Understanding Object-Oriented Systems: Concepts, Evolution, and Databases, Slides of Introduction to Database Management Systems

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Object Oriented Databases

In this chapter, you will learn:

• What basic concepts govern OO systems
• How OO features are related to the more traditional relational and ER models
• What the basic features of an OO database management system (OODBMS) are
• What effect OO concepts are likely to have on data modeling and design

Object Orientation and Its Benefits

• A set of design and development principles based on conceptually autonomous computer structures known as objects
• Each object represents a real-world entity with the ability to act upon itself and interact with other objects
• Modularity is therefore almost inevitable

Object Orientation

Contributions

The Evolution of Object Oriented

Concepts (continued)

• Object oriented programming languages were developed to: - Provide an easy-to-use software development environment - Provide a powerful software modeling tool for application development - Decrease development time by reducing the amount of code - Improve programmer productivity by making that code reusable

The Evolution of Object Oriented

Concepts (continued)

• Object oriented environment has several important attributes: - Data set is no longer passive - Data and procedures are bound together, creating an object - Object has an innate ability to act on itself

Objects: Components and

Characteristics

• Object:
  • Abstract representation of a real-world entity
  • Has:
    • Unique identity
    • Embedded properties
    • Ability to interact with other objects and act upon itself
  • Defining characteristic is its unique identity

Real-World Student

Objects

Attributes (Instance Variables)

• Attributes:
  • Known as instance variables in OO environment
• Domain:
  • Logically groups and describes the set of all possible values that an attribute can have

Object Attributes

Messages and Methods

• Method:
  • Code that performs a specific operation on object’s data
  • Protects data from direct and unauthorized access by other objects
  • Used to change the object’s attribute values or to return the value of selected object attributes
  • Represent real-world actions Docsity.com

Depiction of an Object

Objects Send Messages

to Each Other

Classes

• Collection of similar objects with shared structure (attributes) and behavior (methods)
• Class instance or object instance
  • Each object in a class