A Brief Tour of Join Point Interfaces

In standard AspectJ, aspects and base code are often in-sufficiently decoupled, as aspects hold pointcuts, which can contain explicit textual references to base code. This hin-ders aspect evolution and reuse, and may hinder reasoning about aspects on the base-code side. In this demo we present join point interfaces as an ex-tension to the aspect-oriented programming language As-pectJ. Opposed to AspectJ, with join point interfaces as-pects and base code communicate only through a shared interface abstraction. Aspects themselves go without point-cuts and only reference the interface. Pointcuts are typically defined on the base-code side, or not at all, as join point interfaces also support pure explicit invocation as known from publish-subscribe systems. As a result, users obtain a language which decouples aspects from base code using a modular type-checking algorithm, and which they can use to adopt aspects gradually as they desire. One major undertaking in the design of join point inter-faces was to make the language as flexible to use as standard AspectJ, while nevertheless providing interfaces supported by strong type checks that can completely avoid type er-rors at composition time. In this demo we will discuss this inherent trade-off, we will present JPIs as an extension to the AspectBench Compiler, and will show how the language eases the maintenance of existing AspectJ applications