Monitoring, security, and dynamic configuration with the dynamic TAO reflective ORB

Conventional middleware systems fail to address important issues related to dynamism. Modern computer systems have to deal not only with heterogeneity in the underlying hardware and software platforms but also with highly dynamic environments. Mobile and distributed applications are greatly affected by dynamic changes of the environment characteristics such as security constraints and resource availability. Existing middleware is not prepared to react to these changes. In many cases, application developers know when adaptive changes in communication and security strategies would improve system performance. But often, they are not able to benefit from it because the middleware lacks the mechanisms to support monitoring (to detect when adaptation should take place) and on-the-fly reconfiguration. dynamicTAO is a CORBA-compliant reflective ORB that supports dynamic configuration. It maintains an explicit representation of its own internal structure and uses it to carry out runtime customization safely. After describing dynamicTAO’s design and implementation, we discuss our experience on the development of two systems benefiting from the reflective nature of our ORB: a flexible monitoring system for distributed objects and a mechanism for enforcing access control based on dynamic security policies.