Software Development Life Cycle (SDLC)

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

Uses specifications from the systems analysis to design alternative systems
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