34524234 Introduction to System Analysis and Design

8/8/2019 34524234 Introduction to System Analysis and Design

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INTRODUCTION TO SYSTEM

ANALYSIS AND DESIGN


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Introduction

Systems are created to solve problems

An organized way of dealing with a problem System Analysis and Design (SAD) mainly dealswith the software development activities


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DEFINING A SYSTEM

A collection of components that work together torealize some objective forms a system

There are three major connected andinterdependent components in every system Input Processing

Output The objective of the system demands that some

output is produced as a result of processing thesuitable inputs


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SYSTEM LIFE CYCLE

System life cycle is an organizational process ofdeveloping and maintaining systems

The process helps in developing a system plan(overall list of processes and sub-processes)required for developing a system.

System development life cycle means

combination of various activities In the System Analysis and Design terminology,

the system development life cycle meanssoftware development life cycle


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Phases of software development cycle

System study

Feasibility study System analysis

System design

Coding

Testing Implementation

Maintenance


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System Study

System study is the first stage of system development life cycleaimed at understanding the physical system

In practice, the system study is done in two phases Phase-I involves preliminary survey of the system to identifying the

scope of the system. Phase-II is a more detailed and in-depth study in which the

identification of users requirement and the limitations andproblems of the present system are studied

This phase concludes with a system study proposal containing

findings of current system and recommendation for the newrequirements To summarize

problem identification and project initiation background analysis inference or findings


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Feasibility Study

It is a test of the proposed system in the light of

its workability, meeting users requirements,effective use of resources and the costeffectiveness

Main goal is not to solve problem but achieve the

scope. End results are a greater accurate estimation of

costs and benefits


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System Analysis

Analysis involved a detailed study of the current system,leading to specifications of a new system

Involves collection of the available files, decision pointsand transactions handled by the present system

Specification of what the new system is to accomplishbased on the user requirements

Functional hierarchy showing the functions to be

performed by the new system and their relationship witheach other

List of attributes of the entities - these are the data itemswhich need to be held about each entity (record)


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System Design

Design of the new system based on userrequirements and the detailed analysis

The design proceeds in two stages: Preliminary or general design Structure or detailed design

In the preliminary design, the features of the

new system are specified, costs and benefitsestimated

If found feasible, the detailed design stagebegins with the computer oriented work


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System Design (contd..)

several tools and techniques used for designing

as Flowchart

Data flow diagram (DFDs)

Data dictionary

Structured English Decision table

Decision tree


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Coding

After design, the entire system is converted into

a computer understandable language The computer programs coordinate the datamovements and control the entire process in asystem.


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Testing

Before actually implementing the new systeminto operations, a test run of the system is doneremoving all the bugs

Test plans are developed and test cases areexecuted with test data. The output of the testrun should match the expected results.

Using the test data following test run are carriedout: Unit test System test


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Implementation

Implementation is the stage of a project during

which theory is turned into practice Users are trained onto the new system

Following strategies are used forimplementation

Parallel run Pilot run

Big bang approach


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Maintenance

Maintenance is necessary to eliminate errors in

the system during its working life and to tunethe system to any variations in its workingenvironment

The review of the system is done for:

knowing the full capabilities of the system knowing the required changes or the additional

requirements

studying the performance

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34524234 Introduction to System Analysis and Design