Structured process for building and maintaining software from idea to retirement.

Structured processes ensure software is delivered reliably, on-time, and aligned with user needs.

#Phases

SLDC has many phases

1. Planning
2. Requirements Analysis
3. Design
4. Development
5. Testing
6. Deployment
7. Operations & Maintenance

There are also extended phases

• Proof of Concept (PoC)
• Continuous Improvement

#Planning

aka Feasibility Study, Concept Phase, Project Initiation

• Define objectives, scope, stakeholders, and high-level requirements
• Assess feasibility (technical, financial, operational, etc.)

#Requirements Analysis

aka Business Analysis, Discovery, Requirement Engineering

• Collect functional & non-functional requirements
  • functional: what the product does and how it behaves
  • non-functional: more broad metrics (e.g. uptime, etc.)
• Document requirements in Software Requirements Specification (SRS)

#Design

aka System Design, Architecture & Modeling, Technical Design

• Translate requirements into system architecture
• High-level design (HLD): architecture, modules, data flow
• Low-level design (LLD): detailed algorithms, database schemas

#Development

aka Implementation, Coding, Programming

• Actual programming of the software
• Translate design and requirements into working code
• Integrating modules, building features

#Testing

aka Verification, Validation, Quality Assurance (QA)

• Ensure the software meets requirements.
• Types of testing
  • Unit Testing
  • Integration Testing
  • System Testing
  • User Acceptance Testing
  • Regression Testing

#Deployment

aka Release, Delivery

• Delivering the product to the user environment
• Involves setting up servers, databases, and configurations

#Operations & Maintenance

aka Maintenance, Operations, Support

• Bug fixing, patching, performance tuning
• Performance monitoring
• Feature upgrades
• Adapting to new requirements

#Proof of Concept

aka Prototyping

• Building a mock-up or prototype before full development
• Common in Agile, Spiral, and Design Thinking

#Continuous Improvement

• Agile/Devops treat this as an ongoing cycle
• Integrates monitoring and user feedback after deployment

#Models

#Waterfall

Royce, 1970

• Linear, sequential process
• Clear documentation
• Rigid structure, inflexible to change
• Weakness: design issues found later intesting

  

  

#V-Model

Late 80s, early 90s

• Matches dev phases with test phases
• Focus on quality and testing early in the process.
• Weakness: still rigid, better for slow-changing requirements

  

#Spiral

Boehm, 1088

• Iterative cycles combining development + risk analysis
• Good for large, complex, or high-risk projects
• Weakness: can be costly and require strong risk management

  

#Agile

#Manifesto

• Individuals and interactions over processes and tools
• Working software over comprehensive documentation
• Customer collaboration over contract negotiation
• Responding to change over following a plan

#Methodologies

• Iterative, incremental delivery in short cycles.
• Focus on customer collaboration, adaptability, and continuous feedback
• Integrated with Devops: automation, CI/CD, and continuous improvement.

#Roles and Responsibilities

#Business Analyst / Product Owner

• Defines requirements & priorities

#Software Architect / Designer

• Creates system architecture & design

#Developer / Programmer

• Builds features & integrates components

#Tester / QA Engineer

• Verifies quality through testing

#Agile Coach

• Facilitates team process & removes blockers

#Devops Engineer

• Automates builds, testing, deployment, and monitoring

#UI/UX Designer

• Ensures usability and customer experience

#Site Reliability Engineer (SRE)

• Focuses on reliability, scalability, and performance.