Software Development Life Cycle (SDLC)

What is the Software Development Life Cycle (SDLC)?

The software development life cycle (SDLC) is a systematic process for designing, developing, and testing software. It consists of a series of phases that guide the project from start to finish.

Key Takeaways

The SDLC is a systematic process for designing, developing, and testing software.
SDLC involves seven phases: planning, analysis, design, implementation, testing, deployment, and maintenance.
Integrating security at each SDLC phase helps protect applications from vulnerabilities and ensures compliance.
Different SDLC models, such as Waterfall, Agile, and Spiral, offer various approaches to software development.
The SDLC provides a structured framework that helps manage risks, control costs, and ensure software quality.

History of SDLC

The concept of the SDLC began in the 1960s to manage software development. It was informal in the beginning, but the need for structure led to the development of the Waterfall model in the 1970s, which introduced a sequential approach to software development.

The 1980s and ’90’s brought iterative models like Spiral and rapid application development (RAD), which focused on incremental progress and user feedback. Now, we use Agile methodologies, which improve on the former approaches.

How SDLC Works

SDLC is a framework that outlines the steps involved in developing software, which typically includes 7 phases. Each phase has its own objectives and deliverables for the project.

The SDLC can follow different models, primarily iterative or sequential. The sequential model, like the Waterfall model, follows a linear approach where each phase must be completed before moving to the next. The iterative model allows for repeated cycles of development, where phases are revisited as needed. This approach is also seen in Agile methodologies.

As for who’s involved in the process, that generally includes:

Project Managers

Oversee the project and ensure it stays on track.

Developers

Write and maintain the code.

Quality Assurance (QA) Testers

Test the software to find and fix defects.

Business Analysts

Gather and document requirements.

End Users

Provide feedback to ensure the software meets their needs.

Operations and Maintenance Teams

Make sure the software runs smoothly post-deployment and addresses any issues that arise.

Software Development Life Cycle Models

The SDLC has several models you can adopt.

Here are the most common ones.

Model	Description	Pros	Cons
Waterfall	A sequential approach where each phase must be completed before moving on to the next.	Simple, easy to manage.	Inflexible, difficult to accommodate changes.
Agile	An iterative approach that emphasizes flexibility and customer feedback. Development is done in small, incremental cycles called sprints.	Flexible, customer-focused, adapts to changing requirements.	Requires constant customer involvement, and can be less predictable.
Spiral	Combines iterative development with risk management. Each loop consists of planning, risk analysis, engineering, and evaluation phases.	Manages risk effectively, good for large, complex projects.	Can be costly and complex to implement.
V-Model	A sequential approach with a strong focus on testing. Each development phase has a corresponding testing phase.	Ensures early defect detection,and clear structure.	Rigid, like Waterfall, difficult to adapt once started.
Iterative	Involves developing software in repeated cycles, allowing for incremental improvements.	Identifies issues early, and allows for gradual improvements.	Can be resource-intensive, and requires good planning.

7 Phases of SDLC

SDLC involves 7 phases from start to finish.

Planning
Define the project scope, objectives, and goals. Gather initial requirements, identify stakeholders, set up a timeline, and estimate resources and costs.
Analysis
Assess the project’s feasibility, including technical, operational, and economic aspects. Gather and analyze detailed requirements to ensure viability and alignment with business goals.
Design
Create detailed specifications for the software, including architecture, components, interfaces, and data flow. This blueprint guides the implementation phase.
Implementation
Write the actual code based on design specifications. Developers follow coding standards and guidelines to build the software.
Testing
Verify that the software meets all requirements and functions correctly. Conduct various tests, such as unit, integration, system, and acceptance testing, to identify and fix defects.
Deployment
Release the software to the production environment. This involves installation, configuration, and user training.
Maintenance
Provide ongoing support and updates, like bug fixes, new features, and improvements based on user feedback.

SDLC Tools

Here are some commonly used tools in the Software Development Life Cycle.

Category	Tools	Description
Project Management	JIRA	Tracks tasks, bugs, and project progress.
Project Management	Trello	Organizes tasks and projects visually with boards, lists, and cards.
Development	Git	Version control system for tracking code changes.
Development	Jenkins	Automation server for building, testing, and deploying applications.
Testing	Selenium	Tool for automating web browser testing.
Testing	JUnit	Framework for writing and running Java tests.
Deployment	Docker	Platform for running applications in containers.
Deployment	Kubernetes	System for automating management of containerized applications.
Maintenance	Nagios	Monitoring tool for server and application performance.
Maintenance	Splunk	Platform for searching and analyzing machine-generated data.

7 Best Practices in Software Development Life Cycle

Involve Stakeholders Early: Discuss with stakeholders from the beginning to gather requirements and make sure their needs are met.
Implement CI/CD: Use continuous integration and continuous deployment to automate testing and deployment.
Emphasize Security: Integrate security practices into each SDLC phase to identify and mitigate vulnerabilities.
Use Agile Methodologies: Adopt Agile practices for a flexible and iterative development process.
Maintain Documentation: Keep thorough documentation at every stage. This is important for clarity, but also for future devs working on the project.
Conduct Code Reviews: Perform regular code reviews to make sure quality is high and issues are caught early.
Monitor Performance: Continuously monitor and improve the software’s performance.

Security and SDLC

You should integrate security into the SDLC to protect your apps from vulnerabilities. Each SDLC phase should incorporate security best practices.

That is, you should identify security requirements during planning, conduct risk assessments in the analysis phase, apply secure design principles, follow secure coding standards, perform thorough security testing, have secure deployment configurations, and maintain regular updates and monitoring.

SDLC Pros and Cons

The SDLC provides various benefits, but it also comes with some potential drawbacks.

Pros

Provides a systematic process for software development
Encourages clear documentation at each phase
Improves planning, monitoring, and control of the project
Helps with cross-team communication, testing, and quality checks

Cons

Traditional SDLC models aren’t very flexible, so it’s hard to accommodate changes
Can be time-consuming in the beginning stages
May not be good for projects with rapidly changing requirements

The Bottom Line

The simple software development life cycle definition is a structured framework for developing high-quality software. It involves seven phases, each with clear objectives and deliverables. This helps manage risks, control costs, and ensure that the final product meets user requirements.