In component-based system, connectors are used to compose components. Connectors should have a semantics that makes them simple to construct and use. At the same time, their semantics should be rich enough to endow them with desirable properties such as genericity, compositionality and reusability. For connector construction, compositionality would be particularly useful, since it would facilitate systematic construction. This paper we describe a hierarchical approach to component and connector definition and construction that allows components and connectors to be defined and constructed from sub-components and connectors. These composite elements are indeed generic, compositional and reusable.