Program Development Life Cycle (PDLC)
Program Development Life Cycle (PDLC)
The Program Development Life Cycle (PDLC) provides a structured approach to creating software. Different life‑cycle models suit different project contexts, risk levels, and stakeholder requirements. Below are the most common models, each described in terms of its core principles, benefits and drawbacks.
1. Waterfall Model
The Waterfall model follows a linear, sequential flow where each stage must be completed before the next begins.
Principles
Benefits
Drawbacks
Strict phase order: Requirements → Design → Implementation → Testing → Maintenance.
Documentation is produced at the end of each phase.
Changes are discouraged once a phase is completed.
Clear milestones and deliverables.
Easier project tracking and budgeting.
Well‑suited to projects with stable, well‑understood requirements.
Inflexible to requirement changes.
Late discovery of design or implementation errors.
Often results in a product that does not fully meet user needs.
2. Incremental Model
The system is built and delivered in small, functional increments, each adding new features.
Principles
Benefits
Drawbacks
Divide the overall system into independent modules.
Each increment passes through a mini‑waterfall cycle.
Feedback from earlier increments informs later ones.
Early delivery of usable functionality.
Reduced risk – problems are identified early.
Flexibility to reprioritise features.
Requires good overall architecture planning.
Integration testing can become complex.
Potential for inconsistent user interface across increments.
3. Prototyping Model
A prototype (an early, simplified version of the system) is built to explore requirements and design ideas.
Principles
Benefits
Drawbacks
Rapid construction of a working model.
Iterative refinement based on stakeholder feedback.
Prototype may evolve into the final system or be discarded.
Improves understanding of user requirements.
Reduces risk of costly rework later.
Facilitates early user involvement.
Stakeholders may mistake prototype for final product.
Potential for inadequate documentation.
Can lead to scope creep if changes are continuously added.
4. Spiral Model
The Spiral model combines iterative development with systematic risk analysis at each loop.
Principles
Benefits
Drawbacks
Each spiral loop includes: planning, risk analysis, engineering, and evaluation.
Risk assessment drives the order of activities.
Allows multiple iterations and refinements.
Explicit focus on risk mitigation.
Adaptable to large, complex, high‑risk projects.
Stakeholder feedback incorporated regularly.
Complex to manage and document.
Higher cost and longer development time.
Requires expertise in risk assessment.
5. Agile (Scrum) Model
Agile emphasises flexibility, collaboration, and rapid delivery through short, time‑boxed iterations called sprints.
Principles
Benefits
Drawbacks
Iterative development in 2‑4 week sprints.
Cross‑functional, self‑organising teams.
Continuous stakeholder involvement and backlog refinement.
High responsiveness to changing requirements.
Frequent delivery of working software.
Improved team morale and communication.
Less emphasis on upfront documentation.
Requires disciplined team and stakeholder commitment.
Scope can become uncontrolled without strong product ownership.
6. V‑Model (Verification & Validation)
The V‑Model extends the Waterfall by pairing each development phase with a corresponding testing phase, forming a “V” shape.
Principles
Benefits
Drawbacks
Development phases on the left side (requirements → design → coding).
Testing phases on the right side (unit, integration, system, acceptance).
Each test level directly validates its corresponding design level.
Clear traceability between requirements and tests.
Early planning of test activities.
Suitable for safety‑critical systems.
Still rigid like Waterfall; changes are costly.
Heavy documentation overhead.
Limited flexibility for evolving requirements.
Suggested diagram: Comparative overview of the six PDLC models showing flow, iteration points, and risk handling.