An Introduction to UML: The Component Model
This paper describes how to model software and hardware components in the UML. The component model illustrates the software components that will be used to build the system. These may be built up from the class model and written from scratch for the new system, or may be brought in from other projects and third party vendors. Components are high level aggregations of smaller software pieces, and provide a 'black box' building block approach to software construction.