As the world became more and more dependent on technology with each passing day, software automatically became an important organ for development. Since software is needed almost everywhere today, its development is a highly intelligent and precise process, involving various steps. It’s pretty evident that technology is accelerating at a rapid pace and humans are becoming further dependent on it for every purpose. And with every new day, software development is becoming more and more crucial since the demand for software is fast rising from every corner imaginable.
Overview and Framework
A software life cycle model (also called process model) is a descriptive and diagrammatic representation of the software life cycle. A life cycle model represents all the activities required to make a software product transit through its life cycle phases. It also captures the order in which these activities are to be undertaken.
Software Development Life Cycle, SDLC for short, is a well-defined, structured sequence of stages in software engineering to develop the intended software product.
SDLC provides a series of steps to be followed to design and develop a software product efficiently. SDLC framework includes the following steps:
Figure 1: SDLC Steps
This is the first step where the user initiates the request for a desired software product. He contacts the service provider and tries to negotiate the terms. He submits his request to the service providing organization in writing.
This step onward the software development team works to carry on the project. The team holds discussions with various stakeholders from problem domain and tries to bring out as much information as possible on their requirements. The requirements are contemplated and segregated into user requirements, system requirements and functional requirements. The requirements are collected using a number of practices as given –
- Studying the existing or obsolete system and software,
- Conducting interviews of users and developers,
- Referring to the database or
- Collecting answers from the questionnaires.
After requirement gathering, the team comes up with a rough plan of software process. At this step the team analyzes if software can be made to fulfill all requirements of the user and if there is any possibility of software being no more useful. It is found out, if the project is financially, practically and technologically feasible for the organization to take up. There are many algorithms available, which help the developers to conclude the feasibility of a software project.
At this step the developers decide a roadmap of their plan and try to bring up the best software model suitable for the project. System analysis includes Understanding of software product limitations, learning system related problems or changes to be done in existing systems beforehand, identifying and addressing the impact of project on organization and personnel etc. The project team analyzes the scope of the project and plans the schedule and resources accordingly.
Next step is to bring down whole knowledge of requirements and analysis on the desk and design the software product. The inputs from users and information gathered in requirement gathering phase are the inputs of this step. The output of this step comes in the form of two designs; logical design and physical design. Engineers produce meta-data and data dictionaries, logical diagrams, data-flow diagrams and in some cases pseudo codes.
This step is also known as programming phase. The implementation of software design starts in terms of writing program code in the suitable programming language and developing error-free executable programs efficiently.
An estimate says that 50% of whole software development process should be tested. Errors may ruin the software from critical level to its own removal. Software testing is done while coding by the developers and thorough testing is conducted by testing experts at various levels of code such as module testing, program testing, product testing, in-house testing and testing the product at user’s end. Early discovery of errors and their remedy is the key to reliable software.
Software may need to be integrated with the libraries, databases and other program(s). This stage of SDLC is involved in the integration of software with outer world entities.
This means installing the software on user machines. At times, software needs post-installation configurations at user end. Software is tested for portability and adaptability and integration related issues are solved during implementation.
Operation and Maintenance
This phase confirms the software operation in terms of more efficiency and less errors. If required, the users are trained on, or aided with the documentation on how to operate the software and how to keep the software operational. The software is maintained timely by updating the code according to the changes taking place in user end environment or technology. This phase may face challenges from hidden bugs and real-world unidentified problems.
As time elapses, the software may decline on the performance front. It may go completely obsolete or may need intense up gradation. Hence a pressing need to eliminate a major portion of the system arises. This phase includes archiving data and required software components, closing down the system, planning disposition activity and terminating system at appropriate end-of-system time.
A Systems Development Life Cycle is a process by which systems analysts, software engineers, programmers, and end-users build information systems and computer applications. It is a project management tool used to plan, execute, and control systems development projects. There are eight basic principles:
- Get the user of the systems involved
- Use a problem solving approach
- Establish phases and activities
- Establish standards for consistent development and documentation
- Justify systems as capital investments
- Don’t be afraid to cancel or revise scope
- Divide and conquer
- Design systems for growth and change
 Walt Scacchi, “Process Models in Software Engineering”, available online at: http://www.ics.uci.edu/~wscacchi/Papers/SE-Encyc/Process-Models-SE-Encyc.pdf
 “Software Development Life Cycle”, available online at: https://www.tutorialspoint.com/software_engineering/software_development_life_cycle.htm
 “Systems Development Life Cycle Principles”, available online at: http://faculty.usfsp.edu/gkearns/Articles/SDLC.HTM