Software Development LifeCycle (SDLC)

What is SDLC?

The Software Development Life Cycle (SDLC) is a structured process that enables the production of high-quality, low-cost software, in the shortest possible production time. The SDLC defines and outlines a detailed plan with stages, or phases, that each encompass their own process and deliverables. 

How does the SDLC work?

What are the SDLC models/methodologies?
Waterfall
Waterfall represents the oldest, simplest, and most structured methodology. Each phase depends on the outcome of the previous phase, and all phases run sequentially. This model provides discipline and gives a tangible output at the end of each phase. However, this model doesn’t work well when flexibility is a requirement. There is little room for change once a phase is deemed complete, as changes can affect the cost, delivery time, and quality of the software.

Agile

The agile methodology produces ongoing release cycles, each featuring small, incremental changes from the previous release. At each iteration, the product is tested. The agile model helps teams identify and address small issues in projects before they evolve into more significant problems. Teams can also engage business stakeholders and get their feedback throughout the development process.

Iterative

In the iterative process, each development cycle produces an incomplete but deployable version of the software. The first iteration implements a small set of the software requirements, and each subsequent version adds more requirements. The last iteration contains the complete requirement set.

Spiral
The spiral model carries out development in loops. Each iteration also known as a phase has four stages. A software plan repeatedly passes through these phases in repetitions called Spirals.

During  the last stage, Risk Analysis comprises classifying, measuring and observing the technical feasibility and business risks, such as schedule impact and cost escalations. After examining the build, at the end of the first repetition, the customer assesses the software and gives feedback.

Based on the client evaluation, the software development method enters the next iteration and consequently follows the direct approach to complete the feedback recommended by the customer. The process of iterations along the spiral lasts throughout the lifespan of the software.

 

V-Shaped
In the V-shaped model, verification phases and validation phases are run in parallel. Each verification phase is associated with a validation phase, and the model is run in a V-shape, where each phase of development has an associated phase of testing.