As such, a component may itself conform to and provide the realization of a set of interfaces, which represent services implemented by the elements resident in the component. These services define behavior offered by instances of the component as a whole to other client component instances. In the UML, a component is a classifier, and so may realize interfaces, have executable behavior and state. These things are also true of subsystems. However, Packages are distinguished by the fact that they can contain model elements, so we are left questioning how subsystems and components differ.
Systems can contain subsystems, which can contain components, which can contain objects.
While Figure 1 reveals where components typically reside in the taxonomy of architectural things, it doesn t tell us what they are and how they are used. Can be integrated into a system quickly and smoothly. However, this definition applies to objects of all sizes. They should also fit together into collaborations to realize larger scale behavior and ought to be easily integratable. First, I want to say a few words about component behavior, interfaces and state.