Agile Model & Its Frameworks¶

What is Agile?¶

The Agile Model is an iterative and incremental software development approach that emphasizes:

• Customer collaboration over contract negotiation
• Working software over documentation
• Responding to change over following a strict plan
• Continuous delivery & improvement

Unlike the Waterfall model, which follows a strict sequence, Agile is flexible, adaptive, and fast-paced.

User Stories¶

User stories are a key component of agile software development. They are short, simple descriptions of a feature or functionality from the perspective of a user.

Pattern of User Story¶

User stories are completely from the end-user perspective which follows the Role-Feature-Benefit pattern.

• As a [ type of user ], I want [ an action ], so that [ some reason ]

Writing User Stories¶

User stories are from a user perspective. So when user stories are written, users are given more importance during the process. Some points outlined which are taken into consideration during writing user stories like

• Requirements
• Tasks and their subtasks
• Actual user
• Importance to user words/feedback
• Breaking user stories for larger requirements

INVEST Principles of User Stories¶

A good user story should be based on INVEST principle which expresses the quality of the user story.

• Independent – Not dependent on other.
• Negotiable – Includes the important avoid contract.
• Valuable – Provide value to customer.
• Estimable – It should be estimated.
• Small – It should be simple and small not complex.
• Testable – It should be evaluated by pre-written acceptance criteria.

C’s in User Stories¶

• Card – Write stories on cards, prioritize, estimate and schedule it accordingly.
• Conversation – Conduct conversations, Specify the requirements and bring clarity.
• Confirmation – Meet the acceptance criteria of the software.

Phases of Agile Development¶

Agile follows an iterative approach, meaning the software is developed in small increments (sprints or iterations).

1. Concept & Initiation¶

• Define project vision and high-level goals.
• Identify key stakeholders and set expectations.

2. Planning¶

• Break down requirements into user stories and prioritize them.
• Plan sprints (typically 1-4 weeks).

3. Design & Development¶

• Develop small working features in each sprint.
• Continuous integration and testing are done simultaneously.

4. Testing & Review¶

• Frequent testing ensures quality.
• Stakeholders review and provide feedback after each sprint.

5. Release & Deployment¶

• Each sprint delivers a working software increment to the users.
• Deployment is done continuously (CI/CD pipeline).

6. Maintenance & Continuous Improvement¶

• Gather feedback and improve the next sprint.
• Monitor performance and apply patches.

Agile Lifecycle¶

flowchart TD
A[Plan] --> B[Design]
B --> C[Develop]
C --> D[Test]
D --> E[Release]
E --> F[Feedback]
F -->|Next Sprint| A

Agile Frameworks & Methodologies¶

Agile isn’t a single process but has multiple frameworks that implement Agile principles differently. Here are the most popular ones:

1. Scrum (Most Popular)¶

🔹 Best for: Teams working on complex projects with evolving requirements.

🔹 Key Features:

• Work is divided into Sprints (1-4 weeks).
• The team follows Daily Stand-up Meetings (15 min).
• Defined roles: Scrum Master, Product Owner, Development Team.
• Sprint Review & Retrospective after each sprint.

-- Scrum Master – Removes obstacles, ensures Agile principles.

-- Product Owner – Defines features, prioritizes backlog.

-- Development Team – Delivers the work in Sprints.

🔹 Example Use Cases:

• Mobile app development (WhatsApp, Instagram).
• Game development (incremental feature releases).

Scrum Flowchart¶

flowchart LR
    A[Product Backlog] --> B[Sprint Planning]
    B --> C[Sprint Backlog]
    C --> D[Daily Scrum]
    D --> E[Sprint Review]
    E --> F[Sprint Retrospective]
    F -->|Next Sprint| B

2. Kanban (Visual Workflow Management)¶

🔹 Best for: Continuous delivery projects that require real-time tracking.

🔹 Key Features:

• Uses a Kanban Board to track work progress.
• Work items move from To Do → In Progress → Done.
• Focus on reducing bottlenecks and improving workflow efficiency.
• No fixed iterations like Scrum; work is continuously delivered.

🔹 Example Use Cases:

• Customer support systems (Zendesk, ServiceNow).
• Content publishing workflows (Blogs, YouTube video releases).

Kanban Flowchart¶

flowchart LR
    A[To Do] --> B[In Progress]
    B --> C[Testing]
    C --> D[Done]

3. Extreme Programming (XP) (Code-Focused)¶

🔹 Best for: High-risk projects that require fast-paced coding & testing.

🔹 Key Features:

• Test-Driven Development (TDD) – Write tests before coding.
• Pair Programming – Two developers work on the same code together.
• Continuous Integration (CI) – Code is frequently merged and tested.
• Customer involvement in every sprint.

🔹 Example Use Cases:

• FinTech applications (real-time transactions, fraud detection).
• AI and machine learning projects (frequent model tuning).

XP Flowchart¶

flowchart TD
    A[User Stories] --> B[Planning]
    B --> C[Pair Programming]
    C --> D[Unit Testing]
    D --> E[Continuous Integration]
    E --> F[Small Release]
    F -->|Next Iteration| A

    style C fill:#f9f,stroke:#333
    style D fill:#f9f,stroke:#333

4. Lean Software Development (Speed & Efficiency)¶

🔹 Best for: Companies that focus on eliminating waste and maximizing value.

🔹 Key Features:

• Minimize unnecessary work (avoid extra documentation).
• Automate repetitive tasks.
• Deliver software as quickly as possible.
• Encourage team empowerment & decision-making.

🔹 Example Use Cases:

• E-commerce platforms (Amazon, Flipkart).
• Startups building MVPs (Minimum Viable Products).

Comparison of Agile Frameworks¶

Advantages¶

• Faster development cycles → Early & continuous delivery.
• Customer-focused → Frequent feedback improves quality.
• Better risk management → Issues identified early.
• Higher team collaboration → Teams work closely with stakeholders.

Disadvantages¶

• Not suitable for all projects → Works poorly in highly regulated environments (e.g., medical devices).
• Requires experienced teams → Needs self-discipline & adaptability.
• Less predictability → No fixed deadlines like Waterfall.

Note: Good for business systems, challenging for safety-critical systems.