CS 3050 Object-Oriented Analysis and Design

Objectives What is “Object-Oriented?” Object-Oriented Approach Vs. Structured Approach How Has the Object-Oriented Approach Evolved? What are the Benefits of the Object- Oriented Approach?

What is “Object-Oriented?” A computer system is viewed as a collection of objects. These objects have certain features, or attributes. They can also exhibit certain behaviors Similar things can be grouped and classified

What is “Object-Oriented?” Things or objects also interact such as People or other objects can interact with one another In building an information system, identify the objects that are needed We need only to know what the objects do and use them. Called this the building block approach

Object-Oriented Paradigm Capitalize on Object Oriented Programming (OOP) Models Real World Development Time Reduced Code Reuse Easier Class is a Representation of a System Data Behavior Encapsulation provides Modularity

Other Design Methodologies Functional Decomposition Data Decomposition Relational DB Artificial Intelligence/Expert Systems

Procedural vs. OOP Algorithmic Main Building Block: Procedure Functional Decomposition Difficult to Maintain Object-Oriented Main Building Block: Class Object is an instance of a Class Objects has identity, state, and behavior

Procedural vs. OOP

Object-Oriented Approach Vs. Structured Approach Structured Traditional approach: (See Fig 1.2) Computer systems is viewed as a collection of computer programs Procedural approach is usually complex. Three logic structures characterize structured programming : - sequence of set of instructions - choice on set of instructions - repetition of a set of instructions.

Structured methods and rules for more complex problems Structured systems analysis - hierarchy of procedures using - process model : Data Flow Diagrams - Data model: ER Diagrams Structured systems design – organizing smaller programs (Modular) & using a structure chart as a guideline for modular programming -hierarchy of smaller programs Object-Oriented Approach Vs. Structured Approach

Data Flow Diagrams

Entity-Relationship Modeling

Object Oriented Approach: New methods, rules and concepts are defined ( See Fig 1.1 ) Object-Oriented Analysis : - Defines all of the types of objects that are part of the user’s work environment Object-Oriented Design: -Defines additional types of objects, the user interface and operating environment and ways in which they interact Object-Oriented Approach Vs. Structured Approach

Object Oriented Programming: -programs written that define all objects to include their attributes and behaviors Structured & Object Oriented approaches are different in many ways BUT are also similar - the concept of identifying business events & defining users’ requirements - data modeling concepts & techniques - GUI & Internet Websites Object-Oriented Approach Vs. Structured Approach

How has the Object-Oriented Approach Evolved? SIMULA was first OO programming language in mid- sixties Smalltalk developed by Xerox in the seventies was instrumental in popularizing GUI interface C++ & Pascal with OO features arose in the eighties Object Oriented COBOL in the nineties More recently - pure object Oriented Java, J++ and VB Current OO methods use UML (Unified Modeling Language) to define constructs and models.

What are the Benefits of OO OO approach addresses THREE pervasive problems with traditional systems development Quality Productivity Flexibility Small, small-contained manageable objects reduces the complexity of the system development Reuse can greatly increase productivity Adding and changing objects can be done without interfering with the rest of the system