Software development life cycle

Introduction

The Software development life cycle (SDLC) is a framework that defines the tasks performed at each step in the software development process. SDLC is a structure followed by a development team within the software organization. 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.

History

The concept of the software development life cycle has been around for several decades, with the first models introduced in the 1960s. The Waterfall model, one of the earliest, is a linear approach to software development where progress flows downwards through several phases, from requirements analysis to design, implementation, verification, and maintenance.

Models of SDLC

There are several models of the software development life cycle, each with its unique approach and sequence of tasks. These models are also known as Software Development Process Models. Each process model follows a particular life cycle to ensure success in the process of software development.

Waterfall Model

The Waterfall model is the earliest SDLC approach that was used for software development. The waterfall Model illustrates the software development process in a linear sequential flow. This means that any phase in the development process begins only if the previous phase is complete.

V-Model

The V-Model is an SDLC model where the execution of processes happens in a sequential manner in a V-shape. It is also known as Verification and Validation model. The V-Model is an extension of the waterfall model and is based on the association of a testing phase for each corresponding development stage.

Incremental Model

The Incremental model is a method of software development where the model is designed, implemented and tested incrementally (a little more is added each time) until the product is finished. It involves both development and maintenance. The product is defined as finished when it satisfies all of its requirements.

Spiral Model

The Spiral model combines the idea of iterative development with the systematic, controlled aspects of the waterfall model. This Spiral model is a combination of iterative development process model and sequential linear development model i.e. the waterfall model with a very high emphasis on risk analysis.

Agile Model

The Agile model is a recent approach to software development and introduces a concept of iterative and incremental development. The software is developed in incremental, rapid cycles, which results in small incremental releases with each release building on previous functionality. Each release is thoroughly tested to ensure software quality is maintained.

Phases of SDLC

The software development life cycle is composed of several phases, each with its unique set of tasks and activities.

Requirement Gathering and Analysis

The first phase of the SDLC involves gathering and analyzing the software requirements. This phase is conducted by the senior members of the team with inputs from all the stakeholders and domain experts in the industry. This information is then used to plan the basic project approach.

Design

In this phase, the software's overall structure and its nuances are defined. System Design helps in specifying hardware and system requirements and also helps in defining the overall system architecture.

Implementation

With inputs from the system design, the system is first developed in small programs called units, which are integrated into the next phase. Each unit is developed and tested for its functionality, which is referred to as Unit Testing.

Integration and Testing

All the units developed in the implementation phase are integrated into a system after testing of each unit. Post integration the entire system is tested for any faults and failures.

Deployment

Once the functional and non-functional testing is done, the product is deployed in the customer environment or released into the market.

Maintenance

There are some issues that come up in the client environment. To fix those issues, patches are released. Also to enhance the product, some better versions are released. Maintenance is done to deliver these changes in the customer environment.

Conclusion

The software development life cycle is a critical framework in software engineering, guiding developers through the various stages of software development. By understanding and applying the principles of SDLC, software developers can ensure that they deliver high-quality software that meets the needs of their clients and end-users.