| Aspect-Oriented software development is a methodology proposed to improve separation of concerns and modularization of crosscutting concerns. This methodol-ogy contains series of complement methods from system requirement analysis, design, implementation and testing. Aspect-Oriented programming as the concrete imple-mentation techniques contain new language constructs to support the modularization of crosscutting code. The semantics of these new language constructs are complicate and subtle. The formal studies of the semantics of aspect oriented languages can not only clarify the imprecision of the informal description, but also provide a rigorous theoretical foundation for the development of reasoning, comprehension and analysis techniques.A dynamic operational semantics and a static weaving semantics have been given for a simple aspect oriented functional languages. The consistency has been proved to show the correctness of the weaving algorithm. Though the considered language is very simple and with only simplified aspect constructs, but it provides the csscn-tial techniques for understanding and characterizing the aspect mechanisms. Aspect oriented languages based on imperative languages and object oriented languages arc more complicated to describe. A novel use of the effect systems can not only avoid the liberties of the semantic rules for describe the new language constructs, but also provide a flexible and extensible semantic description method. Program execution effects, runtime states and program execution histories are used to make quantified assertions over program. With such expressive quantification mechanisms, semantics of control flow based pointcuts and dataflow based pointcuts arc given.Higher order chemical computation model can be used to define a general and extensible semantic description framework. The semantics of a simple imperative language has been given within the higher order chemical language. Based on this interpretation, new molecules modeling objects and new reaction rules modeling ob-jects interactions arc defined to give the semantics of an imperative object oriented language. Generally, when new language constructs and control mechanisms arc to be introduced, existed chemical semantic framework can be reused and only new reaction rules arc needed to model these new features.Aspect oriented can be used in other computing environments, like distributed computing, service oriented computing and coordinate computing. Some reprcscn- tative works in these fields are reviewed, with some problems presented and new research directions discussed. |
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