Building complex component-based software architectures can lead to subtle assemblage errors. In this paper, we introduce a type- system-based approach to avoid message handling errors when assembling component-based communication systems. Such errors are not captured by classical type systems of host programming lan- guages such as Java or ML. Our approach relies on the definition of a small process calculus that captures the operational essence of our target component-based framework for communication sys- tems, and on the definition of a novel type system that combines row types with process types.