MELJUN CORTES Developing Information System

8/10/2019 MELJUN CORTES Developing Information System

1/16

1

Developing

Business Information Systems

MELJUN CORTES


2/16

Copyright Prentice Hall, Inc. 2

Objectives

Once you have read and studied this presentation, youshould be able to understand and learn the following: The four stages of the system life cycle.

The basic system development techniques and the conceptsassociated with these techniques.

The scope and capabilities of CASE (Computer-Aided SoftwareEngineering) tools.

The concepts and phases of prototyping, including the generalactivities that take place during system analysis and design.

Approaches to converting an existing information system to anew one.

Basic programming concepts and the programming process, aswell as an overview of popular programming languages.


3/16


The System Life Cycle

Stages of the Life

Cycle

Birth Development

Production

End-of-life


4/16


Applications Software

Buy it Proprietary software

package

Rent itApplications service

provider (ASP)

Make it Develop a custom

information system


5/16


System Development Techniques and Concepts

Structured System Design Structure chart encourages top-down design

Payroll

System

Employee

Database

Report

Process

General

Ledger

CreationMainte-

nanceHourly Salary


6/16


System Development Techniques

Entity Symbol Process Flow line

Data Storage

Data Flow Diagram: Focus is on information flow

Entity Relationship Diagram:Focus is on

attributes of entities and relationship between them.


7/16


System Development Techniques

Combination of symbols and flow lines portrays the

logic of the program or system

Flowcharting

Main Program Loop Subroutines

Online

Storage

Input/

Output DisplayPrinted

Output

Computer

ProcessPredefined

Process

No

Yes

Terminal

PointDecision


8/16


Computer-Aided Software Engineering

CASE tools

Design tools

Information repository tools

Program development tools

Software engineers

Custom programs


9/16


Design Tools

The CASE design tools User interface

Screen generator

Layout

Report generator

Information repository tools Cross-referencing system (database)

Packages system documentation

Program development tools Application generator

Generation of text data


10/16


Prototyping

Developing PrototypeSystems Scalable systems

System specifications (specs) Functional specifications

Three Objectives Analyze current situation

Identify information needs

Develop a model of the target

system

Rapid ApplicationDevelopment (RAD)


11/16


The Prototyping Process

Phase I Define System

Specifications

Phase II Create Prototype System

Phase III Develop Operational

System

Phrase IV Develop System

Specifications


12/16


System Conversion and

Implementation Systems and acceptance

testing Unit testing

Systems testing

Uses test data and thenlive data

Approaches to systemconversion Parallel conversion

Direct conversion Phased conversion

Pilot conversion


13/16


The System Becomes Operational

Emphasis switches

from development to

operations System Maintenance

Modifications

Patches


14/16


Programming

A program solves a problem Uses logic

Design program logic beforewriting it

Nothing more than a set ofinstructions

Programming Languages: Machine Language

Procedure-Oriented: COBOL

Object-Oriented (OOP):

Smalltalk and C++ Fourth Generation (4GL)

Visual Programming: VisualBASIC


15/16


Writing the Program

System specification

review

Program identificationand description

Coding, testing, and

documentation


16/16

Documents

MELJUN CORTES Developing Information System