Software Development Process Models Explained
Software Development Life Cycle (SDLC)
The Software Development Life Cycle is a framework that defines how software is developed step by step.
Core Software Engineering Activities
- Software Specification
- Software Development
- Software Validation
- Software Evolution
Typical Development Flow
Planning → Requirements Analysis → System Design → Implementation → Testing → Maintenance
Software Process Structure
A Software Process consists of: Phase → Activity → Task
Process Activities Require:
- Resources (people, time, tools, money)
- Responsibilities
- Pre-conditions and Post-conditions
Waterfall Model
Definition
A sequential development process where each phase must be completed before the next phase begins.
Advantages
- Simple and easy to understand
- Clear structure
- Easy project management
Disadvantages
- Difficult to change requirements
- Testing happens late
- High risk if requirements are wrong
When to Use
When requirements are stable and well defined.
Incremental Development Model
Definition
Software is developed and delivered in small functional parts.
Advantages
- Early delivery of working software
- Easy to handle requirement changes
- Easier customer feedback
Disadvantages
- Difficult to see full system progress
- System structure may become weaker
Key Idea
Deliver working software early and improve gradually.
Feasibility Study
Definition
Analysis to determine if the project is possible and worth doing.
Types of Feasibility
- Technical Feasibility: Is the necessary technology available?
- Economic Feasibility: Is it financially worthwhile?
- Operational Feasibility: Will users accept and use it?
- Schedule Feasibility: Can it be finished on time?
- Legal Feasibility: Does it follow laws and regulations?
Output
Decision to continue or stop the project.
Reuse-Oriented Software Engineering
Definition
Software is built by assembling existing software components.
Examples
- Web services
- Software component libraries
- Commercial Off The Shelf (COTS) software
Advantages
- Faster development
- Lower cost
- Higher reliability
Disadvantages
- Less control over the final system
- Compatibility issues
- Licensing or legal issues
Spiral Model
Definition
A risk-driven development model that combines iterative development and risk analysis.
Main Focus
- Risk identification
- Risk reduction
- Prototyping
- Customer feedback
When Used
Large or high-risk projects.
V Model (Verification and Validation Model)
Definition
Each development phase has a corresponding testing phase.
Example:
- Requirements → Acceptance Testing
- Design → System Testing
- Implementation → Unit Testing
Main Idea
Testing is planned from the beginning.
Iterative Development Model
Definition
Software is developed in repeated cycles where each version improves the previous one.
Business Case
Definition
A document that explains why a project should be developed.
Includes
- Business problem
- Expected benefits
- Cost estimation
- Risks
- Alternative solutions
Data Protection Compliance
Software engineering must follow data protection laws like the Moroccan CNDP and the European GDPR. The CNDP requires authorization before deploying software that processes personal data. GDPR enforces privacy by design and strict data protection rules with heavy penalties. These laws protect user privacy, increase software security, and prevent misuse of personal data.