The Event-based Aspect-Oriented Programming model (EAOP) makes it possible to define pointcuts in terms of sequences of events emitted by the base program. The current formalization of the model relies on a monolithic entity, the monitor, which observes the execution of the base program and executes the actions associated to the matching pointcut. This model is not intrinsically sequential but its current formalization favors a sequential point of view. In this paper, we present a new formalization of EAOP as finite state processes. This new formalization paves the way to reasoning about aspects in a concurrent setting and to the definition and implementation of concurrent EAOP languages.
