Software Development Lifecycle (SDLC)

Software development lifecycle is a step-by-step process used to design, create, and test software. The software development lifecycle or SDLC gives an organized roadmap to the software development team to produce a high-quality product that meets user needs. The software development lifecycle (SDLC) main goal is to produce high-quality maintainable products which are cost and time-effective. There are 7 phases of the software development lifecycle. Each software development life cycle phase outlines the detailed development plan. Every phase of SDLC helps the development team perform each task efficiently to produce high-quality products within a given timeframe, by keeping in mind the budget constraints. In this article we will explore key insights into how the software development lifecycle (SDLC) works, along with its key benefits and challenges.

What is SDLC?

Software development lifecycle is a process used to build high-quality maintainable software products. SDLC consists of phases that precisely describe how to create, design, develop, maintain, replace, and enhance the quality of software that meets user needs. The SDLC not only defines the method for improving software quality but also helps the development team efficiently deliver each milestone within a specific time frame.

Software Development Life Cycle Phases

There are 7 stages of the software development life cycle (SDLC). Each phase of SDLC ensures the end product meets the user’s needs within the budget. The 7 phases of SDLC are as follows:

1. Planning

Planning is the first step in the software development life cycle. It’s the most crucial step of SDLC as it lays the foundation for an entire software project. At this stage the team gathers to brainstorm, and define the scope, objective, requirements, and resource allocation of the project. This phase ensures that the development plan is well structured and aligned with business goals.

2. Requirement Analysis:

The requirement analysis phase is a crucial step in SDLC. It’s the process of gathering, analyzing, and documenting what a system or product must do to meet user and business needs. Which involves the following steps:

• Understanding stakeholders needs
• Identify functional and non-functional requirements
• Validating the requirements
• Prioritizing the requirements

All the details are documented in an SRS (Software Requirement Specification), which serves as a foundation for the development process.

3. System Design:

This phase includes the designing of software architecture based on the requirements gathered during the planning phase. In this phase, the software development team creates a detailed structure and design of the software product. This includes high-level architecture and detailed design specifications such as how the user interface will look and work to ensure the software is easy to use or user-friendly.

(Note: Compatibility with existing system is also assessed)

4. Implementation:

This is the most crucial phase of the SDLC as the design is transformed into functional requirements. That’s why this phase is also called the development phase. In this phase, developers write the code based on design specifications, following best practices and coding standards to ensure the result is efficient, secure, and maintainable. Different programming languages are also used in this phase such as Python, Java, C++, C#, etc. as per software regulations. Some conventional programming tools are also used like compilers, debuggers, code interpreters, etc.

5. Testing:

The testing phase is a critical step of SDLC to ensure the quality and reliability of the software. In this phase, developed software is thoroughly tested to identify and fix defects or issues. The key aspects of the testing phase include:

Key aspects of the testing phase include:

• Validation and Verification: Ensures the software meets the specified requirements and functions as intended.
• Types of Testing: Includes various types such as unit testing, integration testing, system testing, and user acceptance testing (UAT).
• Bug Identification and Fixing: Any defects found are logged, resolved by developers, and re-tested.
• Performance Testing: Evaluate how the software performs under different loads and conditions.
• Security Testing: Identifies vulnerabilities to ensure the software is secure against threats.
• Automation and Manual Testing: Uses automated tools or manual methods for effective testing depending on the project’s needs.

The goal of this phase is to ensure that the software is error-free, performs well, and is ready for deployment. It also helps in building confidence that the software will meet user expectations.

6. Deployment

After testing the software product or solution is moved to production and can be deployed to end users. This includes planning, setting up the system, testing, moving data, and launching the product. After deployment, the team checks everything is working, provides training if needed, and shares any important information with users or stakeholders. Monitoring the system and fixing any problems quickly is important. Clear plans, good communication, and using tools to automate the process help make the deployment smooth and successful.

7. Maintenance

Maintenance is the last phase of SDLC. After the successful deployment, the product is monitored for ongoing support to address issues, software updates, and adding new features. Continuous maintenance ensures that the software remains functional and relevant over time.

Common Software Development Life Cycle Models

Some of the most common software development lifecycle (SDLC) models include:

Waterfall

Waterfall is the fundamental model of SDLC. It is the most straightforward model which follows a linear approach to software development. In the waterfall model, each phase must be completed before the next one begins. All the software development phases occur in sequence and the software development team can not go back to the previous step, modify or make any changes. That’s why it is called the waterfall model as once the waterfalls it can not go back.

In which situation a waterfall model is used?

Best for small projects with clear and minimal requirements

Agile Model

The Agile model follows an iterative approach and facilitates quick project completion. It focuses on flexibility, collaboration, and iterative progress. It emphasizes breaking down tasks into small, manageable units continuously improving through frequent feedback and adaptation known as “sprints”.Agile methodology focuses on defined roles such as Scrum Master, Product Owner, and Team) and regular sprints.

