Software Development Life Cycle: SDLC phases and best practices
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The Software Development Lifecycle (SDLC) is a methodology that provides a structured process for developing high-quality software in a timely and cost-effective manner. The SDLC outlines software development as a series of tasks, creating a management framework focused on efficiency and quality.
Software development is a tightly interwoven process that balances costs, deadlines, and capabilities. Through the SDLC, developers have a standardized process that defines their activities, goals, and deliverables.
What is the Software Development Life Cycle (SDLC)?
The SDLC framework defines the tasks necessary for software development. It provides a roadmap for every phase of development, from planning to long-term maintenance and support. Serving as a set of guidelines, the SDLC is not a dogmatic approach to development. It is a template teams can adapt to their unique circumstances.
Rather than trying to predict the future or constrain teams to rigid workflows, the SDLC provides an overarching structure within which teams can operate dynamically while staying on course.
The SDLC gives a holistic view that considers the whole of the end-to-end software lifecycle. This enables development teams to stay effective and on schedule even as technologies and organizations change.
Every SDLC consists of five phases:
- Planning: Defining the objectives of the project. Determining the scope, the requirements, and conducting initial design.
- Implementation: Developing the software to meet the requirements defined in the planning phase.
- Testing: Verifying that the implementation can pass software testing of its functionality and performance.
- Deployment: Deploying the software into a production environment.
- Maintenance: Providing long-term support and maintenance.
Phases of the SDLC
Here’s a detailed review of each of the five phases.
Planning
During the planning phase, stakeholders determine the project’s requirements and engineers analyze these requirements to design the most effective solutions.
The planning phase begins with gathering requirements and determining the project’s scope. To determine requirements, stakeholders provide input on their expectations from both the software and the project as a whole. These stakeholders may include customers, business leaders, managers, vendors, and developers, among other interested parties.
At this stage, organizations often conduct a feasibility study to understand the project’s potential outcomes. They also determine resource allocations and budgets for the project.
Once the requirements are understood and properly documented, the initial system and software design processes can proceed. Software engineers take the stakeholder’s requirements and develop a plan to implement them.
The engineers’ first task is known as High-level Design (HLD). During the HLD process, engineers decide what technologies to use and which tools to build with. They create a plan that maps the application’s overall architecture and illustrates how individual components will work together.
HLD is complemented by the Low-Level Design (LLD) process, which defines specific steps for creating individual components. If HLD is a blueprint for an entire multistory building, then LLD is the plan for a single room. Where HLD prepares the broad strokes of system architectures and database design, LLD focuses on the logic in individual components and other minutia.
Once the plan is in place, developers can begin writing code. This takes us to the next phase.
Implementation
In the implementation phase, developers write code to meet the requirements defined in the planning phase.
Implementation is where the project transforms from an abstract plan to a working software application.
Developers should keep the later phases of the SDLC in mind during the implementation phase. They should enforce best practices, maintain high coding standards, and ensure they use effective version control. The quality of the implementation will be thoroughly tested in later stages. Getting things right during implementation will pay dividends throughout the rest of the lifecycle.
Testing
Once in the testing phase, the application developed during the implementation phase is subjected to automated and manual testing. This phase verifies that the software meets the requirements from the planning phase and is performant enough to be deployed to a production environment.
Software testing verifies that individual pieces of code work as intended through methods such as unit tests. Other methodologies like integration and system testing verify that the application behaves as expected when all its components operate together. The testing pyramid model incorporates these techniques into a robust testing process.
Another context for testing is Quality Assurance (QA). QA teams perform manual testing to ensure applications meet requirements. They also hunt for bugs, replicate how users interact with the application during normal usage, and provide feedback on the quality of the implementation.
Deployment
The deployment phase involves packaging the application for release and deploying it to a production environment. Once deployed, the application will be available for users and customers.
Throughout the implementation and testing phases, developers work on a private version of the application in development environments. This differs from the production version that will be deployed for end users.
In the case of a service application, the application is migrated from the development environment to a production environment that utilizes infrastructure capable of accommodating the load from user traffic.
During deployment, developers carefully monitor the application’s performance to ensure it behaves as intended. While thorough testing should eliminate most surprises, there may be unexpected issues or fine-tuning steps to complete while deploying.
Maintenance
The final stage of the SDLC is maintenance: updates, patches, bug fixes, and ongoing support for service applications.
Depending on the type of application, maintenance may be regular or infrequent. Some stable applications only release patches to address major bugs or add new features. Other applications constantly make small incremental improvements in response to user feedback. Understanding what your users need and expect from your application over the long term will enable you to estimate the resources necessary to support the project.
Importance of Each SDLC Phase
The real value of the SDLC comes from each phase setting up the next phase for success. This necessitates that goals and requirements are clearly defined throughout the lifecycle.
Skipping a phase, or underestimating a phase, is sure to incur an unnecessary technical debt.
