introduction to business systems development

8/13/2019 Introduction to Business Systems Development

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Introduction to

Business SystemsDevelopment

BCO1048


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Topic 5

Satzinger 4th edn. Chapter 2,6,7


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Satzinger et al (2006) Fig 2-3

Review of the SDLC


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Objectives

Explain the differences between a model,a tool, a technique, and a methodology

Describe the two overall approaches usedto develop information systems: thetraditional method and the object-orientedmethod

Describe some of the variations of thesystem development life cycle (SDLC)


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Objectives

Describe some of the key features of

current trends in system development:

the spiral model, extreme programming(XP), and the Rational unified process

(RUP)

Explain how computer-aided systemengineering (CASE) tools are used in

system development


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Aids to Assist in Analysis and

Design Methodologies

Comprehensive guidelines to follow for completingevery SDLC activity

Collection of models, tools, and techniques

Models Representation of an important aspect of the real

world Diagrams and charts

Project planning aids


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Types of Models

Models may be classified in several ways

One method is to classify models into

Graphical Mathematical

Narrative

Physical


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System Development Models

Some models of Systems Components

Flowchart

Data Flow Diagram (DFD) Entity-Relationship Diagram (ERD)

Structure Chart

Use Case Diagram

Class Diagram

Sequence Diagram



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System Development Models

Some models used to manage SDLC

PERT Chart

Gantt Chart Organisational Hierarchy Chart

Financial Analysis Models

NPVNet Present Value ROIReturn on Investment



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Design

Tools

Software support that helps create modelsor other project components

From simple drawing programs to complexCASE tools


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Some Tools Used in System

Development Project management application Drawing graphics application

Word processor/text editor

Computer-aided system engineering (CASE)tools

Integrated development environment (IDE)

Data management application

Reverse-engineering tool Code generator tool



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Design

Techniques

Collection of guidelines that help theanalyst complete a system development

activity or task

Step-by-step instructions General advice


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Some Techniques Used

in System Development Strategic planning techniques

Project management techniques

User interviewing techniques Data-modelling techniques

Relational database design techniques

Structured analysis & design technique Object-oriented analysis & design techniques

Software testing techniquesSatzinger et al (2006) Fig 2-10


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Relationships Among

Components of a Methodology

Techniques Models

Tools


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Two Approaches to

System Development1. Traditional Approach

Structured system development

Structured programming Structured analysis

Structured design

Structured programming

Known as Structured Analysis andDesign Technique (SADT)

2. Object-Oriented Approach


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Phases can

be variedSatzinger et al (2006) Fig 2-4

Waterfall Model of SDLC


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Top-Down Programming

Divides complex programs into hierarchy ofmodules

Module at top controls execution by callinglower level modules

Modular programming Similar to top-down programming

One program calls others to work as single system


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Top-Down or Modular

Programming


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Structured Design

Developed to provide guidelines

What the set of programs should be

What each program should accomplish How programs should be organized into a

hierarchyStructure Chart

Main principles of program modules Loosely coupled

Highly cohesive


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Satzinger et al (2006) Fig 2-14Structure Chart


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Structured Analysis

Helps developer define what the system

needs to do (processing requirements)

Data to store and use Inputs and outputs

How functions work together

DFDs and ERDs commonly show

results of structured analysis


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Data Flow Diagram ~ VIP!


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ERD ~ VIP! (Data Model created

during Structured Analysis)


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Structured Analysis Leads to Structured

Design and Structured Programming


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Information Engineering

A System development methodology

that focuses on strategic planning, data

modeling, and automated tools More rigorous and complete than the

structured approach

Uses process dependency diagrams More focus on dataand CASE


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Object-Oriented Approach

Focus on

things of

interestand how

they

behave


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Object-Oriented Analysis &

Design Object-oriented analysis

Defines all of the types of objects that do the work

of the system

Shows how objects interact

Object-oriented design

Defines all additional object types needed to

communicate with people and devices in thesystem

Refines each type of object for implementation


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Object-Oriented Programming

Writing statements in programming

language to define each object

Benefits include naturalness and reuse


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SDLC Variations

Analysts encounter many variations of

SDLC in practice

Based on: Phases

Iteration

Emphasis on people Speed of development


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Extreme Programming (XP)

Recent development approach Lightweight approach to keep process simple

Starts with user stories

Developers document stories with informaldescriptive models

Acceptance tests define outcomes

Iterative in nature Heavy user involvement

Series of releases

Continuous testing and integration


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Rational Unified Process (RUP)

Object-oriented development approach

Reinforces six best practices

Develop iteratively Define and manage system requirements

Use component architectures

Create visual models

Verify quality

Control changes

Inception, elaboration, construction, and transition


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ADE Tools

Application development environments

(ADEs) are:

integrated software development tools

provide all the facilities necessary to develop new

application software

maximise speed and quality

A common synonym is integrated

development environment (IDE)


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Computer-Aided System

Engineering (CASE) Automated tools to improve the speedand quality of system development work

Support the drawing of models Provide for the translation of systemmodels into application programs

Database of information about systemcalled repository

Upper CASE, Lower CASE, ICASE


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CASE ToolRepository contains

all system Information


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Homework

Review this lecture From Satzinger et al.

Readand summarize

pages 35-68

Complete

Review questions

11,15,18,23 (page 69)

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