Software Development Lifecycle (SDLC)

SDLC 6 Phase

1. Requirements Specification
   • Market research
   • Product definition
2. System Design
   • Specification of system(architecture, data structure, etc.)
   • Rigorous plan
3. Implementation
4. Testing
5. Deployment
6. Maintenance

Software Process Model

• Abstract representation of development process
• What, when, how to do in each phase

Waterfall Model

• Rigid sequential process of SDLC

Pros

• Easy to follow / estimate cost
• Strong control / documentation
• Scalable to large projects

Cons

• Requires perfect planning
• No flexible response to change

Waterfall Extension: Iterative Model

• Each iteration includes whole SDLC
• Feedback at the end of iteration

Waterfall Extension: V-Model

• Multiple testing to each level
• Acceptance/System/Integration/Unit Test

Waterfall Extension: Spiral Model

• Prototyping + Waterfall
• 4 phase
  • Determine objects / Requirements plan
  • Identify and resolve risk -> working prototype
  • Dev & Test
  • Plan for next iteration
• Higher cost
• Non-trivial scope

Agile Process

Goals

• Adaptive planning
• Evolutionary development & delivery
• Time-boxed iteration
• Rapid & flexible respnose to change

Agile Manifesto

• Individuals & Interaction over Processes & Tools
• Working Software over Comprehensive Documentation
• Customer Collaboration over Contract Negotiation
• Responding to Change over Following a Plan

Agile Manifesto 12 Principles

1. Early and continuous delivery
2. Welcome changing requirements
3. Deliver working software frequently
4. Work together daily
5. Motivated individuals
6. Face to face conversation
7. Working software is the primary measure of progress
8. Constant pace
9. Continuous attention to technical excellence and good design
10. Simplicity
11. Self-organizing teams
12. Reflects on how to become more effective, tunes the behavior at regular intervals

Waterfall vs. Agile

	Waterfall	Agile
Timeline	Fixed	Fixed (short term)
Client Involvement	No	Promoted
Budget	Fixed	Flexible
Success Rate(Easy/Difficult)	High / Low (architect-centric)	High / High (member-centric)
Documentations	Good	Poor

Rational Unified Process (RUP)

• Unified Process → All steps of SDLC unified in each phase
• Integration & Automation is the key
• Inception: What to build
  • Prepare vision documents and initial business case
    • Including risk assessment and resource estimate
  • Develop high-level project requirements
  • Manage project scope
    • Reduce risk by identifying all key requirements
• Elaboration: How to build
  • Detail requirements as necessary (~80%)
  • Produce an executable and stable architecture (~10% code implemented)
  • Drive architecture with key use cases
  • Verify architectural quality (reliability & scalability)
  • Continuously assess business case, risk profile and development plan
• Construction: Build
  • Build daily / weekly + automated build & test
  • Deliver fully functional software
• Transition: Verify & Deploy to Users

RUP Best Practice

• Adapt the process
• Balance stakeholder priorities
• Collaborate across teams
• Demonstrate value iteratively
• Elevate the level of abstraction
• Focus continuously on quality

Extreme Programming (XP)

• A set of principles that provides the highest value in the fastest way possible
• Most useful when plan is completely unclear

XP 5 Values

• Communication
• Simplicity
• Feedback
• Courage
• Respect

XP 12 Practices

• Fine Scale Feedback
  • Pair Programming (PP)
  • Planning Game
  • Test Driven Development (TDD)
  • Whole Team
• Continuous Process
  • Continuous Integration (CI)
  • Design Improvement
  • Small Release
• Shared Understanding
  • Coding Standards
  • Collective Code Ownership
  • Simple Design
  • System Metaphor
• Programming Welfare
  • Sustainable Pace

XP Roles

• Customer
• Developer
• Coach
• Tracker

Pair Programming (PP)

• Code Review to Extreme Level → Real-Time Review
• Driver (Code) & Navigator (Review)

Scrum

• Lightweight framework that helps generate value through adaptive solutions
• Sprint: unit cycle of iteration
• Sprint goal consists of working product

3 Scrum Goals

• Transparency
• Inspection
• Adaptation

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