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Software Development Lifecycle (SDLC): Phases, Process, Models & Best Practices

Even though the technologies used to build software continue to evolve at a dizzying clip, the philosophies that guide software development teams when taking a project from idea to final product have remained steadfast.

This article examines the Software Development Lifecycle (SDLC): Phases, Process, Models and Best Practices to provide an idea of how software gets made.

The Software Development Lifecycle Explained

The software development lifecycle is a set of business practices and procedures that software development teams follow when building software. When done right, the team is able to produce excellent software in the shortest possible time and at a low cost. Additionally, the final software will meet the client’s expectations and solve the end-user’s problem.

What Is the Purpose Of SDLC

Generally, development teams outline the tasks required to build a software program. The main goal is to prevent the waste of resources and make the development process as efficient as possible. Additionally, project managers ensure that the project stays on track.

Typically, the software development life cycle is divided into several steps, which may include information gathering, planning, design, implementation, testing, deployment, and maintenance. Depending on the size and scope of the project, the above steps may be combined or one or two omitted.

SDLC Origins

During the 1950s and 60s, the field of computer science saw rapid advancements that led to the beginnings of a production framework. Over time, the framework went through numerous changes that evolved to the SDLC used to make modern software.

Prior to the 1960s, there wasn’t any need for a structured means of developing software since the computing field was still in its infancy. However, once programming grew in complexity, so did the need for structured programming.

SDLC Importance

The SDLC is important for the following reasons:

  • It helps teams plan efficiently and effectively
  • It allows project deliverables to be tracked
  • It speeds up the development process
  • It provides visibility of projects to all stakeholders
  • It helps to strengthen client relations
  • It minimizes project risks
  • It’s an excellent cost saver

The 7 Phases of SDLC

As mentioned above, software development goes through several phases. Let’s examine each one in more detail.

Requirement Gathering and Analysis

During this phase of development, developers collect the information needed to develop the product from the client. It’s important that both parties are clear about what the final product should do, so there shouldn’t be any ambiguity.

A representative of the software development company (usually the project manager) arranges a meeting with the client. The aim of the meeting is to get a complete picture of the client’s expectations concerning factors such as the problem being solved by the software and the intended end-user of the product, among others.

After all the information has been gathered, the brief is analyzed to determine how feasible it’ll be to develop it into a product. Where there are points that need further elaboration or clarification, the company will set up another meeting to hash out the details.

When the software development company receives all the details, it creates a document called the Software Requirement Specification (SRS). The developers and the client will use this document as a reference and road map as the software development progresses.

Planning

The planning phase of software development involves a thorough evaluation of the project. At this phase, the development company estimates the cost of labour and materials, draws up a schedule, sets targets and deadlines, and puts the team together.

Additionally, the development company gets feedback from stakeholders such as potential product users, industry experts, and the like. In other words, this stage aims to get a clear picture of the scope of work, keeping the team focused while preventing the project from going off the rails. Project managers may also identify risks to the project and set quality assurance requirements.

Design

At this phase of software development, the developers use the information gathered in the SRS document to develop a design plan. The design plan then guides the implementation phase of the development process.

Typically, the team creates design documents and coding guidelines during this development phase. Additionally, they may have meetings to determine the tools, frameworks, and runtimes required to complete the job and meet the client’s expectations.

Common aspects of development hashed out during the design phase include:

  • Software Architecture: The team selects the programming language they’ll use to code the software and industry practices they’ll follow during the coding process.
  • User Interface Design: This determines what the end-user will see when they launch the software application and how they’ll interact with it.
  • Platform Selection: This will determine which software platforms the software will run on. Well-known examples of software platforms include Windows, iOS, and Android.
  • Programming: It defines how the program will solve problems and perform tasks.
  • Application Communications: This determines whether the application will need to communicate with other applications and how.
  • Security Precautions: These determine how the team will keep the software secure from malicious cyber actors like hackers. User credentials like passwords and credit card details are examples of data collected by software that’ll need safeguarding.

Also, depending on the SDLC model used, development teams may build a prototype of the software.

The aim of building a prototype is to demonstrate to the client what the software will look like and eventually work. Additionally, it saves costs because it’s easier to make changes to a prototype than to deal with rewrites when the software development has progressed.

Implementation

Implementation involves writing the software program’s source code using a programming language. A single developer may work on a small project while the work on bigger projects is divided between team members.

Additionally, software development teams use version control systems to keep track of changes made to the code base. Also, some team members are tasked with preparing the software’s documentation, i.e., the instructions explaining how to use it and its various features.

Testing

The software is tested after the implementation or coding phase. The primary aim of this phase is to catch any existing bugs (errors) in the software. If bugs are found, the developers are tasked with fixing them. Anything that negatively impacts the customer experience is neutralized during this software development phase.

