Learning UML 2.0

Chapter 12. Managing and Reusing Your System’s Parts: Component Diagrams

When designing a software system, it’s rare to jump directly from requirements to defining the classes in your system. With all but the most trivial systems, it’s helpful to plan out the high-level pieces of your system to establish the architecture and manage complexity and dependencies among the parts. Components are used to organize a system into manageable, reusable, and swappable pieces of software.

UML component diagrams model the components in your system and as such form part of the development view , as shown in Figure 12-1. The development view describes how your system’s parts are organized into modules and components and is great at helping you manage layers within your system’s architecture.

Figure 12-1. The Development View of your model describes how your system’s parts are organized into modules and components

What Is a Component?

A component is an encapsulated, reusable, and replaceable part of your software. You can think of components as building blocks: you combine them to fit together (possibly building successively larger components) to form your software. Because of this, components can range in size from relatively small, about the size of a class, up to a large subsystem.

Good candidates for components are items that perform a key functionality and will be used frequently throughout your system. ...