12.1 Program Development Life Cycle

The program development life cycle (PDLC), also known as the software development life cycle (SDLC), is a structured process used to create high-quality software systematically. It outlines the various stages involved in developing a software application, from initial concept to deployment and maintenance. A well-defined PDLC helps ensure that software is developed efficiently, meets user requirements, and is reliable.

Purpose of a Development Life Cycle

The primary purposes of using a PDLC are:

• Improved Software Quality: A structured approach reduces errors and inconsistencies.
• Reduced Development Costs: Early identification of problems minimizes costly rework later on.
• Enhanced Project Management: Provides a clear roadmap, facilitating planning, tracking, and control.
• Better Communication: Facilitates communication and collaboration among stakeholders (developers, clients, testers, etc.).
• Risk Mitigation: Identifies and addresses potential risks early in the process.
• Documentation: Encourages thorough documentation, which is crucial for maintenance and future development.

Typical Stages in a PDLC

While specific models vary, most PDLCs include the following stages:

Stage	Description	Typical Activities	Deliverables
Requirements Gathering	Understanding and documenting what the software should do.	Gathering user needs, conducting feasibility studies, creating use cases, defining functional and non-functional requirements.	Requirements Specification Document
Design	Planning the software's architecture and components.	Creating system architecture diagrams, designing database schemas, defining user interfaces, specifying algorithms.	Design Document
Implementation (Coding)	Writing the actual code based on the design.	Coding the software, unit testing individual components.	Source Code
Testing	Verifying that the software meets the requirements and is free of defects.	Unit testing, integration testing, system testing, user acceptance testing (UAT), bug reporting.	Test Cases, Test Reports, Bug Reports
Deployment	Releasing the software to the users.	Installing the software on servers, configuring the environment, migrating data.	Deployed Software
Maintenance	Addressing bugs, adding new features, and adapting the software to changing requirements.	Bug fixing, performance optimization, feature enhancements, security updates.	Updated Software, Maintenance Logs

Different PDLC models exist, each with its own approach to these stages. Common models include:

• Waterfall Model: A linear, sequential approach.
• Iterative Model: Develops the software in increments, with each increment building upon the previous one.
• Agile Model: An iterative and incremental approach that emphasizes flexibility and customer collaboration. (e.g., Scrum, Kanban)

The choice of PDLC model depends on factors such as the complexity of the project, the level of risk involved, and the client's requirements.