UNIVERSITY OF WEST ATTICA
SCHOOL OF ENGINEERING
DEPARTMENT OF COMPUTER ENGINEERING AND INFORMATICS

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Software Quality and Reliability

Software Life Cycle Models and Methodologies

Vasileios Evangelos Athanasiou
Student ID: 19390005

GitHub · LinkedIn

Georgios Theocharis
Student ID: 19390283

GitHub

Omar Alhaz Omar
Student ID: 19390010

GitHub · LinkedIn

Supervisor: Christos Troussas, Assistant Professor

UNIWA Profile · LinkedIn

Co-Supervisor: Akrivi Krouska, Assistant Professor

UNIWA Profile · LinkedIn

Athens, February 2024

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Software Life Cycle Models and Methodologies

This document provides a theoretical overview of various Software Development Life Cycle (SDLC) models and methodologies, ranging from traditional sequential models to modern agile and collaborative approaches. It was prepared by students at the University of West Attica, Department of Informatics and Computer Engineering.

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Table of Contents

Section	Folder/File	Description
1	docs/	Documentation on software life cycle models and methodologies
1.1	docs/Software-Life-Cycle-Models-and-Methodologies.pdf	Documentation (English)
1.2	docs/Μοντέλα-και-Μεθοδολογίες-Κύκλου-Ζωής-Λογισμικού.pdf	Documentation (Greek)
2	models/	Software development models illustrations
2.1	models/EN/	Model diagrams (English)
2.1.1	models/EN/agile.png	Agile model diagram
2.1.2	models/EN/DevOps.png	DevOps model diagram
2.1.3	models/EN/Extreme-programming.png	Extreme Programming model diagram
2.1.4	models/EN/functional.png	Functional model diagram
2.1.5	models/EN/Prototype.png	Prototype model diagram
2.1.6	models/EN/scrum.png	Scrum model diagram
2.1.7	models/EN/Spiral.png	Spiral model diagram
2.1.8	models/EN/test-driven.png	Test-Driven Development diagram
2.1.9	models/EN/unified_process.png	Unified Process diagram
2.1.10	models/EN/V-Model.png	V-Model diagram
2.1.11	models/EN/waterfall.png	Waterfall model diagram
2.2	models/GR/	Model diagrams (Greek)
2.2.1	models/GR/agile.png	Agile model diagram (Greek)
2.2.2	models/GR/DevOps.jpg	DevOps model diagram (Greek)
2.2.3	models/GR/Extreme.png	Extreme Programming diagram (Greek)
2.2.4	models/GR/Functional.png	Functional model diagram (Greek)
2.2.5	models/GR/model V.jpg	V-Model diagram (Greek)
2.2.6	models/GR/Prototype.png	Prototype model diagram (Greek)
2.2.7	models/GR/Scrum.png	Scrum model diagram (Greek)
2.2.8	models/GR/Spiral-Model.png	Spiral model diagram (Greek)
2.2.9	models/GR/Test-driven.png	Test-Driven Development diagram (Greek)
2.2.10	models/GR/Unified-process.jpg	Unified Process diagram (Greek)
2.3	models/Intro3.jpg	Introductory slide/image
2.4	models/questions.jpg	Questions / summary slide
3	presentation/	Course presentation slides
3.1	presentation/#GR_Software-Methodologies_Present.pptx	Presentation slides (Greek version)
3.2	presentation/Μοντέλα-και-Μεθοδολογίες-Κύκλου-Ζωής-Λογισμικού.pptx	Presentation slides (Greek)
4	README.md	Repository overview and usage instructions

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General Introduction

The Software Life Cycle (SDLC) is a structured framework guiding a project from inception to completion, defining stages such as requirements analysis, design, development, delivery, and maintenance.

• SDLC Model: Defines the stages of a software project.
• Methodology: A set of practices, techniques, and procedures used to organize and control development activities within those stages.
• Goal: To provide structured guidelines that improve efficiency and help achieve project objectives.

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1. Basic Software Development Models

1.1 The Waterfall Model

The Waterfall model is a linear and sequential development approach where each phase must be completed before moving to the next.

Typical Phases

• Requirements Analysis
• Architectural Design
• Detailed Design
• Coding and Testing
• System Testing
• Maintenance

Advantages

• Simple and easy to understand
• Well-structured and easy to manage
• Suitable for projects with stable and clearly defined requirements

Disadvantages

• Very rigid and inflexible
• Errors are often discovered late in development
• Returning to previous phases is difficult and costly

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1.2 The V-Model

The V-Model extends the waterfall approach by associating each development phase with a corresponding testing phase.

Structure

Left Side (Development Phases)

• Requirements analysis
• System design
• Architectural design
• Detailed design

Right Side (Testing Phases)

• Unit testing
• Integration testing
• System testing
• Acceptance testing

Key Focus

• Verification and validation at each stage
• Frequently used in safety-critical or high-reliability systems

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1.3 Other Basic Models

The document also introduces additional development models:

• Prototyping Model: Early software versions are built to clarify requirements and improve communication with stakeholders.
• Functional Augmentation Model: Features are added incrementally over time.
• Spiral Model: Combines iterative development with risk analysis and systematic planning.

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2. Modern Software Development Methodologies

Modern methodologies focus on flexibility, collaboration, and rapid delivery.

Key approaches include:

• Unified Process (UP): Iterative and incremental development framework.
• Agile Development: Emphasizes flexibility, customer collaboration, and continuous improvement.
• DevOps: Integrates development and operations to enable continuous integration and delivery.
• Scrum & Extreme Programming (XP): Agile frameworks emphasizing teamwork, feedback, and iterative progress.
• Test-Driven Development (TDD): Tests are written before implementation to guide development.

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3. Choosing a Methodology

The final section of the report discusses how to select an appropriate development methodology based on:

• Project size and complexity
• Requirement stability
• Risk levels
• Team expertise
• Organizational environment

Selecting the correct methodology ensures better resource utilization, smoother development, and higher-quality results.

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Conclusion

Understanding both classical and modern SDLC models helps organizations choose suitable development approaches. Proper selection and application of methodologies significantly improve project success and software quality.