Software Development Life Cycle (SDLC) is the application of standard business practices to building software applications. It’s typically divided into six to eight steps: Planning, Requirements, Design, Build, Document, Test, Deploy, Maintain.

Six Phases of the System Development Life Cycle

• Preliminary Investigation
  • Assesses feasibility and practicality of system
• System Analysis
  • Study old system and identify new requirements
  • Defines system from user’s view
• System Design
  • Design new/alternative system
  • Defines system from technical view
• System Development
  • New hardware and software is acquired, developed, and tested
• System Implementation
  • System installation and training
• System Operation & Maintenance
  • Daily operation
  • Periodic evaluation and updating

Preliminary Investigation – Software Development Life Cycle

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

System Analysis

• In depth study of the existing system to determine what the new system should do.
  • Expand on data gathered in Phase 1
• In addition to observation and interviews, examine:
  • Formal lines of authority (org chart)
  • Standard operating procedures
  • How information flows
  • Reasons for any inefficiencies

System Analysis Documentation Produced

Complete description of current system and its problems

• Requirements for new system including:
  – Subject
  – Scope
  – Objectives
  – Benefits
• Possible development schedule

System Design

1. Uses specifications from the systems analysis to design alternative systems
2. Computer – Aided Software Engineering (CASE) tools are software based products designed to help automate the production of information systems.

Examples:
– Diagramming Tools
– Data Repositories
– Prototyping Tools
– Test Data Generators
– Documentation Tools
– Project Management Tools

System Design Documentation Produced

• System Design Report
  – Describe Alternatives including:
  • Inputs/Outputs
  • Processing
  • Storage and Backup
• Recommend Top Alternative based upon:
  • System Fit into the Organization
  • Flexibility for the future
  • Costs vs. benefits

System Development

• Build the system to the design specifications
• Develop the software
• Purchase off the shelf software OR
• Write custom software
• Acquire the hardware
• Test the new system
• Module (unit) test – tests each part of system
• Integration testing – tests system as one unit
• Create manuals for users and operators

System Implementation

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

Operations & Maintenance

• Types of changes:
  – Physical repair of the system
  – Correction of new bugs found (corrective)
  – System adjustments to environmental changes
  – Adjustments for users’ changing needs (adaptive)
  – Changes to user better techniques when they become available (perfective)
• Evaluation Methods
  – Systems audit – performance compared to original specifications
  – Periodic evaluation – “checkups” from time to time, modifications if necessary

Advantages of Software Development Life Cycle SDLC

Increase
• Development speed
• Product Quality
Improve
• Tracking & Control
• Client relation
Decrease
• Project risk & Project management overhead