Software Development Life Cycle (SDLC)

The software development life cycle (SDLC) model is a description and diagrammatic model of the software life cycle. Its goal is to identify all the activities undertaken during product development, establish a precedence ordering among the different activities, and divide it into different phases. A more general software life cycle model is depicted as follows:

Why software development life cycle is needed ?

1. It helps a common understanding of activities among software developments and identifies inconsistencies, redundancies, and omissions in the development process.
2. It helps in tailoring a process model for specific projects.
3. The development team must identify a suitable life cycle model and adhere to it to develop software in a systematic and disciplined manner.
4. When a team is developing software, there must be a precise understanding of when to do what. Otherwise, it would lead to chaos and project failure.
5. In a life cycle model, phase entry and exit criteria are defined. Every phase and phase is considered to be complete only when all its exit criteria are satisfied. For example, the exit criteria for the Software Requirement and Specification (SRS) document are to be completed, reviewed, and approved by the customers.
6. Phases also tell the information about the status of the development activities. It helps the project manager to track the progress of the project and realize the development milestones status.
7. Life cycle and project management: When a life cycle model is followed, the project manager can accurately tell about the stage or status of the project; however, without the life cycle, the project manager has to guess the status of the project. This usually leads to a problem known as the 99% complete syndrome.
8. Project deliverables: It is a myth that the only deliverable for a successful project is the working program or product. However, in reality, documentation of all aspects of software development is needed to help in operation and maintenance.
9. Many life cycle models have been proposed as follows:
   • Iterative Waterfall Model
   • V Model
   • Evolutionary Model
   • Prototyping Model
   • Incremental Model
   • Spiral Model
   • Agile Model
   • RAD Model
   • Unified Process Model

Reference

1. Fundamentals of Software Engineering Book & NPTEL Video Lectures by Rajib Mall.

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