8 Software Development Life Cycle (SDLC) Methodologies

The Software Development Life Cycle (SDLC) is a structured process used by software developers to design, develop, and test high-quality software. SDLC methodologies are the roadmaps that guide this process. Understanding various SDLC methodologies is crucial for selecting the right approach that aligns with project goals and requirements. This guide explores the leading SDLC methodologies to help you make informed decisions for your software development projects.

What is An SDLC Methodology?

SDLC methodology is a systematic process followed during software development to ensure high-quality and efficient production. It encompasses a series of phases including planning, analysis, design, implementation, testing, deployment, and maintenance. Each phase serves a distinct purpose and contributes to the successful completion of a software project. 

SDLC methodologies provide a structured approach to software development, helping teams to manage project scope, timelines, and resources effectively. Common methodologies include Waterfall, V-Model, Agile, Lean, Iterative, Spiral, Incremental, and DevOps, each with unique characteristics and applications.

8 Popular SDLC Methodologies

Waterfall Model

The Waterfall Model is the most traditional Software Development Life Cycle (SDLC) methodology. It follows a linear, sequential approach, where each phase of the development process is completed one after another before moving on to the next. This model is likened to a waterfall, cascading through various stages without turning back. 

The typical phases include:

• Phase 1: Planning and Requirements Analysis.
• Phase 2: System Design and Architecture.
• Phase 3: Development and Coding.
• Phase 4: Verification and Testing.
• Phase 5: Deployment.
• Phase 6: Maintenance.

The Waterfall Model is ideal for projects with well-defined requirements and limited need for flexibility. However, its rigidity makes it less suitable for complex projects with evolving requirements. Here are some ideal scenarios for Waterfall method:

• Developing a simple internal business application with a clear set of functionalities.
• Building a basic e-commerce website with a standard set of features.
• Creating a point-of-sale system for a retail store with established business rules.

V-Model

The V-Model, also known as the Verification and Validation model, is an extension of the Waterfall model. It emphasizes the parallel relationship between development stages and their corresponding testing phases, forming a V-shaped lifecycle. Each development phase has a directly associated testing phase, ensuring that verification and validation are integrated throughout the development process.

The V-Model enhances the traditional Waterfall approach by integrating verification and validation at each development stage. This makes it suitable for projects where quality and reliability are paramount. However, its rigidity and resource demands makes it less suitable for more dynamic projects or those requiring a faster development pace. Here are some practical use cases for V-model:

• Developing safety-critical systems like medical devices or aviation software.
• Building embedded systems with strict performance requirements.
• Creating financial applications where data integrity and security are paramount.

Iterative Model

>>  Read more: In-depth Explanation Of Iterative and Incremental Development

The Iterative Model is a software development approach that builds a system incrementally through repeated cycles (iterations). Unlike the Waterfall model, where each phase must be completed before the next begins, the Iterative Model revisits phases, allowing for refinement and improvements based on feedback and evolving requirements.

The core principle is to break down the project into smaller, manageable iterations. Each iteration typically involves activities like planning, requirements definition, design, development, testing, and deployment. User feedback is then gathered and incorporated into the following iteration.

The Iterative Model is ideal for projects with evolving requirements and a need for user involvement. However, proper planning and scope control are crucial to avoid getting bogged down in endless iterations. Here are some popular use cases for Iterative model:

• Developing a new social networking platform with constantly evolving features.
• Building a content management system (CMS) with a growing list of functionalities.
• Creating a complex e-commerce website with dynamic product features.

Incremental Model

The Incremental Model is a software development approach that divides the system into smaller, manageable increments or parts, which are developed and delivered in successive cycles. This model allows for partial deployment of the system and early delivery of some functional components, providing users with usable software early in the development process.

This model shares some similarities with the Iterative Model. However, the difference lies in their delivery focus: while the Iterative Model focuses on continuous improvement of the whole product, the Incremental Model focuses on progressively adding functionality until the entire system is complete.

