Using AOP to bring a project back in shape: the ourgrid case

the design and development of distributed software is a complex task. this was not different in ourgrid, a project whose objective was to develop a free-to-join grid. after two years of development, it was necessary to redesign ourgrid in order to cope with the integration problems that emerged. this paper reports our experience in using aspect-oriented programming (aop) in the process of redesigning the ourgrid middleware. the essential direction of our approach was to get the project (and the software) back in shape. we discuss how the lack of separation of concerns created difficulties in the project design and development and how aop has been introduced to overcome these problems. in particular, we present the event-based pattern designed to better isolate the middleware concerns and the threads. besides, we also present the aspects designed for managing the threads and for aiding the testing of multithreaded code. we also highlight the lessons learned in the process of regaining control of the software.