Additionally, developers may rely heavily on the SRS document to make sure the software works as intended and is in line with the client’s expectations. Meanwhile, developers may manually test the software or automate the testing process.

Deployment

Once the developers finish testing the software, they’ll deploy or release it to the final end-user. Sometimes, User Acceptance Tests are run so the client can confirm the software works to their expectations before it’s released.

Generally, the deployment of software is automated. Examples of automated deployment include setting up a payment portal on a website or allowing the application to be downloaded onto a device. Additionally, the Development Operations engineers on the team may use software to monitor the application’s performance while it’s out in the wild.

Maintenance

Once the software reaches the end-user, the developers switch to maintaining the product. Maintenance entails fixing bugs not patched before launch, taking care of issues reported by end-users, and implementing post-deployment changes, among others. Typically, the larger and more complicated the software, the longer the maintenance period.

Outside of fixing bugs, teams may plan new features for the software during the maintenance phase. These features may come in the form of regular updates to the software, with some of the features developed stemming from ideas proffered by team members internally, while others may be based on feedback from users.

SDLC Models

Below, we’ll discuss the various software development lifecycle models that development teams use to deliver software products.

Waterfall Model

The waterfall model is a linear model for developing software. The project progresses as one phase leads into the next. For example, when the developers hit a milestone, work stops and they test the project for bugs before moving on to the next phase.

The waterfall model’s main benefit is that it allows the team to stop at a predetermined point and evaluate the work done for feasibility and continuity before progressing to the next. However, the disadvantage of this model is it can be quite slow going because until one phase is complete, no progress gets made.

Agile Model

As the name suggests, speed and flexibility are at the heart of the agile software development model. Here, the developers build the software bit by bit in a series of release cycles instead of taking a linear “start to finish” approach.

The agile model gives developers the opportunity to make incremental changes and improvements to the software on an ongoing basis. As they release a new version of the software, they can collect feedback that’ll be used as input for the next version. This approach’s disadvantage is that reliance on feedback may take the project off track.

V-Shaped Model

The “V” in the V-model stands for verification and validation. This SDLC model shares similarities with the waterfall model in that it takes a linear approach to software development. At each stage of development, the developers test the software to catch and fix bugs before moving to the next.

Big Bang Model

When the client doesn’t have a clear vision of what their final product should do, developers can use the big bang model for developing software. However, the big bang model is incredibly loose, following no set structure or guideline. Therefore, it’s best used for smaller projects or internal experiments.

Iterative Model

Like the agile model, the iterative model doesn’t use a linear approach to build software. Instead, the developers create an incomplete version of the application, adding more functionality with each iteration. So, by the time the developers reach the final iteration, all the software’s requirements (functionality) will be implemented.

Spiral Model

Repetition is the driving force of the spiral model. Within this model, the software development team takes a software product through planning, design, building, and testing over and over again, making incremental improvements each time. The model gets its name from the cyclical nature of the development process.

Prototype Model

The prototype model focuses on building a prototype to get feedback from the client. When the developers receive feedback, they implement it into the prototype and send it to the client for more feedback. Only until the prototype meets the client’s requirements is the actual software built.

Software Development Best Practices

Below are some best practices that’ll make the software development lifecycle smooth for everyone involved.

Effective Communication

Effective communication can be the difference between a development lifecycle that progresses according to schedule and one with delays and budget overruns.

Therefore, it’s important that the development team manage the client’s expectations from the onset while simultaneously communicating what’s possible.

Collect Feedback

Feedback collection is the backbone of most of the SDLC models mentioned above. It’s extremely important because it can save time, effort, and money spent on building something the end-user doesn’t want.

Additionally, getting feedback from the client will help keep the project in line with their needs for the software.

Frequent Testing

Testing is at the heart of every model mentioned above. While some models test the software when they reach a milestone, others rely on feedback from stakeholders to develop a good product. So even though errors are bound to crop up in the final software, frequent testing will help keep them to a minimum.

Conclusion

To recap, the software development lifecycle is a set of business practices and procedures commonly used by software development teams to guide the development process.

Software development typically goes through several phases, including information gathering, implementation, and testing. The way teams move through each phase is referred to as the software development model.

No matter which model a development team uses to build software, the end goal remains to meet client expectations and solve end-user problems.

Stavros Zavrakas

Since a very young age, Stavros has been passionate about the power of technology which pushed him to study Computer Science at the University of Crete. Throughout his career, he worked as a full-stack software engineer and lead developer and acted as a mentor tackling challenging IT problems of various industries - from healthcare to publishing.

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