Skip to content

Object Oriented Analysis

The intent of object oriented analysis is to define all classes, their relationships and their behaviors.

The tasks involved are: 1. Static Model 1. Identify classes (attributes and methods are defined) 2. Specify class hierarchy 3. Identify object-to-object relationships 4. Model the object behavior 2. Dynamic Model 1. Scenario diagrams

Object Oriented Design

OOD transforms the analysis model into design model which serves as a blueprint for our software.
There are 4 layers of OOD pyramid: 1. The subsystem layer: Representation of each of the subsystems which enable our software to fulfil customer requirements and act as a blueprint for technical infrastructure for those requirements. 2. The class and object layer: This layer contains the class hierarchies including generalizations and specializations along with the design representation of each object. 3. The message layer: This layer specified the internal and external interfaces the objects will have in order to communicate with each other. 4. The responsibility layer: This layer contains the data-structures and algorithms to handle the attributes and methods of the objects.

Abbot’s Textual Analysis

This technique of identifying objects is one of the oldest.
Parts of speech are identified and then are modeled.
Pasted image 20240525183110.png

Example

Problem Statement

A simple cash register has a display, an electronic wire with a plug, and a numeric keypad, which has keys for subtotal, tax, and total. This cash storage device has a total key, which triggers the release on the drawer. The numeric buttons simply place a number on the display screen, the subtotal displays the current total, the tax key computes the tax, and the total key adds the subtotal to the tax.

Tasks

  1. Identify all the classes in this problem statement.
  2. Eliminate the unnecessary classes.

Nouns(initial)

  • Register
  • Display
  • Wire
  • Plug
  • Keypad
  • Keys
  • Devices
  • Release
  • Drawer
  • Buttons
  • Screen
  • Number
  • Total
  • Tax

Nouns(general knowledge)

  • 0-9 keys
  • Money
  • Tax Key
  • Total Key
  • Subtotal Key

Eliminating Irrelevant / Redundant Nouns

  • Register
  • Display
    • Wire, Irrelevant
    • Plug, Irrelevant
  • Keypad
  • Keys
    • Devices, vague
    • Release, Irrelevant
  • Drawer
    • Buttons, redundant
    • Screens, redundant
    • Number, attribute
    • Total, attribute
    • Total, attribute
  • 0-9 Key
    • Value, attribute
  • Money
  • Subtotal Key
  • Tax Key
  • Total Key