03 - Agile Methodology: Iterative and Incremental Development

Agile Methodology: Iterative and Incremental Development

The Agile methodology represents a revolution in software development. Born as a reaction to the limitations of traditional methods, Agile promotes flexibility, collaboration, and continuous value delivery to the customer.

The Birth of Agile: The Manifesto

In February 2001, 17 developers met at a ski resort in Snowbird, Utah. Their goal: find an alternative to the heavy, bureaucratic processes that dominated the software industry. From this meeting, the Agile Manifesto was born.

1️⃣ Individuals and interactions > Processes and tools
   └─ People are the heart of the project

2️⃣ Working software > Comprehensive documentation
   └─ Working code is the true measure of progress

3️⃣ Customer collaboration > Contract negotiation
   └─ Active partnership instead of rigid contracts

4️⃣ Responding to change > Following a plan
   └─ Adaptability is more important than rigid planning

Value 1: Individuals and Interactions

Agile recognizes that software is built by people, not processes. Face-to-face communication is more effective than complex documents and tools.

Value 2: Working Software

Working software is the primary metric of progress. Better working code with minimal documentation than perfect documents without code.

✅ DEFINITION OF DONE (DoD)
A user story is "Done" when:

□ Code written and peer reviewed
□ Unit tests written (coverage ≥ 80%)
□ Integration tests passed
□ API documentation updated
□ No critical bugs open
□ Product Owner approval
□ Deployed to staging environment
□ Acceptance criteria satisfied

Value 3: Customer Collaboration

The customer is not an "enemy" to protect yourself from with rigid contracts, but a collaborative partner who works together with the team.

Value 4: Responding to Change

Requirements change. Market changes. Technology changes. Agile embraces change instead of resisting it.

The 12 Agile Principles

Beyond the 4 values, the Manifesto includes 12 principles that guide Agile team behavior:

🎯 CUSTOMER SATISFACTION
1. Continuous delivery of value to customer
   └─ Frequent and incremental releases

2. Welcome changing requirements
   └─ Even late in development

⏱️ TIME-TO-MARKET
3. Deliver working software frequently
   └─ From weeks to months (preferably weeks)

🤝 COLLABORATION
4. Business people and developers work together
   └─ Daily collaboration

5. Build projects around motivated individuals
   └─ Give support and trust to the team

6. Face-to-face conversation
   └─ Most effective way to communicate

💯 QUALITY
7. Working software is the measure of progress
   └─ Not documents or completion percentages

8. Sustainable development
   └─ Maintain constant pace indefinitely

9. Continuous attention to technical excellence
   └─ Quality design improves agility

🔄 CONTINUOUS IMPROVEMENT
10. Simplicity: maximize work not done
    └─ Do only what's necessary (YAGNI)

11. Self-organizing teams
    └─ Best solutions emerge from the team

12. Regular retrospectives
    └─ Reflect and adapt behavior

Principles 1-3: Customer Focus

Principles 4-6: Collaboration

Principles 7-9: Quality and Sustainability

Principles 10-12: Simplicity and Improvement

Iterative and Incremental Cycle

The heart of Agile is iterative (repeated in cycles) and incremental (each cycle adds value) development.

📅 SPRINT (2 weeks example)

🔵 DAY 1: SPRINT PLANNING (4 hours)
├─ Part 1: WHAT (2 hours)
│  ├─ Product Owner presents backlog priorities
│  ├─ Team selects user stories for sprint
│  └─ Sprint Goal defined
└─ Part 2: HOW (2 hours)
   ├─ Team breaks down stories into tasks
   ├─ Estimate effort in hours
   └─ Sprint Backlog created

🟢 DAYS 2-9: DEVELOPMENT
├─ Daily Standup every morning (15 min)
│  ├─ What did I do yesterday?
│  ├─ What will I do today?
│  └─ Do I have impediments/blockers?
├─ Coding, testing, continuous integration
├─ Backlog Refinement (mid-sprint, 1 hour)
└─ Collaboration with Product Owner

🟡 DAY 10: SPRINT REVIEW (2 hours)
├─ Demo of completed work
├─ Stakeholders provide feedback
├─ Product Owner accepts/rejects stories
└─ Backlog updated with insights

🔴 DAY 10: SPRINT RETROSPECTIVE (1.5 hours)
├─ What went well?
├─ What went wrong?
├─ Action items to improve
└─ Team commitment

🔵 Repeat cycle with new Sprint...

User Stories and Backlog Management

✅ WELL-WRITTEN STORY
As an e-commerce customer,
I want to save products in a wishlist
so that I can purchase them in the future without searching again.

Acceptance Criteria:
- "Add to Wishlist" button on every product
- "My Wishlist" page accessible from header
- Ability to remove items from wishlist
- Wishlist persists between sessions (login required)

Story Points: 5
Priority: Medium

---

✅ TECHNICAL STORY (SPIKE)
As a development team,
I want to explore NoSQL databases (MongoDB vs DynamoDB)
so that we can choose the best solution for our use case.

Acceptance Criteria:
- Proof of concept with both
- Comparison document (performance, cost, scalability)
- Final recommendation

Timebox: 3 days
Priority: High (blocker)

Agile Metrics

1. Velocity

Definition: Story points completed per sprint (average).

Sprint | Committed | Completed | Velocity
-------|-----------|-----------|----------
   1   |    20     |    15     |   15
   2   |    18     |    18     |   16.5
   3   |    20     |    17     |   16.7
   4   |    17     |    19     |   17.3
   5   |    18     |    18     |   17.4 ← Stabilized

📊 Insights:
- Team has velocity ~17-18 story points
- Use for future planning
- Don't compare velocity between different teams!

2. Burndown Chart

Graph showing remaining work vs time.

Story Points
   ↑
40 │●
   │ ╲
30 │  ●╲        ← Ideal (dashed line)
   │   ╲●
20 │    ╲ ●
   │     ╲  ●   ← Actual (solid line)
10 │      ╲   ●
   │       ╲    ●
 0 └────────╲─────●─→ Days
   1  2  3  4  5  6  7  8  9 10

✅ GOOD: Actual follows ideal
⚠️ WARNING: Actual above ideal = at risk
❌ BAD: Flat actual = no progress

3. Cumulative Flow Diagram (CFD)

Visualizes work flow through states (To Do, In Progress, Done).

Agile Mindset and Culture

Agile is not just a process, it's a mindset. Deep cultural change.

Challenges in Agile Adoption

Agile vs Waterfall: When to Use What

Popular Agile Frameworks

Agile is an umbrella that includes various frameworks. The most used:

Conclusions

Agile has revolutionized the software industry by bringing focus on people, collaboration, and adaptability. It's not a magic formula but a mindset that requires cultural commitment and constant practice.