Each increment typically follows a mini-waterfall lifecycle within itself, involving requirements gathering, design, development, testing, and deployment. Let’s consider the incremental development process of a Healthcare Management System:

• Initial Planning and Analysis:
  • Define overall system requirements.
  • Plan the increments and prioritize features.
• Incremental Development and Delivery:
  • Increment 1:
    • Planning: Identify essential features such as patient registration and appointment scheduling.
    • Development: Develop the patient registration module.
    • Testing: Conduct unit testing on the patient registration module.
    • Delivery: Deploy the system with basic functionality.
    • Evaluation: Collect feedback from healthcare providers.
  • Increment 2:
    • Planning: Plan for adding electronic health records (EHR) management.
    • Development: Implement EHR management functionality.
    • Testing: Perform integration testing with the patient registration module.
    • Delivery: Release the updated system with EHR management.
    • Evaluation: Gather feedback on EHR usability.
  • Increment 3:
    • Planning: Add features for billing and insurance processing.
    • Development: Develop billing and insurance modules.
    • Testing: Test the new modules and ensure compatibility with existing features.
    • Delivery: Deploy the system with full billing and insurance processing capabilities.
    • Evaluation: Review system performance and user feedback.

>> Read more about Healthcare software:

• Key Benefits of Healthcare Automation Systems
• Top 8 Healthcare Apps For Patients & Clinics
• Data Security in Healthcare Software: Why Is It Important?
• Tips for Enhancing Healthcare UI Design in Mobile Apps

The Incremental Model is well-suited for projects with clearly defined functionalities and phased deployment needs. For example:

• Developing a point-of-sale (POS) system with modules for sales, inventory management, and customer relationship management (CRM).
• Building a learning management system (LMS) with features for course creation, student enrollment, and progress tracking, delivered in phases.
• Creating a complex enterprise resource planning (ERP) system with modules for finance, human resources, and supply chain management, rolled out incrementally.

Spiral Model

The Spiral Model is a risk-driven software development process model that combines elements of both iterative and incremental models. It emphasizes continuous risk assessment and iterative refinement through a series of spirals, or cycles, each encompassing four main phases:

• Planning: Define objectives, identify constraints, and determine alternatives.
• Risk Analysis: Identify and evaluate risks, develop strategies to mitigate them, and prototype possible solutions.
• Engineering: Develop and verify the next level of the product, implementing identified solutions.
• Evaluation: Assess the progress, plan the next iteration, and gather stakeholder feedback.

In short, the Spiral Model emphasizes building prototypes and gathering feedback throughout the development process. Let's consider the example of a Large-Scale Enterprise System developed based on the Spiral Model, to see how this approach unfolds in practice.

• Iteration 1:

  • Planning: Identify basic requirements, such as user management and data storage.
  • Risk Analysis: Assess risks related to data security and scalability.
  • Engineering: Develop a prototype for the user management module.
  • Evaluation: Test the prototype, gather user feedback, and plan the next iteration.

• Iteration 2:

  • Planning: Focus on transaction processing capabilities.
  • Risk Analysis: Identify and mitigate risks associated with transaction integrity and performance.
  • Engineering: Develop and integrate  the transaction processing module.
  • Evaluation: Evaluate system performance, gather feedback, and plan further enhancements.

The Spiral Model is well-suited for large and complex projects with high-risk factors and need for early user feedback. For instance:

• Developing a new online banking system with complex security and regulatory requirements.
• Building a large enterprise software application with constantly evolving functionalities.
• Creating a medical device with critical safety considerations, where early risk identification is paramount.

Agile Model

The Agile Model is a flexible and iterative approach to software development that emphasizes collaboration, customer feedback, and rapid delivery of functional software. It is characterized by its ability to adapt to changing requirements and deliver small, incremental improvements through continuous iterations.

