Abstract: We improve current visual component composition environments by introducing composition patterns as first class objects that can be defined, stored and reused independently of the components. We document both components and composition patterns using an extended sequence diagram notation. For a component, typical usage protocols are specified while a composition pattern specifies how a set of roles interact. From this documentation, we check whether a component can work as described by a composition pattern using finite state automata theory and we generate glue-code for the composition. In this paper we present our approach, explain the checking algorithms and glue code generation and discuss the tool support we developed.