By creating clear requirements in the planning phase, developers can begin writing code in the implementation phase with tangible goals. The team understands where the finish line is, helping to avoid scope creep. They work from the HLD and LLD specifications until they have a functional application that meets the stakeholders’ requirements.
The testing phase validates the work done during the implementation phase. Testing enforces the requirements of the planning phase and verifies the implementation’s quality. Comprehensive testing provides assurances that the application is ready for deployment. During deployment, DevOps teams are well-prepared to expose their code and infrastructure to real users.
Incorporating the maintenance phase into the lifecycle ensures the application remains useful, performant, and up-to-date as long as possible. Maintenance and scaling requirements are key considerations during the planning and implementation phases, helping to minimize any hidden surprises in the application’s lifecycle.
Benefits of a well-defined SDLC
A well-defined SDLC is a strategic plan created at the project’s earliest stages and adhered to throughout its entire lifecycle. Specific benefits of a great SDLC plan will be unique to each team, but some general goals of a well-defined SDLC include:
- Improved project management and control: The SDLC provides requirements and design specifications up front, helping to set clear goals and simplify project management.
- Better resource allocation and risk management: The forward-thinking SDLC approach proactively addresses potential risks and helps forecast resource requirements.
- Higher quality software and customer satisfaction: The SDLC’s ultimate goal is to produce high-quality software that meets or exceeds the stakeholder’s requirements.
- Enhanced security: Being cognizant of the full lifecycle of the application allows for a proactive approach to eliminating security risks. Rather than addressing them as an afterthought at the end of the development cycle, developers can assess potential vulnerabilities and account for them during implementation and testing. This is a core component of the shift-left philosophy of DevSecOps.
Measuring effectiveness of the SDLC
An effective SDLC strategy is more than just an abstract plan. There are key metrics to assess the performance of the SDLC and its phases. These include:
- Project completion time: The overall project duration from start to finish and the duration to complete specific milestones within the development lifecycle.
- Budget adherence: How closely the project’s actual costs match initial projections.
- Defect rates: The number of bugs and errors in the application.
- Customer satisfaction: Data from real-world users assessing their satisfaction with the quality of the application.
Challenges of implementing the SDLC
Many major challenges come during the planning phase. If stakeholders cannot effectively communicate their requirements, this can lead to serious issues during the implementation phase. Shifting requirements throughout the project is a surefire way to complicate development and introduce scope creep.
Other challenges can come from discounting the importance of certain phases, especially testing and maintenance. Failing to give these phases their due can lead to delays, cost overruns, and low-quality applications.
Integrating CI/CD into the SDLC
Continuous integration and continuous delivery (CI/CD) is an approach to software development that combines two powerful methodologies: continuous integration (CI) and continuous delivery (CD) . CI/CD concepts and tools are indispensable assets throughout the SDLC.
CI simplifies merging code changes from multiple developers. CI tools automatically integrate, build, and test new code, reducing the burden on developers to complete these tasks manually. With CI, workflows for updating and testing code are efficient and developer collaboration is streamlined.
By emphasizing the importance of testing and relying on CI tooling to automate the build and test process, CD ensures new code is always ready to be deployed. This allows teams to deploy with minimal manual intervention while maintaining high code coverage and quality.
CI helps substantially during the implementation and testing phases by automating code integration, building, and testing. CD further streamlines the testing and deployment phases by ensuring that new code is always ready for testing or production purposes. Both CI and CD assist in the maintenance phase by simplifying the process of making and deploying changes.
Benefits of CI/CD in the SDLC
CI/CD assists developers with the practical work of building an application. The benefits of a CI/CD pipeline are most pronounced in the Implementation, Testing, Deployment, and Maintenance phases.
Once developers are writing code, CI/CD provides very tangible benefits for the SDLC:
- Faster delivery cycles: CI/CD ensures that code is continuously integrated, built, tested, and ready to deploy, boosting the velocity of delivery cycles.
- Improved code quality: CI/CD tools and best practices excel at enhancing code quality by simplifying developer collaboration, automating testing, and making it easy to change and improve code.
- Increased developer productivity and satisfaction: Reducing developers’ toil from performing repetitive tasks, CI/CD empowers developers to focus on innovation and problem-solving. This leads to happier and more productive developers.
Conclusion
A structured SDLC is a sure foundation for any software development project. Understanding the SDLC helps teams strategize the most efficient path to creating high-quality applications.
Planning for the application’s entire lifecycle helps to set expectations, allocate resources, and design the most effective solutions. It simplifies project management and helps development stay on schedule. Creating opportunities for developer success boosts team morale and developer productivity. These factors all blend into better software.
Combining the principles of the SDLC with robust CI/CD is a recipe sure to boost the speed of development cycles. The tools and methods of CI/CD complement the SDLC philosophy, helping developers do their best work during implementation, testing, and beyond.
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