Let’s visualize how Agile method works via a practical example below:

Development of a Mobile Banking App

• Sprint 1:

  • Planning: Define and prioritize features such as account balance viewing and transaction history.
  • Development: Implement and test account balance feature.
  • Review: Demonstrate the feature to stakeholders, gather feedback.
  • Retrospective: Discuss what went well and what can be improved.

• Sprint 2:

  • Planning: Focus on transaction history feature.
  • Development: Implement and integrate transaction history functionality.
  • Review: Present the updated app to stakeholders, collect feedback.
  • Retrospective: Identify improvements for the next sprint.

The Agile Model is well-suited for projects with evolving requirements, need for rapid feedback, and uncertain technologies. Examples:

• Developing a mobile app with constantly evolving features based on user feedback.
• Building a web application where user needs and market demands are constantly changing.
• Creating a complex software product with a high degree of uncertainty about the final requirements.

Lean Model

The Lean Model is a software development approach derived from lean manufacturing principles. It focuses on delivering maximum value to the customer by minimizing waste and optimizing processes. 

The core principles of the Lean Model include:

• Value: Identify what truly constitutes value for the customer and the organization. Focus on delivering that value efficiently.
• Eliminate Waste: Identify and remove activities that do not add value, including factors like time, materials, resources, and effort.
• Build Quality In: Integrate quality assurance into the development process, preventing defects from the outset, rather than fixing them later.
• Create Knowledge: Promote continuous learning and knowledge sharing.
• Defer Commitment: Delay irreversible decisions until the last responsible moment.
• Deliver Fast: Deliver small, incremental releases quickly.
• Respect People: Empower team members and encourage collaboration.
• Optimize the Whole: Focus on the entire value stream, not just individual parts.

Several tools and techniques support the implementation of Lean principles:

• Value Stream Mapping: Visually map the entire process flow to identify potential areas of waste and inefficiency.
• Kanban Boards: Visualize workflow stages and limit work in progress (WIP) to improve efficiency.
• 5S Methodology: A workplace organization system that emphasizes Sort, Set in Order, Shine, Standardize, and Sustain.
• Kaizen Events: Dedicated brainstorming sessions focused on identifying and eliminating waste within a specific process.

DevOps Model

The DevOps Model is a software development methodology that integrates development (Dev) and operations (Ops) teams to improve collaboration, efficiency, and the continuous delivery of high-quality software. It emphasizes automation, continuous integration and continuous delivery (CI/CD), and the use of shared tools and processes to streamline the development lifecycle.

>> Read more about DevOps:

• CI/CD vs DevOps: Key Differences & How They Work Together?
• Top 9 Best DevOps Deployment Tools for Businesses
• DataOps vs DevOps: Similarities, Differences & Use Cases
• Top 22 Best DevOps Automation Tools For Businesses
• 7 Ways DevOps Speeds Up the Digital Transformation

Look through a practical example of a web application development process based on DevOps:

• Collaboration: Development and operations teams work together to plan, build, and deploy the application.
• Automation: Implement CI/CD pipelines using tools like Jenkins, GitLab CI, or CircleCI to automate testing and deployment.
• Continuous Integration: Developers regularly commit code to a shared repository, triggering automated builds and tests.
• Continuous Delivery: Each successful build is automatically prepared for deployment, ensuring that the application can be released at any time.
• Monitoring: Use tools like Prometheus and Grafana for continuous monitoring and alerting to track application performance and health.

Below is the Comparison Table of Key Factors for 8 SDLC Methodologies:

>> Read more: Product Metrics in Software Engineering: Types, Techniques, Tools

Final Thoughts

The world of software development offers a wide range of methodologies, each with its strengths and considerations. The choice of SDLC model significantly impacts the success of a software project.

Waterfall and V-Model suit well-defined projects, while Iterative and Incremental models handle evolving requirements. Spiral excels in risk management, Agile and Lean promote flexibility and efficiency, and DevOps emphasizes continuous integration and deployment. Understanding these models helps in selecting the best approach for achieving high-quality software that meets user needs efficiently.