This paper proposes an Adaptive CORBA Template (ACT), which enables run-time improvements to CORBA applications in response to unanticipated changes in either their functional requirements or their execution environments. ACT enhances CORBA applications by transparently weaving adaptive code into their object request brokers (ORBs) at run time. The woven code intercepts and adapts the requests, replies, and exceptions that pass through the ORBs. Specifically, ACT can be used to develop an object-oriented framework in any language that supports dynamic loading of code and can be applied to any CORBA ORB that supports portable interceptors. Moreover, ACT can be used to support interoperation among otherwise incompatible adaptive CORBA frameworks. To evaluate the performance and functionality of ACT, we implemented a prototype in Java. Our experimental results show that the overhead introduced by the ACT infrastructure is negligible, while the adaptations offered are highly flexible.
