Designing Reusable Patterns of Cross-Cutting Behaviour with Composition Patterns

1. INTRODUCTION The current limitations in the decomposition capabilities of object-oriented software force the tangling of cross-cutting behaviour with all other elements that it affects. This has a negative impact across the development lifecycle, from comprehensibility, traceability, evolvability and reusability points of view. This problem has been addressed within the programming phase by the subject-oriented programming [4, 10] and the aspect-oriented programming [7] paradigms. Within these paradigms, cross-cutting behaviour may be cleanly separated from functional code. However, to gain the benefits of software engineering across the development lifecycle, it is important to be able to provide similar separation capabilities at earlier stages in the lifecycle. Currently, this problem has not been effectively addressed for the design phase. Within the subject-oriented design paradigm [2,3], composition patterns are defined to capture the design of patterns of cross-cutting behaviour. These patterns may then be composed with any design model requiring that behaviour. The approach is therefore easily mapped to any programming model that supports similar separation of concerns, as illustrated in this paper.