What Is the Software Development Lifecycle?

The software development lifecycle (SDLC) is a process that development teams use to build high-quality software efficiently and cost-effectively. It involves several steps teams can follow to build software in a predictable and orderly manner.

How does the SDLC work?

The SDLC is organized into distinct phases, enabling teams to build software in a high-quality and consistent manner. Think of it as a virtual assembly line for software products. While every organization has a unique approach to software development, many tend to think of the SDLC in the following stages:

Plan

In this stage, teams scope out software requirements thoroughly. They leverage resources such as customer insights, market research, internal subject matter experts, and external stakeholders to create a concrete plan. During this phase, development teams aim to lay out the following details:

• Resource allocation
• Cost analysis
• Project schedule
• Specific objectives
• Software requirement specifications (SRS)

Then, they must present the above requirements to the correct stakeholders for approval.

Design

Next, the developers take the requirements they devised in the first phase and build the architecture for creating the product. In this stage, they put together a Design Document Specification (DDS), specifying the tools they will leverage and how these technologies will integrate with existing tech stacks.

Implement

The developers then move into the implementation stage, writing the code that eventually becomes the final product. They break the overall requirements into smaller units, which become their daily tasks until the entire project is built.

Several programming tools, such as compilers, interpreters, and debuggers, enable the developers to build code snippets on individual machines. The developers then commit these individual pieces to a central repository where they fit together to make up the complete product.

Test

Next, the development team tests the quality of their product with a mix of automated and manual testing. They test for quality and functionality, ensuring the product meets the standards and requirements outlined in earlier stages. Teams often create software documentation at this stage, ensuring that future teams can quickly get up to speed on maintaining the software.

Deploy

After testing, the software is ready for deployment. Organizations often deploy software in phases, releasing it to specific customers or stakeholders for beta testing before releasing it to the general public. This “test run” of the new software ensures the new product will hold up in a real-world environment.

Maintain

Lastly, the team maintains the software, looking for system performance, security, and user experience issues. Then, they use these observations or user reports to release fixes.

Teams often maintain separate build and production environments so they can iteratively improve software without affecting the live version. They keep a copy of the software live in the production environment, while another workable copy stays in a build environment. Updates are made to the build environment and released once a polished version is ready. This way, the software is still available to customers as the team works on improving and maintaining it behind the scenes.

What are SDLC models?

Teams tend to use a few common SDLC models based on their IT structure, team processes, and overall organizational goals. Here are a few examples of frequently used models:

Waterfall

As the name implies, this model is conceptually similar to a waterfall. The team tackles one phase, and once completed, it “flows” down into the next phase sequentially. While this model enables teams to see complete results after each phase and keep to a highly structured schedule, it also makes it challenging to make changes once each stage is completed. So, if an issue comes up later in the project, it takes extra time and costs to remediate it.

Iterative

In this process, the team spends less time in the planning and designing phases and, instead, goes into the implementation phase with a small subset of requirements. Then, they release different versions over time until the software is ready for deployment. While this approach allows teams to adapt to new issues as they go, it also makes it difficult to accurately estimate the time and costs required for the entire project.

Spiral Model

The spiral model is a hybrid of the iterative and waterfall models. In this model, development conducts release cycles following the sequential order of a waterfall process but leveraging a small subset of requirements. This process works best for large and complex projects, as it can become costly when used with smaller projects.

Agile Model

Agile methodology takes an incremental approach to software development. Teams release smaller units in sprints rather than waiting for an entire SDLC phase to be completed before moving on to the next one, as with the waterfall model. Many modern teams use an agile approach, and Aras solutions support this approach.

By leveraging the agile model, teams can better identify and address issues early, making correcting problems without affecting other project areas easier. Many agile teams also collect feedback earlier in the life cycle when they can easily incorporate it without dramatically affecting costs or resources. However, this method is more prone to unexpected scope changes, as it invites more variables early in the process.

V-Shaped (aka “Verification” or “Validation”) Model

This model focuses on executing smaller tests, such as unit and integration tests, throughout the implementation stage. This “early and often” testing mentality enables teams to catch bugs and quality issues early in the cycle. It reduces the number of fixes the developers must make later in the life cycle. Because it combines testing with every stage of development, the v-shaped model is more resource- and time-intensive than other methods.

Big Bang Model

This model simply focuses on releasing software without set requirements or planning. The project goals are understood well enough without a written plan, and code is built ad hoc to create the final product. This informal development model can only work for small teams with vague scopes and deadlines. It is mainly seen in academic environments.

How the SDLC addresses security

As teams build out a software development lifecycle, they must also consider cybersecurity. Many teams choose to take a DevSecOps approach, integrating security into each stage of the SDLC. As part of DevSecOps methodology, teams perform security activities such as code reviews at each stage of development. For instance, a developer might run a static application security testing (SAST) scan on a code unit before they commit it to the central repository. Addressing security concerns early in the SDLC enables teams to fix code vulnerabilities and other security flaws before the issue gets built upon later in the pipeline.

Benefits of the SDLC

When teams use an SDLC to release software, they experience several benefits, including:

• End-to-end visibility of the entire process, documented for any stakeholders to see
• More accurate estimations of required costs, time, and resources
• Overall better products, as this process takes customer feedback, internal expertise, and in-depth functional and quality assurance testing into account

Teams that must release custom software instances, such as customized product lifecycle management (PLM) technology, reap these benefits when they leverage SDLC to release features. This tried-and-true structure for releasing software allows them to build out a custom instance tailored to their users and specific requirements. Unlike software sold as a product to businesses or customers, internal users in an organization, such as engineers, will use the custom PLM solution. In this case, teams must consider the technological features these “internal customers” need to build high-quality physical products. Their requirements and practical use cases become part of the planning and designing phases of the PLM platform’s software development lifecycle.