Evolution of Composition Filters to Event Composition

Various different aspect-oriented (AO) languages are intro- duced in the literature, and naturally are evolved due to the research activities and the experiences gained in applying them to various domains. Achieving modularity, compos- ability and abstractness in the implementation of crosscut- ting concerns are typical requirements that these languages aim to fulfill; and the degree to which they are fulfilled dif- fers per language. Therefore, we always face two questions: what are the limitations of current AO languages from the perspective of these requirements, and what kinds of changes and/or new language mechanisms are necessary to address the limitations. This paper elaborates on the limitations of the current AO languages by means of runtime enforce- ment as an example domain. Via a new computation model termed as Event Composition Model, which is a successor of the Composition Filters Model, we outline the new language mechanisms that are necessary to overcome the limitations. This paper introduces the EventReactor language as an im- plementation of Event Composition Model, and by means of an example runtime enforcement technique, it illustrates the suitability of Event Composition Model to achieve bet- ter modularity, composability and abstractness in the im- plementation of concerns.