case
Solid arrow

Question 11

Whats include

Answer 11

Useful when you have sub-functions in common
Helps avoid redundancy by letting use cases share sub-functions
The sub-function must be implemented

Question 12

Whats extend

Answer 12

The extend relationship models optional system behavior
You separate optional behavior from mandatory behavior

Question 13

What are the steps to developing a use case

Answer 13

1. Identify the actors that interact with the system
2. Organize actors by identifying roles
3. For each actor, consider the behavior that each expects or requires the system to provide
4. Name these common behaviors as use cases
5. Consider the exceptional ways in which each actor interacts with the system
6. Organize use cases by applying include and extend relationships to factor common behavior and distinguish exceptional behavior