PROSE: a study on dynamic AOP

An obvious prerequisite for both fixed and mobile computing is the ability to adapt (i) to different computing environments or (ii) to external changes occurred in their current computing environment. Otherwise the services are forced to be foreseen with everything they may possibly need during their operationallife time. This is neither desirable nor feasible, thereby hinting at the need for dynamic adaptation. Recent developments in service architectures suggest that dynamic adaptations could be implemented with dynamic AOP. This thesis studies the application requirements on run-time AOP support and presents a system that addresses these requirements. The support for weaving is separated from the AOP system, which is treated as an exchangeable module on top of the weaving support. This approach allows to providing low run-time overhead, AOP system flexibility, and secure weaving. An extensive empirical evaluation, a discussion of the trade-offs resulting from using various approaches for the weaving support (JIT-based, debugger-based), and amodularized architecture are presented. In the resulting system, PROSE, aspects are expressed in the same source language as the application (Java), and PROSE allows aspects to be woven, unwoven, or replaced at run-time. Once every node of a (mobile or fixed) network is equipped with PROSE, the next step is to let the environment, represented by nearby computing nodes, to be proactive and adapt the application rather than forcing the application to adapt itself to every possible environment. This leads to a generalization of the container model into a new software architecture, the spontaneous container. A spontaneous container allows to homogeneously extend all applications of a network, even if they spontaneously join or leave the network. This thesis shows how to build a spontaneous container by unifying different technologies into one coherent architecture: (i) dynamic aspectoriented programming, (ii) containers, and (iii) infrastructures for mobile computing. Dynamic aspect-orientation makes a spontaneous container much more flexible than existing commercial containers. Inheriting the container programming model allows a single focus point for modifications for all applications in a network. Basing the overall architecture on dynamic service brokerage and discovery allows a seamless integration with existing infrastructures for both mobile and fixed computing. Following these ideas, this thesis evaluates a spontaneous container prototype that effectively and efficiently transforms applications within a network into a distributed system capable of transactional interaction, access control, and orthogonal persistence.