Software Process Engineering

What is a Software Process?

A software process is an ordered set of activities aimed at producing a software product.

Key components:

• Activities — what is done (requirements, design, coding, testing)
• Roles — who does it
• Artefacts — what is produced
• Tools — what supports the work

Classic Lifecycle Models

• Waterfall — sequential phases; each phase finishes before the next begins
• Incremental — core product first, then added in increments
• Spiral — risk-driven; each loop refines requirements and design
• Unified Process (UP) — iterative, use-case driven, architecture-centric

The V-Model

The V-Model maps development phases to corresponding test phases:

• Unit Tests ↔ Component Design
• Integration Tests ↔ System Architecture
• System Tests ↔ Requirements Specification
• Acceptance Tests ↔ Business Requirements

The Agile Manifesto (2001)

Individuals and interactions over processes and tools

Working software over comprehensive documentation

Customer collaboration over contract negotiation

Responding to change over following a plan

Scrum Framework

Scrum is the most widely used Agile framework.

Roles: Product Owner · Scrum Master · Development Team

Events: Sprint · Sprint Planning · Daily Scrum · Sprint Review · Retrospective

Artefacts: Product Backlog · Sprint Backlog · Increment

Introduction

Git is the de facto standard version control system. In this lab you will learn the core workflow used in professional teams:

• Commit — snapshot of your changes
• Branch — isolated line of development
• Merge / Rebase — integrate changes
• Pull Request — propose and review changes

Core Git workflow

# Initialise and make first commit
git init my-project
cd my-project
echo "# My Project" > README.md
git add README.md
git commit -m "Initial commit"

# Create and switch to a feature branch
git checkout -b feature/login-page

# After making changes...
git add .
git commit -m "Add login page HTML"

# Push branch and open a Pull Request
git push -u origin feature/login-page

Continuous Integration

CI automatically builds and tests your code on every push, catching integration problems early.

A GitHub Actions workflow is defined in YAML and lives in .github/workflows/.

Simple CI workflow (.github/workflows/ci.yml)

name: CI

on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main]

jobs:
  build-and-test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 22
          cache: npm
      - run: npm ci
      - run: npm test

What is Technical Debt?

Technical debt is the implied cost of future rework caused by choosing an easy solution now instead of a better approach.

Types of technical debt:

• Intentional — deliberate shortcuts to meet a deadline
• Unintentional — poor practices; lack of knowledge
• Bit rot — code that decays as its environment evolves

Code Quality Metrics

Key metrics for measuring code quality:

• Cyclomatic Complexity — number of independent paths through code
• Code Coverage — percentage of code exercised by tests
• Code Duplication — repeated logic (DRY principle)
• Coupling & Cohesion — how modules depend on each other