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SDLC Unveiled: Essential Guide to Software Development Life Cycle
Unlock the key phases of software creation with our deep dive into the software development life cycle. Navigate the nuances from planning to maintenance.
14 Min Read
Alamy
At a Glance
- The SDLC breaks software development into seven stages to structure the development process systematically.
- The SDLC is a repetitive process, where development teams continuously cycle through the stages even after deployment.
- New trends like agile, DevOps, and cloud have reshaped the SDLC, offering more flexibility, collaboration, and efficiency.
At first glance, the software development life cycle, or SDLC, may seem like a pretty simple concept. It describes the set of processes that developers work through to create software.
But if you dive more deeply into the SDLC, you're likely to realize that it's actually a very complex topic. Questions like which SDLC models to use and how to implement SDLC processes can be tough to answer.
This guide to the software development life cycle offers some insights. Not only does it cover what the software development life cycle is and why it's so important in the realm of modern software development, but it also describes the key stages of the SDLC, different SDLC models, and how the SDLC relates to other software development trends, like DevOps.
Demystifying the Software Development Life Cycle
The SDLC as an Iterative, Repetitive Process
Importance of SDLC in Modern Software Engineering
Stages of the Software Development Life Cycle
Agile vs. Traditional SDLC Models
Best Practices for Effective SDLC Implementation
Future Trends: Evolving with the SDLC
FAQs on Software Development Life Cycle (SDLC)
Introduction to SDLC
The software development life cycle is the set of processes that software developers use to create and update software. Although the exact procedures that developers follow will always vary from one project or team to another, the SDLC refers to a core set of processes that are at the heart of virtually all modern software development initiatives.
The origins of the SDLC trace back to the 1960s, when engineers first began talking about the "systems" development life cycle. As we explain in more detail below, however, the SDLC concept has changed significantly over time as new strategies and models — such as agile and DevOps — have emerged.
Demystifying the Software Development Life Cycle
Although the SDLC might seem like an abstract concept at first, its basic tenets are pretty straightforward. The SDLC breaks software development operations into seven basic stages:
Planning: The SDLC starts with developing a plan for which application features to implement, as well as considerations like overall application architecture.
Analysis: During the analysis phase, developers determine which resources they'll need to implement software based on the plans they devised.
Design: The design phase focuses on defining technical details for the product — in other words, translating the high-level plans and analyses performed earlier in the SDLC into a technically specific design.
Coding: During the coding phase, developers write the code necessary to implement the application they've designed.
Testing: Software testing allows developers to validate that the application performs as expected. Testing may also include scanning for security risks.
Deployment: Deployment is the process of moving a newly built application from the environment where it was built and tested into a production environment where it is accessible to end users.
Maintenance: The maintenance phase includes all of the work necessary post-deployment to keep an application operating normally — such as monitoring for and responding to application performance issues.
We'll discuss each of these stages in more detail later in this guide.
The SDLC as an Iterative, Repetitive Process
In most cases, the SDLC is an iterative process: After developers work through each of the stages described above, they begin working on a new set of application updates, which they'll implement by working through each stage of the SDLC once again.
Thus, reaching the maintenance stage of the SDLC doesn't mean that the SDLC is over. It just means that one version of an application is up and running, and that developers are now ready to begin work on another round of application enhancements.
Importance of SDLC in Modern Software Engineering
The main reason why the SDLC is important for modern software engineers is that it provides a consistent, systematic approach to application development.
Historically, before the SDLC became a widely embraced concept in the world of software development, software engineers lacked a rigid structure for approaching the software development process. They also lacked a consistent language for thinking about and describing the various stages that software went through as it evolved from an idea into a running production application.
The SDLC solves these challenges by offering a universal framework for thinking about and organizing software development projects. As we explain in more detail below, there are varying SDLC models and strategies; in other words, different teams "do" the SDLC in different ways. However, the SDLC serves as a foundational baseline that helps guide the way that virtually all of today's developers conceive and structure the process of software development.
Stages of the Software Development Life Cycle
Now that we've covered the basics of the what the SDLC means and why it's important, let's examine each of the stages of the SDLC in depth.
1. Planning: The Project Conceptualization Stage
You can't build software very effectively if you lack a concrete idea of what you actually want to build — which is why planning is the first critical stage in the software development life cycle. Planning allows developers to set high-level goals for the application they're building.
