System Development Life Cycle

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Abdul HameedRoll No. 1059Semester 1st

B.S (HONS) I.T (Morning))

Submitted to: Sir Inam

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Objectives

Have been introduced to the Systems Development Life Cycle.

Learned about the stages (or steps) involved in system analysis.

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Structured Analysis

Structured analysis is the traditional way of moving from old outdated, or inefficient systems to new and improved ones.

This tradition uses a concept called the Systems Development Life Cycle.

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Systems request

Planning a new system usually begins with a formal request called a ‘system request’

The request describes problems, or desired changes in an information system or business process

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Systems Planning phase

The systems request usually initiates the Systems Planning phase of the System Development Life Cycle.

It can come from a top manager, a planning team, a department head, or even the IT Department of an Organisation.

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Systems Planning

Systems planning is the first stage in the System Development Life Cycle

In this first stage a preliminary investigation will take place to identify the nature and scope of the problem (or business opportunity)

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The entire Systems Development Life Cycle.(SDLC)

Describes activities and functions that all systems developers perform, and consists of the following steps (or stages):

1. System Planning (including Feasibility)2. System Analysis3. System Design4. Systems Implementation5. Systems Operation, support and security

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SDLC Models The systems Development Life cycle can be

described or modelled in different ways.

The most usual and well known model is called the ‘Traditional Life Cycle or (Waterfall) model’

The following is an illustration of what is meant by the ‘Waterfall model’

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INFO1409 Systems Analysis SDLC L05.ppt

© Copyright De Montfort University 2000All Rights Reserved

Traditional Life Cycle

SystemsInvestigation

SystemsAnalysis

SystemsDesign

SystemsImplementation

Support &Maintenance

FeasibilityStudy

ProjectSelection

“Waterfall” Approach

May have iterations butthese are very costly

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Activity time

Instructions:Work with the student sitting next to you.If you do not have one, then try to get involved

with a student or students either behind you, or in front of you.

Take ONE stage each of the SDLCDiscuss and record what you think the

activities in that stage would be.

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Stage 1 –Systems Planning

After the systems request the preliminary investigation begins

A key part of this investigation is a Feasibility Study

The Feasibility study reviews the anticipated costs and benefits to the Organisation and recommends a course of action.

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Stage 2 – Analysis

The results of the preliminary investigation and feasibility study lead to the second stage of the SDLC.

The purpose of the Systems Analysis phase is to build a logical model of the new system

The first step is requirements modelling.

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Analysis continued..

Requirements modelling

In requirements modelling, the analyst investigates the business processes to document what the new system must do.

Requirements modelling continues the investigation that began in systems planning.

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Stage 3 - Systems Design

.At this stage you design the User Interface1. Identify all necessary inputs, outputs

and processes.2. Design internal and external controls3. Show programmers how to transform

the logical design into program modules and code. (application architecture)

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Design (continued)

The result of the Design stage is documented in the

System Design Specification

This is presented to Managers and users for review and approval.

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Stage 4 -System Implementation

…involves the following activities: Programs are written, tested and

documented. The system is installed. Final preparations are made to convert

data to the new system’s files, and to train users).

A system evaluation is conducted

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Stage 5 –Systems Operation, Support and security

During this stage, the IT staff maintain, enhance and protect the system.

Maintenance corrects errors, and adapts to changes in the environment such as new tax rates.

Enhancement gives new features and benefits.

Security controls safeguard the system

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Well Designed Systems

“A well designed system will be secure, reliable, maintainable and scalable. A scalable development can expand to meet new business requirements and volumes. Information systems development is always a work in progress”

Page 22 chapter 1 Shelley et al Systems Analysis & Design 6 th Ed.

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Alternative SDLC model

This alternative model focuses on the interaction of planning,

analysis and design tasks which leads to implementation followed by operation and support.