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System Development Life Cycle

Dr. R. Murugesan

Associate Professor of Computer Science

C.P.A. College

Bodinayakanur.

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What is SDLC

A Framework that describes the activities performed at each stage of a software development project

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Phase-I�Preliminary Investigation

Tasks

  • What is the problem
  • Determine if a new system is needed
  • Whether an alternative system will solve the problem

Results

  • Need for improving the existing system is recognised

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Phase-II�Feasibility Study

  • Evaluate alternatives based upon
  • Economic Feasibility-Do benefits justify costs-Net Present Value
  • Technical Feasibility-Is reliable technology and training available
  • Operational Feasibility-Will the management and users support it
  • Value anlaysis

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Phase-3�System Analysis

  • Detailed study of various operations performed by the system
  • Studying the existing organisational history, structure, and culture
  • Define boundaries of the candidate system
  • Data collection or data gathering

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Phase-3�System Analysis

Tools

  • Data flow diagrams
  • Interviews
  • Onsite observations
  • Questionnaires
  • Data dictionaries

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Phase-3�System Analysis

  • Results
  • SRS (Software Requirement Specification) document is finalised which includes:
  • Functional and non-functional requirements
  • What the system will do and what it is not expected to do
  • Information about other systems with which system must interface

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Phase-4�System Design

  • Most creative and challenging phase
  • Translates the performance requirements into design specifications

Tasks

  • How should the problem be solved
  • Organisational and job designs prepared
  • Information processing systems design
  • Design of the database
  • Design of the user interface
  • Physical design
  • Input data and master files are designed
  • Output formats are designed

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Phase-4�System Design

Results

  • Detailed System Document
  • Procedural flowcharts
  • Record layouts
  • Report layouts
  • Workable plan for implementing candidate system

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Phase-5 �System Coding and Testing

  • Build the system to the design specifications
  • Develop the software
  • Acquire the hardware
  • Test the system for acceptance
  • Program Testing (Unit testing)
  • System Testing
  • User Acceptance Testing
  • Quality Assurance Testing

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Phase-6�System Implementation

  • Convert from old system to new system
  • Compile final documentation
  • Evaluate the new system

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Phase-6�System Implementation

  • Types of 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
  • Pilot approach-launched new system for only one group within the business
  • Phased/incremental approach-individual parts of new system are gradually phased-in over time

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Phase-7�System Maintenance

  • Types of Maintenance
  • Correction of new bugs found (corrective)
  • System adjustments to environmental changes and users’ changing needs (adaptive)
  • Enhancing the performance, changes to use better techniques when they become available (perfective)

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Thank you