At this stage, the ideas don't require a great deal of technical specificity. The focus during the planning stage should be on what you want to do, not exactly how you'll do it — that comes later.
That said, planning can be an opportunity to think about very high-level technical considerations — such as, again, which type of basic application architecture developers will use.
2. Analysis: Identifying Development Requirements
After deciding what they want to do as they build an application or application update, developers can determine what they'll need to do it. This is the purpose of the analysis phase of the SDLC.
During this stage, developers should answer questions like how many coders they'll need to build the features they have planned, as well as which software tools they'll rely on. They should also consider potential conflicts — like the risk that personnel they expect to depend on are already bogged down by other projects — so that they can get ahead of them.
3. Design: Getting Into Technical Details
The design stage of the SDLC is perhaps the most ambiguous. Despite its name, the purpose of the design stage is not specifically to design an application interface or layout (although this may be one aspect of the design phase).
Instead, developers should use the design phase to establish and document technical details about how they'll implement the software features or capabilities they have in mind. This includes answering questions like which programming languages or frameworks they'll use, as well as how the various components of their application will interact.
4. Coding: Translating Ideas to Action
The coding stage is arguably the most straightforward part of the SDLC. It's the step during which developers write the code necessary to implement the functionality they have planned, based on the technical specifications they established during the design phase.
That said, coding can be a complex stage in the SDLC, especially if the project requires a large number of engineers to write code at the same time. In that case, it's important to ensure that coders communicate effectively, and that they are able to integrate their code efficiently into a central codebase using modern CI/CD tools. Otherwise, developers are at risk of becoming bogged down by conflicts within code or redundant code.
Maintaining code quality standards, too, should be a focus during the coding phase. Developers should strive to write code that not only do they understand, but that is also easy for others to read — now and in the future.
5. Testing: Ensuring Quality and Security
Testing can seem like a mundane or boring phase of the SDLC, but it's an absolutely critical one. Testing allows developers to detect and fix problems in their software prior to deploying it.
There are multiple types of tests that can occur during this stage, including:
Performance tests, which validate that an application can meet goals such as responding quickly enough to user requests.
Load testing, which checks how well an application performs when it is under varying levels of load.
Security tests, which scan for issues like code injection risks and known vulnerabilities within an application's codebase.
Developers can perform tests manually. However, to operate efficiently and keep the software development life cycle moving, most teams today make extensive use of automated software testing tools.
6. Deployment: Putting Code Into Production
Making a new application or application version available to users requires moving it into a production environment. This takes place during the deployment stage of the software development life cycle.
In some cases, deployment is straightforward: Developers simply copy the application they've built into a hosting environment where end users can interact with it. However, this process is not always so simple. Problems may arise due to issues like inconsistencies between the configuration of the development environment and the production environment, resulting in unexpected application behavior.
To help mitigate these risks, developers can leverage strategies such as blue/green deployments and canary releases. These practices help teams transition apps to production environments more gradually, reducing the risk that a problem during deployment will cause trouble for a large number of end users.
7. Maintenance: The Final Frontier
Even when an application passes all of its tests and deployment proceeds without a hitch, a variety of problems may arise once the app is up and running in production. Spikes in user traffic could lead to performance degradations, for example, or bugs that testing failed to detect may cause the app to crash.
The maintenance stage of the software development life cycle protects against risks like these. During this stage, engineers watch for problems in production and respond when they arise.
Maintenance work may fall to the same developers who wrote an app, especially when organizations embrace a DevOps approach to software delivery. In other cases, however, maintenance is the responsibility of a separate IT operations team.
Agile vs. Traditional SDLC Models
As we mentioned, all SDLCs include the same core procedures, but there are multiple models available for implementing those procedures.
At a high level, there are just two main types of SDLC models:
As we mentioned, all SDLCs include the same core procedures, but there are multiple models available for implementing those procedures.
At a high level, there are just two main types of SDLC models:
Waterfall, a traditional approach that focuses on implementing SDLC processes sequentially. Under this model, a new process cannot begin until the one preceding it is complete.
Agile, a more modern SDLC model that emphasizes rapid, continuous change, as well as parallel processes.
