Software Process Models

Software Process Models – A software process model is a structured framework that defines the sequence of activities involved in software development, from requirement analysis to maintenance.

Why Process Models are Needed

• Provide disciplined development approach
• Improve project planning and control
• Reduce risk and cost
• Ensure quality and timely delivery

Major Activities in Any Process Model ⭐

1. Requirement Analysis
2. System Design
3. Implementation (Coding)
4. Testing
5. Deployment
6. Maintenance

GFG Software Developments Life Cycle Models (SLDC)

Types of Software Process Models ⭐

1. Waterfall Model ⭐

Requirement
     ↓
Design
     ↓
Implementation
     ↓
Testing
     ↓
Deployment
     ↓
Maintenance

• linear and sequential model
• Each phase must be completed before next starts
• Phases : Requirement → Design → Implementation → Testing → Deployment → Maintenance
• Advantages
  • Simple and easy to manage
  • Clear documentation
• Disadvantages
  • No flexibility
  • Late testing
  • Not suitable for changing requirements

2. Iterative Waterfall Model ⭐

Requirement ↰
     ↓      |
  Design    |
     ↓      |
Implementation
     ↓
 Testing
     ↓
 Deployment

• Enhanced waterfall with feedback paths
• Allows returning to previous phase
• Advantages :
  • Error correction possible
  • Better than classical waterfall
• Disadvantages :
  • Still rigid
  • Late delivery of working software

3. Incremental Model

Req → Design → Code → Test → Release (Inc 1)
Req → Design → Code → Test → Release (Inc 2)
Req → Design → Code → Test → Release (Inc 3)

• Software developed in small increments
• Each increment adds functionality
• Advantages
  • Early delivery
  • Reduced risk
  • Customer feedback possible
• Disadvantages
  • Requires good planning
  • Integration issues

4. Spiral Model

                 Planning
                    ↑
      Evaluation ←           → Risk Analysis
                    ↓
                Engineering
                    ↑
            (Next Spiral Loop)

• Risk-driven model
• Combines waterfall and prototyping
• Each Loop: Planning → Risk Analysis → Engineering → Evaluation
• Advantages
  • Strong risk management
  • Suitable for large systems
• Disadvantages
  • Complex
  • High cost

5. V-Model

Requirement        Acceptance Testing
     ↓                     ↑
System Design     System Testing
     ↓                     ↑
Architecture      Integration Testing
     ↓                     ↑
Module Design     Unit Testing
     ↓
Coding

• Verification and Validation focused
• Each development phase has corresponding test phase
• Advantages
  • Early test planning
  • High reliability
• Disadvantages
  • Inflexible
  • No early prototype

6. Prototyping Model

Requirement
     ↓
Quick Design
     ↓
Prototype
     ↓
User Evaluation
     ↓
Refined Requirement
     ↓
Final System

• Prototype built to understand requirements
• Types
  • Throwaway Prototype
  • Evolutionary Prototype
• Advantages
  • Clarifies requirements
  • User involvement
• Disadvantages
  • Poor documentation risk
  • Prototype mistaken as final product

7. Agile Model

Plan → Design → Develop → Test → Deploy
  ↑                                ↓
  ←────────── Feedback ────────────

• Iterative and incremental
• Focus on customer collaboration
• Principles
  • Working software over documentation
  • Responding to change
• Advantages
  • High adaptability
  • Continuous feedback
• Disadvantages
  • Less documentation
  • Needs experienced team

8. RAD (Rapid Application Development)

Requirements Planning
        ↓
User Design ↔ Prototyping
        ↓
Construction
        ↓
Cutover (Deployment)

• Fast development using reusable components
• Advantages
  • Short development time
  • High productivity
• Disadvantages
  • Not suitable for large systems
  • Requires skilled developers

9. Big Bang Model

Requirements + Design + Code + Test
               ↓
            Product

• No planning
• All resources applied at once
• Advantages
  • Simple
  • Suitable for small projects
• Disadvantages
  • High risk
  • Not scalable

Comparison (Exam)

• Waterfall: rigid, document-heavy
• Iterative Waterfall: feedback paths
• Spiral: risk-driven
• Agile: change-driven
• V-Model: testing-centric

One-Line Exam Definitions

• Waterfall: Linear sequential model
• Spiral: Risk-based iterative model
• Agile: Flexible, customer-driven model
• Incremental: Functionality delivered in parts