A compositional approach to active and passive components Kung-Kiu Lau and Ioannis Ntalamagkas School of Computer Science, The University of Manchester Manchester M13 9PL, UK kung-kiu,i.ntalamagkas@cs.manchester.ac.uk Abstract: Current software component models lack compositionality. Most of them also do not have both active and passive components. In this paper, we show how we can define a compositional approach to active and passive components. We define these components in such a way that their composition can be defined by explicit composition operators. Our approach not only achieves compositionality, but also enables systematic or hierarchical composition.