SDLC 2: Prototyping, Hybrid, and Custom Models

1. Prototype Model

The Prototype Model is used when project requirements are unclear or expected to evolve. It focuses on creating an initial version (prototype) that allows stakeholders to visualize the product early on and provide feedback.

Characteristics:

• Early Feedback: Builds a working model that users can interact with, allowing for adjustments based on feedback.
• Iterative Development: Prototypes are modified until they meet user expectations.

Use Cases:

• UI/UX-Focused Applications: Apps with heavy user interaction, where early design feedback is critical (e.g., mobile apps, e-commerce).
• Projects with Undefined Requirements: When requirements are vague or exploratory, prototypes help clarify expectations.

Advantages and Disadvantages:

• Advantages: Early identification of design flaws, increased user satisfaction, and flexible modifications.
• Disadvantages: Time-consuming if feedback isn’t managed, and can lead to scope creep if unchecked.

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2. Hybrid Model

The Hybrid Model combines multiple SDLC models to create a customized workflow, blending flexibility with structured processes. Often, Agile’s adaptability is paired with Waterfall’s structured phases for areas requiring strict control.

Characteristics:

• Customization: Adaptable to project needs by combining elements from different models.
• Best of Both Worlds: Allows fast iteration in some phases while maintaining rigidity where needed.

Use Cases:

• E-commerce Platforms: Frequent front-end updates (Agile) and a stable, secure backend (Waterfall) work well with hybrid models.
• Projects with Mixed Requirements: Projects needing agile frontend updates and stable backend development benefit from a hybrid approach.

Example: Hybrid CI/CD Pipeline Configuration

The following configuration runs continuous integration (CI) for agile changes while using a “security check” phase, typical in Waterfall, before production deployment.

# Hybrid CI/CD Pipeline Configuration
stages:
  - build
  - test
  - security_check
  - deploy

jobs:
  build_job:
    stage: build
    script:
      - echo "Building project..."
      - mvn clean package

  test_job:
    stage: test
    script:
      - echo "Running tests..."
      - mvn test

  security_check:
    stage: security_check
    script:
      - echo "Running security scans..."
      - ./run_security_check.sh
    rules:
      - if: $CI_COMMIT_BRANCH == "main"

  deploy_job:
    stage: deploy
    script:
      - echo "Deploying to production..."
      - ./deploy.sh

Advantages and Disadvantages:

• Advantages: Offers flexibility in front-end or iterative development while keeping back-end requirements secure and stable.
• Disadvantages: Requires effective management to handle different workflows and potential mismatches between agile and structured components.

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3. Derived Models

Derived models are tailored SDLC models customized to meet specific project or organizational needs by adapting an existing model to include additional steps or adjust workflows.

Characteristics:

• Custom Fit: Adjusts an existing model (e.g., Waterfall or Agile) based on specific project or organizational requirements.
• Highly Specific: Useful for projects with specialized needs, such as regulatory compliance or unique project constraints.

Use Cases:

• Healthcare Applications: Modifies Waterfall to add compliance testing for regulatory requirements.
• Projects with Specific Standards: Applications needing extra validation and verification steps for industry standards.

Example: Derived Waterfall Model with Custom Testing

A derived Waterfall model might include an extra verification phase after each step to ensure compliance and catch issues early.

Derived Waterfall Model – Phase Breakdown:

1. Requirement Collection:
   • Gather requirements, establish quality criteria, and set acceptance conditions.
2. Design:
   • Conduct high-level and low-level design reviews.
3. Custom Verification Stage:
   • Include a verification stage after design to ensure requirements alignment before coding.
4. Coding and Testing:
   • Developers build, and QA runs validation tests.
5. Deployment and Validation:
   • Final deployment includes end-user feedback and validation.

Advantages and Disadvantages:

• Advantages: Ensures compliance and aligns closely with organizational standards.
• Disadvantages: Can be complex to manage, especially when blending different workflows or adding extra stages.

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Summary

The Prototype, Hybrid, and Derived models provide adaptable solutions for projects with unique needs. These models are particularly valuable for projects that require:

• Early feedback (Prototype Model)
• Customizable workflows (Hybrid Model)
• Project-specific adjustments (Derived Model)

Next, we’ll dive into quality assurance within the SDLC, covering the Software Testing Life Cycle (STLC) and the Defect Life Cycle.