Within each of these categories, there are multiple frameworks that include more detail on precisely how to build an SDLC based on a given model. For example, if you choose an agile model, you could opt to implement it using an approach like Kanban or Scrum.
Best Practices for Effective SDLC Implementation
By simply embracing the software development life cycle as a foundation for structuring the software development process, teams gain coherence and consistency for complex development operations. However, to get the very most from the SDLC, they should consider additional steps, such as:
Invest in security: Ideally, security should be integrated into all stages of the SDLC — from planning, when developers should think about how their goals impact potential application security risks and exposures, through to maintenance, when monitoring for active threats should be part and parcel of the broader maintenance process.
Strive for consistency: Ensuring that all engineers approach the SDLC in a consistent way can be challenging, especially when working with large teams. Different programmers may prefer different coding styles and tools, for example, leading to inconsistency. Although allowing some degree of flexibility is important, it's also a best practice to establish overall guidelines that help ensure that all project participants work in the same basic way.
Use version control: Version control tools don't just help developers keep track of changes to code over time. They're also invaluable in situations where engineers need to revert to an earlier version of an application or feature to fix a bug.
Document everything: While writing documentation may not be at the top of most developers' list of good times, documenting everything that happens within the SDLC ultimately makes software engineers' lives easier. Documentation should include not just a description of how software works, but also why developers built resources in the way they did and how components have changed over time. This insight will help engineers operate efficiently over the long term.
Set realistic goals: To keep the SDLC efficient, it's important to set manageable goals. Teams should avoid trying to implement too many new features at once or setting application performance objectives that they can't feasibly meet. Otherwise, they're likely to find their SDLC operations hampered by delays and disruptions due to misalignment between what they want to do and what they are actually capable of doing.
Future Trends: Evolving with the SDLC
Although the SDLC concept has been around for decades, it continues to evolve.
The introduction of the agile concept in the early 2000s was one major change. As noted above, agile encourages a more efficient and flexible approach to implementing software development processes.
More recently, trends like DevOps have exerted a major impact on the SDLC. By emphasizing collaboration between the engineers who write software and those who maintain it once it's in production, DevOps aims to avoid the conflicts and inefficiencies that can arise when each group lacks visibility into the other group's priorities and challenges.
Likewise, DevSecOps, which encourages the integration of security into all stages of the SDLC, has helped push modern development teams to make security a top priority when designing, implementing, testing, and maintaining applications. Historically, most teams treated security as a separate, siloed process — an approach that was not only inefficient but also increased the risk that engineers would fail to detect critical security risks prior to deploying an application to production.
Cloud technology, too, has had an important impact on the SDLC. The cloud moved many application development and hosting processes into cloud-based environments, where they are easier to scale — and where collaboration is simpler because all engineers can work with the same cloud-based tools and code.
In addition, containers — which can run on-prem or in the cloud — have helped make some parts of the SDLC more efficient and less risky. Containers do this by providing a consistent environment for developing, testing, and deploying applications, which reduces the risk of problems due to inconsistent environment configurations between different stages of the SDLC.
It's impossible to say what the next big thing will be in the realm of the SDLC, but what is clear is that the software engineers are always coming up with new concepts and practices to bring greater efficiency to the overall process.
FAQs on Software Development Life Cycle (SDLC)
What Are the Core Objectives of SDLC?
The main goal of the SDLC is to provide a consistent, repeatable means of structuring software delivery operations. In addition, the SDLC offers a common set of concepts and terms that all software engineers can use to think about and discuss the work they perform.
How Can Businesses Choose the Right SDLC Model?
There is no single "best" SDLC model. To identify the right model for their needs, businesses should consider factors like how many developers will be working on a project, since coordinating work between a large number of coders may require more sophisticated SDLC models and tools. They should also assess how quickly they want to release software and how often they'll update applications.
In general, most software engineers consider agile models to be the more modern and preferable type of SDLC model today. That said, waterfall may be a more appropriate choice for simple, small projects that don't require the complex organizational structure of agile.
What Role Does Feedback Play in the SDLC Processes?
Feedback — meaning information about challenges and successes that arise during the SDLC — provides insights that help engineers improve the efficiency and reliability of SDLC operations over time. For instance, feedback about problems identified during the maintenance stage of the SDLC allows developers to determine which changes they should make to an application to avoid the issues in a future release.
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