Nowadays, large-scale software systems consist of multiple applications, which interact with each other to fulfill desired system-level requirements. It is usually required to coordinate the interactions of the
constituent applications to ensure that the system-level requirements are
fulfilled. In this paper, we outline a set of requirements that must be
fulfilled to facilitate the modular composition of multiple applications.
We introduce the concept of architectural event modules, which are
abstractions to represent constituent applications and their coordination
logic in a modular and uniform way. We explain the implementation of
this concept in the EventReactor language, and define their formal semantics in processing events using the UPPAAL toolset. We illustrate
the suitability of architectural event modules in achieving modularity and
loose coupling in the composition of multiple applications by means of a
case study in the domain of energy-efficient computing
