The idea that stands behind the Software Development Life Cycle (SDLC) models was to lower the cost of software development, while at the same time improving quality and shortening production time. It consists of a detailed plan describing how to develop, maintain and replace specific software. The life cycle defines a methodology for improving the quality of software and the overall development process.
The software development life cycle is also known as the software development process. SDLC involves several distinct stages, including planning, design, building, testing, and deployment. Popular SDLC models include the waterfall model, spiral model, and Agile model.
What are the phases of SDLC?
Planning: The most important parts of software development, requirement gathering or requirement analysis is usually done by the most skilled and experienced software engineers in the organization. At this stage, you need to define your requirements, estimate the costs and required resources. After the requirements are gathered from the client, a scope document is created in which the scope of the project is determined and documented.
Implementation: The software engineers start writing the code according to the client's requirements.
Testing: It’s time to make sure that the application is of the highest quality and that it meets the requirements.
Documentation: Every step in the project is documented for future reference and for the improvement of the software in the development process. The design documentation may include writing the application programming interface (API).
Deployment: The software is deployed after it has been approved for release.
Maintaining: Software maintenance is done for future reference. Software improvement and new requirements (change requests) can take longer than the time needed to create the initial development of the software.
There are some software development models followed by various organizations:
Waterfall Model: This model involves finishing each phase completely before commencing the next one. When each phase is completed successfully, it is reviewed to see if the project is on track and whether it is feasible to continue.
Agile Model: The Agile SDLC model separates the product into cycles and delivers a working product very quickly. This methodology produces a succession of releases. Testing of each release feeds back info that’s incorporated into the next version. According to Robert Half, the drawback of this model is that the heavy emphasis on customer interaction can lead the project in the wrong direction in some cases.
V-Shaped Model: This model focuses on the execution of processes in a sequential manner, similar to the waterfall model but with more importance placed on testing. Testing procedures are written even before the commencement of the writing code. A system plan is generated before starting the development phase.
Incremental Model: This life cycle model involves multiple development cycles. The cycles are divided up into smaller iterations. These iterations can be easily managed and go through a set of phases including requirements, design, implementation, and testing. A working version of the software is produced during the first iteration, so working software is created early in the development process.
Iterative Model: This SDLC model emphasizes repetition. Developers create a version very quickly and for relatively little cost, then they test and improve it through rapid and successive versions. One big disadvantage here is that it can eat up resources fast if left unchecked.
Big Bang Model: This high-risk SDLC model throws most of its resources at the development and works best for small projects. It lacks the thorough requirements definition stage of the other methods.
Spiral Model: The most flexible of the SDLC models, the spiral model is similar to the iterative model in its emphasis on repetition. The spiral model goes through the planning, design, build and test phases over and over, with gradual improvements at each pass.