OOAD

Object-oriented analysis and design (OOAD) is a software engineering approach that uses object-oriented concepts to analyze requirements and design software systems. It separates the work into analysis, which models the problem domain in terms of objects, their attributes, and responsibilities, and design, which specifies the software solution in terms of classes, objects, and their interactions. The aim is to produce software that is modular, extensible, and closely aligned with real-world entities while supporting reuse and maintainability.

OOAD drew popular attention in the 1990s through the work of Grady Booch, Ivar Jacobson, and James Rumbaugh, whose methods and notations later formed the Unified Modeling Language (UML). Modeling artifacts commonly used in OOAD include use-case models to capture requirements, domain models, class diagrams, sequence diagrams, state machines, and activity diagrams. The core concepts are objects and classes, encapsulation, abstraction, inheritance, polymorphism, and messaging. Good OOAD practice emphasizes proper coupling and cohesion to keep components interchangeable and maintainable.

Practically, OOAD proceeds in an iterative fashion, typically beginning with analysis to identify key objects and their responsibilities, followed by design to define object collaborations and interfaces. It is closely associated with object-oriented programming languages such as Java, C++, C#, and Python, which map naturally to OO concepts. Benefits of OOAD include clearer software structure, improved reusability, and easier evolution of systems; drawbacks include the potential for over-modeling, steeper learning curves, and complexity in projects with rapidly changing requirements.

While OOAD remains a foundational approach, modern development often blends object-oriented techniques with other paradigms and lightweight modeling, depending on project needs and team expertise.