What is a software development life cycle (SDLC)?

Purpose of using SDLC

The main goal of using a defined SDLC is to ensure systematic, predictable, controllable and high quality in the software development process. The structured approach helps improve planning, resource management, team communication, risk identification and management, and delivery of a product that meets stakeholder expectations on time and within budget. SDLC also makes it easier to maintain and develop software in the future.

Typical phases (stages) of the SDLC

While there are many different SDLC models (e.g., cascading, iterative, spiral, agile), most include similar key phases, even if they are implemented in a different order or in an iterative fashion:

• Planning (Planning): Defining project scope, business objectives, feasibility study, preliminary estimation of resources, costs and schedule.
• Requirements Analysis: Gathering, analyzing, documenting and validating functional and non-functional requirements for the system. Understanding user and stakeholder needs.
• Design (Design): Creating system architecture, user interface design (UI/UX), database structure design, and detailed design of application components and modules.
• Implementation/Coding: Writing of application source code by developers according to design and coding standards.
• Testing (Testing): Verification and validation of software to detect errors and ensure compliance with requirements. Includes various levels of testing (unit, integration, system, acceptance).
• Deployment (Deployment): Installing and configuring the software on a production environment, making it available to end users.
• Maintenance: Ongoing user support, fixing bugs found after implementation, making minor improvements, and adapting the software to a changing environment.
• Withdrawal (Retirement): The final phase in which software is retired, often replaced by a newer system.

SDLC models

As mentioned, there are a number of SDLC models, differing in their approach to implementing the various phases:

• Cascade model (Waterfall): A sequential model in which each phase must be completed before the next phase begins. Not very flexible to change.
• Iterative and incremental model: development takes place in cycles (iterations), in each a working piece (increment) of functionality is delivered. Allows for earlier feedback.
• Spiral model: Combines an iterative approach with risk management, each iteration includes planning, risk analysis, implementation and evaluation.
• Agile (Agile) models: E.g. Scrum, Kanban, XP. Emphasize iteration, collaboration with the customer, rapid delivery of working software and adaptation to change. SDLC phases are often intertwined in short cycles (sprints).

The importance of choosing the right model

Choosing the right SDLC model depends on a number of factors, such as the size and complexity of the project, stability of requirements, availability of resources, organizational culture and team preferences. Matching the model to the project context is critical to its success. Modern software development often relies on flexible, agile SDLC models.