itm 362 lecture - 2

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Systems Analysis and Design Lecture Slides

by: Maxwell Dorgbefu Jnr. 1

ITM 362; SYSTEMS ANALYSISAND DESIGN

LECTURE TWO

1. THE SYSTEMDEVELOPMENT LIFE CYCLE

(SDLC).


by: Maxwell Dorgbefu Jnr.

Key Ideas

An opportunity to create business value fromusing information technology initiates a project.

Feasibility analysis helps determine whether ornot to proceed with the IS project.

Projects are selected based on business needsand project risks.



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Key Ideas

The project sponsor is a key person whoidentifies business value to be gained fromusing information technology.

The approval committee reviews systemrequests from groups throughout theorganization and selects projects for the benefitof the business.



System Development Life Cycle(SDLC)

The Systems Development Life Cycle (SDLC) is ageneral term used to describe the method andprocess of developing a new information system.

Without the structure and organization providedby SDLC approach, projects are at risk for misseddeadline, low quality etc.

SDLC provides Structure

Methods Controls

Checklist

Needed for successful information system development.



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Why SDLC ?

We need SDLC in Information Systems

development to:

Facilitate project review

Improve communication

Provide a more efficient/effective system

Guide the system development

Improve management and control

Ensure systems are within budget and meetuser/clients taste.



SDLC Phases - 1Sets of related activities are organized into phases:

1. Preliminary investigation

2. System Analysis

3. System Design

4. System Development

5. System Implementation and6. System Support and Maintenance



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SDLC Phases - 1

1.

Preliminary

Investigation

4. System

Development

Starting Point

Systems Analysis and Design

Lecture Slides by: Maxwell

Dorgbefu Jnr.

The Preliminary Investigation Determine if a new system is needed

Three primary tasks:

Define the problem

By observation and interview, determine what

information is needed by whom, when, where

and why

Suggest alternative solutions

Prepare a short report



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Analysis Phase

Primary objective: to understand and document the

information needs and processing requirements of

the new system.

Gather information (e.g. interview, read, observe etc.)

Define system requirements (reports, diagrams etc.)

Build prototypes for discovery of requirements

Prioritize requirements

Generate and evaluate alternative solutions Review recommendations with management



Analysis Phase Understand the existing system

Gather data

Analyze data

Establish system requirements



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Analysis- Data Gathering

Written documents

InterviewsStructuredUnstructured

Questionnaires

ObservationVisits by appointmentParticipant observation

Sampling



Analysis-Analyze Data How the current system works

Determine system requirements

Basis for documentation

Tools

Data flow diagram (DFD)

Decision tables



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Analysis System Requirements

Detailed list of things the system must be able

to do

Design is based upon system requirements

Agreement upon requirements is needed

before proceeding



Analysis Report to Management

Summarize problems

Describe requirements

Cost analysis

Recommendations for next step

Obtain authorization to proceed



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Design Phase

Objective: to design the solution (not to

implement it though)

The two sub phases of the design phase are:

Preliminary design

Detail design



Design Phase Preliminary Design

Major system aspects

Centralized or distributed

Online or batch

PC-based?

How will input be captured?

Necessary reports



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Make or buy decision

Packaged softwareMeet at least 75% of requirements?Change business procedures for part or all of

remainder?Customize for part of all of remainder?

Custom softwareProgrammers write code

OutsourcingSystem is developed by external organization




Build a prototype

Limited working system of subset

Does not need true functionality

Output looks like anticipated system output

Working model that can be modified and fine-tuned

Uses high-level software tools CASE Best for small-scale systems



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Presentation

All alternatives

Selected plan

Prototype of the system




Design Phase Detail Design

Parts of detail design phase

Output requirements

Input requirements

Files and databases

Systems processing

Systems controls and backup



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Output requirements

Medium

Type of reports

Contents

Input requirements

Medium

Content

Input forms

Validation

Volume


Files and Databases

Organization

Access

Format of records

Coordinate with database administrator

regarding external databases and updating




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Systems Controls and Backup

Ensure that input is processed correctly

Prevent fraud and tampering

System journals

Backup of system files




Report to Management

Detailed design specifications report

Presentation




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Development Phase

Doing the work to bring the new system into

being

This phase involves

Scheduling

Coding/Programming and

Testing



Development Phase Programming

Refine the design

Converting detailed logic flowcharts and

pseudocode into programs

Testing

Unit testing

System testing

Volume testing



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Implementation Phase

Information system is built, tested and installed

(actual programming of the information system)

Activities

Construct software components

Verify and test

Develop prototypes for tuning

Convert data

Train and document Install the system



Implementation - Conversion

Direct/plunge/crash approach entire new system

completely replaces entire old system, in one step

Parallel approach - both systems are operated side by

side until the new system proves itself

Pilotapproach - launched new system for only one

group within the business -- once new system is

operating smoothly, implementation goes company-wide

Phased/incremental approach - individual parts ofnew system are gradually phased-in over time, using

either crash or parallel for each piece.



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Support and Maintenance Phase

Objective is to keep the information system running afterits installation.

Maintain system

Small patches, repairs, and updates

Enhance system

Small upgrades or enhancements to expand systemcapabilities

Larger enhancements may require separatedevelopment project

Support users

Help desk and/or support team



End of Lecture !!!

See you next week.



Questions & Comments ???.....

itm 362 lecture - 2

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