L6 - Object Design

Question 1

Adapter Pattern

Answer 1

Connects incompatible components (wrapper: bank COBOL) + inheritance followed by delegation

Question 2

Object Model Restructuring

Answer 2

improve understandability and extensibility

Question 3

Black Box Reuse

Answer 3

Composition & Aggregation: New class offers aggregated functionality of existing classes.

Question 4

Object Design focuses on …

Answer 4

reuse and specification.

Question 5

Characteristics of Structural Patterns and Examples

Answer 5

Reduce Coupling & Extensibility & Encapsulation: Adapter/Bridge/Composite/Façade/Proxy

Question 6

Specialization

Answer 6

superclass discovered first

Question 7

Commercial-Off-The-Shelf Development fills design gap with …

Answer 7

standard components (‘buy’)

Question 8

OOSE

Answer 8

Object-Oriented Software Engineering: System Design + Object Design + Implementation

Question 9

Implementation Inheritance

Answer 9

Subclassing from implemented class that nearly has the same functionality (Stack/List: super bad). Reuse implemented functionality of superclass. PRO: Easy BUT: Bad Change Management / No Information Hiding

Question 10

Types of Frameworks

Answer 10

infrastructure & middleware & whitebox & blackbox frameworks

Question 11

Bridge Pattern

Answer 11

Delay design decision until runtime & provide multiple implementations under same interface & Bridge between Abstraction and Implementation: Delegation followed by inheritance

Question 12

Strict Inheritance

Answer 12

Subclass can only add new methods and cannot override (keyword: final) = much better

Question 13

Generalization

Answer 13

subclass discovered first (biology; leads to model transformation)

Question 14

Characteristics of Behavioral Patterns and Examples

Answer 14

Choice between Algorithms & Model Complex Control Flows: Observer/Strategy

Question 15

Strategy Pattern

Answer 15

Add algo w/o disturbing the application/other algo’s: Policy decides stragegy.

Question 16

SA/SD

Answer 16

Structured Analysis/Structured Design: Preliminary Design + Detailed Design

Question 17

Contraction

Answer 17

Method Overriding with empty bodies (violates Liskov’s Substitution Principle = bad)

Question 18

Method Overriding

Answer 18

Implementation in subclass overrides function in superclass (same signature)

Question 19

Frameworks

Answer 19

partial application that can be specialized to produce custom applications (reusability & extensibility)

Question 20

Observer Pattern

Answer 20

models 1-to-Many Dependency between objects: ‘publish & subscribe’

Question 21

Object Model Optimization

Answer 21

improve performance (response time & memory utilization & …)

Question 22

Delegation

Answer 22

Catching operation and sending it to another object where it is already implemented. Reuse functionality of existing class. PRO: flexible & replaceable BUT: Encapsulation (inefficient)

Question 23

Component-Based Software Engineering fills design gap with …

Answer 23

available components (‘build’)

Question 24

Specification Inheritance

Answer 24

Subclassing from specification. Reuse of specified functionality of the superclass.

Question 25

Legacy System

Answer 25

system that has evolved over decades and is considered irreplaceable

Question 26

White Box Reuse

Answer 26

Inheritance/Subclassing: New Class reuses functionality of superclass + new functionality (use: specify interface + describe taxonomies)

Question 27

Reuse

Answer 27

Identification of existing solutions (inheritance & off-the-shelf & design patterns)

Question 28

Characteristics of Creational Patterns and Examples

Answer 28

Make System independent from the way its objects are created: Prototype/Singleton