A Sequence of Patterns for Reusable Aspect Libraries with Easy Configuration

Using well-known AspectJ idioms has been shown to increase the reusability of aspect libraries. Availability of such reusable libraries is an important motivating factor to drive the further adoption of AspectJ in industry and aspect-oriented-programming in general. Existing work, however, mostly presents the existing AspectJ idioms as relatively independent solutions. As experience grows in using these idioms, it is possible to increasingly combine related idioms to form patterns and subsequently, pattern languages. A pattern language provides a structured process on how to apply a family of related patterns and idioms that cover a particular domain or discipline. This paper presents a first step towards a pattern language for building reusable aspect libraries in the form of a sequence of aspect-oriented patterns that each combine a set of idioms to achieve (i) a configurable core design of the aspect library, (ii) library-controlled mediation of the interactions between the different aspects in the library and (iii) flexible configuration by providing multiple alternative modes for binding the aspect library to an application. An initial evaluation of the pattern sequence in the context of a pricing library shows improved reusability and ease-of-configuration in comparison to an existing idiom-based implementation of the pricing library.