2.6.1 Waterfall Model

• Description: Sequential, linear approach where each phase must be completed before the next begins.
• Key Characteristics:
  • Sequential phases with limited overlap.
  • Heavy emphasis on planning, schedules, budgets, and documentation.
  • Formal sign-offs after each phase.
• Strengths:
  • Suitable for less experienced teams.
  • Easy to track progress.
  • Ensures quality, reliability, and maintainability.
• Weaknesses:
  • Inflexible and costly to make changes later.
  • Problems often detected late (during testing).
  • Poor handling of requirement changes.

2.6.2 Incremental Model

• Description: System is developed in small, functional increments.
• Key Characteristics:
  • Combines Waterfall with iterative prototyping.
  • Delivers system in mini-waterfalls (increments).
• Strengths:
  • Early delivery of working components.
  • Easier risk management and flexibility.
• Weaknesses:
  • System architecture issues may arise.
  • Rigid phase boundaries.
  • Interfaces must be well-defined.

2.6.3 Software Reengineering and Reverse Engineering

• Software Reengineering: Restructures and updates existing systems without changing functionality.
• Activities:
  • Inventory Analysis
  • Document Restructuring
  • Design Recovery
  • Code Restructuring
  • Data Restructuring
  • Forward Engineering
• Reverse Engineering: Analyzes software to understand functionality for rebuilding or improvement.

2.6.4 Object-Oriented Software Development (OOSD)

• Description: Organizes software around objects that represent real-world entities.
• Key Concepts:
  • Classes and Objects
  • Inheritance
  • Polymorphism
• Advantages:
  • Handles diverse data types.
  • Models complex relationships.
  • Scalable and flexible.
• Applications: Web applications, AI, CAM.

2.6.5 Component-Based Development

• Description: Uses pre-built software components to build applications.
• Types of Components:
  • In-Process Client Components
  • Stand-Alone Client Components
  • Stand-Alone Server Components
  • In-Process Server Components
• Strengths:
  • Reduces development time.
  • Encourages modularity and reusability.
• Weaknesses:
  • Requires continuous integration.
  • Poorly defined requirements can cause failure.

2.6.6 Web-Based Application Development

• Description: Uses web technologies for lightweight, scalable applications.
• Technologies:
  • SOAP (Simple Object Access Protocol)
  • WSDL (Web Services Description Language)
• Advantages:
  • Platform independence.
  • Real-time integration.
• Challenges:
  • Risk of redundant tasks.
  • Complexity in integration across APIs.

2.7 Selection of SDLC Model

• Factors for Selection:
  • Team size and skills.
  • Technology constraints.
  • Project size and complexity.
  • Stakeholder priorities.

2.8 Iterative Development Models

2.8.1 Prototyping Methodology

• Description: Builds a quick prototype for user feedback before full-scale development.
• Phases:
  • Identify Requirements
  • Develop Initial Prototype
  • Test and Revise
  • Obtain User Signoff
• Strengths:
  • Early detection of issues.
  • Improves user participation.
• Weaknesses:
  • Inadequate analysis.
  • Frequent requirement changes.

2.8.2 Spiral Model

• Description: Iterative model focusing on risk management.
• Key Characteristics:
  • Iterative prototyping and refinement.
  • Risk analysis at each phase.
• Strengths:
  • Risk-focused.
  • Flexible for large projects.
• Weaknesses:
  • Complex management.
  • Skilled project management required.

2.8.3 Rapid Application Development (RAD)

• Description: Focuses on quick development through iterative prototyping and user involvement.
• Strengths:
  • Fast delivery.
  • Encourages user feedback.
• Weaknesses:
  • Quality may be compromised.
  • Poor documentation.

2.8.4 Agile Software Development

• Description: Iterative approach with a focus on collaboration, flexibility, and customer feedback.
• Key Characteristics:
  • Time-boxed iterations.
  • Close team collaboration.
  • Continuous feedback loops.
• Strengths:
  • Quick response to changing requirements.
  • High-quality outcomes.
• Weaknesses:
  • Poor documentation.
  • Lack of long-term planning.

2.8.5 DevOps

• Description: Integrates development and operations teams for seamless delivery.
• Strengths:
  • Faster delivery cycles.
  • Improved collaboration.
• Risks: Potential security vulnerabilities.

2.8.6 DevSecOps

• Description: Integrates security practices throughout the SDLC.
• Key Controls:
  • Automated vulnerability scanning.
  • Security training for developers.