The Software Development Lifecycle (SDLC) allows developers to pick up errors in software creation before they create a stumbling block at the next stage. The process has several distinct stages… planning, analysis, design, building, testing, deployment, and maintenance. By moving through each stage, devs can flag errors and help lay out a plan for getting each stage right first time.
There are several Software Development Lifecycle Models to consider when planning your next project. Each has distinct variations but do share a common purpose. They all aim to help software engineering teams deliver high-quality software as quickly and cost-effectively as possible.
Here are 6 of the most common SDLC models.
The Agile Model has become the industry standard since it first arrived on the scene in 2001. This approach produces ongoing release cycles, with each release showing small incremental changes from the one before it. With each change, the product is tested and so the Agile model can identify and resolve small issues before they grow into more significant ones. Fast failure is a good thing and encourages stakeholders to give feedback throughout the development process.
As part of this methodology, many teams choose to also apply an Agile framework known as Scrum. Daily Scrum meetings are held to help the team collaborate and monitor the progress of the project. These Scrum teams work in Sprints, which are short, time-boxed periods in which teams work to complete a set amount of work.
Want to know more about Agile? Read our tips on how to run your Agile project here.
The Lean model is inspired by “lean” manufacturing practices and principles. There are 7 Lean principles. These are
- To eliminate waste
- To amplify learning
- To decide as late as possible
- To deliver as fast as possible
- To empower the team
- To build in integrity
- To see the whole
The Lean process has no element of multitasking. Teams using this methodology work on only what must be worked on at the time. Project teams also focus on cutting waste and working efficiently and resourcefully at each stage. For example, unnecessary meetings won’t be held, and needless documentation won’t be required.
The Agile model is a Lean method for the SDLC, but with some distinctions. Regarding customer satisfaction, Agile prioritises this from the outset. Agile creates a process where teams can respond quickly to customer feedback. In contrast, Lean emphasises the elimination of waste to create more value and satisfaction for customers.
Waterfall is widely believed to be the oldest of the structured SDLC methodologies, although some theorists argue that it was never intended to be a process model for real projects.
It has a very simple roadmap; finish one phase, then move to the next. Using Waterfall there is no going back. Each stage uses information from the one before it and each has its own project plan.
Although Waterfall is straightforward, it is also rigid. The lack of room for revisions or adjustments once a stage is completed means that delays can disrupt the entire project. Problems can’t be fixed until the project reaches the maintenance stage.
Even more structured than this is an offshoot of Waterfall called the Verification and Validation Model – or V-shaped model. This model is characterised by a corresponding testing phase for each development stage. Just as in its parent model, each stage only begins after the close of the previous one.
These models are considered useful but are mainly only used for those projects with no unknowns. They are very rarely used if the project is long and ongoing, or if it requires an element of flexibility.
The Iterative model relies upon repetition. The team does not start with fully known requirements. Instead, they begin with a set of software requirements that are tested, evaluated, and evolved to establish a further set of requirements. Using the Iterative model, a new version of the software is reproduced at each phase or iteration. This process is repeated until the system is ready.
Although laborious, one advantage of this methodology is that it produces a working model of the project early in the process, making it less expensive to implement changes. It is disadvantageous in one respect, however. Such a repetitive process can eat up resources and budget very quickly.
Typically used for large projects, Spiral takes a spin off the Iterative model. It is one of the more flexible SDLC models.
Using Spiral, the project goes through 4 phases;
- Risk analysis
The project repeats these over and over, going through multiple rounds of refinement until the project is completed.
Using Spiral, teams can build a highly customised product and respond to user feedback early on. Another benefit is risk management. Each iteration begins by foreseeing potential risks and attempts to avoid or mitigate these.
DevOps was born from 2 established trends and is a relative newcomer to the SDLC conversation.
In a DevOps model, Developers and Operations teams work together closely to improve innovation and the deployment of improved quality and reliable software products and functionalities. A DevOps team creates small and frequent updates through its values of discipline, continuous feedback, process improvements, and the automation of manual development processes.
DevOps has been described as a combination of cultural philosophies, practices, and tools that can increase an organisation’s ability to deliver applications and services at speed. It delivers an evolving product and offers improvements quicker than companies using traditional software development and infrastructure processes. DevOps is not only a practical application for planning and completing tasks. It is a philosophy that requires a non-traditional mindset from the organisation if success is to be reached.
Are you part of a software team? What are your experiences of these models? Do you have a favourite? Let us know in the comments below.
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