When should the Agile model be used?

Agile is best suited for complex projects where requirements  frequently change.

Iterative Model

As the name shows, the iterative model divides the project into small, repeated steps. Instead of completing the entire project in one go, teams work on smaller parts, test them, and improve them based on feedback before moving on to the next step. This process continues until the final product is ready. It allows for adjustments along the way, making it easier to fix issues and meet user needs effectively.

When to use an Iterative Model?

The iterative model is best suited for when the software application is large, requirements may change in the future, and requirements are not clear but easy to understand.

V-Model

The V-model is also known as the Verification and validation model. It follows a sequential and systematic approach with corresponding testing phases for each development stage. It forms a V shape, where the left side represents development activities (e.g., requirements analysis, design, implementation), and the right side corresponds to validation phases (e.g., unit testing, integration testing, system testing). Each development stage is directly linked to a testing phase, ensuring defects are identified early and alignment with user requirements is maintained.

When to use V-Model?

This model is best suited for projects with well-defined requirements and a strong focus on testing.

Spiral Model

It is one of the most crucial models of SDLC as it follows both iterative and incremental approaches that provide support for risk handling. The four key phases of the spiral model are planning, risk analysis, engineering, and evaluation. These steps are repeated in spiral format fo

r continuous refinement. Each loop in the spiral helps the development team identify defects or issues earlier. The model provides thorough validation at each stage.

When will the spiral model be used?

The spiral model is best suited for high-risk projects with evolving requirements.

Software Development Model Selection Based on Project Requirements

Following are the key factors to consider while selecting a software development model:

Criteria	Recommended Models
Requirements	Clear and Stable: Waterfall, V-Model Changing/Evolving: Agile, Iterative
Project Size and Complexity	Small Projects: Waterfall, RAD Large Projects: Agile, Spiral, DevOps
Team Expertise	Experienced Teams: Agile, Scrum Less Experienced Teams: Waterfall, V-Model
Client Involvement	Frequent Feedback: Agile, Scrum, RAD Minimal Involvement: Waterfall, V-Model
Time and Budget Constraints	Fixed Time/Budget: Waterfall, V-Model Flexible Time/Budget: Agile, Spiral
Risk Management	High Risk: Spiral Low Risk: Waterfall
Product Release Timeline	Quick Release: Agile, RAD Long Development Time: Waterfall, V-Model
Maintenance and Support	Long-Term Maintenance: Agile, DevOps Minimal Maintenance: Waterfall, V-Model
Stakeholder Expectations	High Engagement: Agile, Scrum Low Engagement: Waterfall, V-Model

How does SDLC address security concerns?

Security is one of the primary concerns in software development. A software development life cycle or SDLC addresses security concerns through DevSecOps practices. DevSecOps is an extension of DevOps that ensures the security concerns throughout the entire SDLC phases.

DevSecOps is the practice of adding security testing at every stage of software development. It ensures that the software is secure from the initial to the final phase of SDLC. During DevSecOps security assurance activities are performed including code reviews, architecture analysis, and penetration testing to find vulnerabilities that hackers could exploit. DevSecOps helps the software development team to find bugs and issues earlier and build more secure software. That’s why it is also called “Secure SDLC”.

How SDLC works: Real-life example

Let’s take a real-life example of developing an eCommerce website using SDLC:

Phase	Description	Key Activities
1. Planning	Define project goals, scope, and security requirements.	– Gather requirements from stakeholders. – Define project scope, timelines, and budget. – Identify security needs (e.g., SSL, encryption).
2. Requirement Analysis/Feasibility study	Assess the project’s viability in terms of cost, time, and resources.	– Conduct feasibility study (technical, operational, and financial). – Determine the project’s risks and possible challenges. – Approve project plan.
3. Design	Plan the system architecture, UI/UX, and security features.	– Create wireframes and design UI. – Plan back-end architecture (database, servers). – Design security features (e.g., secure login, payment gateways).
4. Development	Build the actual product by coding the website’s features and integrating security measures.	– Develop front-end and back-end code. – Implement security measures like HTTPS, data validation, and encryption. – Set up databases and payment gateways.
5. Testing	Ensure the product works as expected and meets security standards.	– Perform functional testing (features, usability). – Conduct security testing (penetration tests, vulnerability scans). – Test payment processing.
6. Deployment	Deploy the website to the live environment and make it available to users.	– Deploy to the production environment. – Configure the server, database, and security features. – Finalize user access and authentication setup.
7. Maintenance	Continuously update and monitor the website for bugs, performance, and security issues.	– Monitor performance and user feedback. – Apply security patches and software updates. – Fix bugs and optimize the site as needed.

Conclusion

In conclusion, the Software Development Life Cycle (SDLC) is crucial for creating software that meets user needs effectively. It ensures a structured, organized approach to development, resulting in reliable and high-quality products.