Re ection on a Legacy Transaction Processing Monitor

In this paper we describe our experience applying the concepts of re ection to a legacy transaction processing (TP) monitor in order to support the implementation of extended transaction models. In the past ten years, numerous extended transaction models have been proposed to address challenges posed by new advanced applications. Few practical implementations of these extended transaction models exist, and none are being used in a commercial TP monitor. We believe the reason for this state of a airs is that the interface and functionality of commercial TP monitors is \locked in" to a xed transaction model. We have developed the Re ective Transaction Framework as a practical method to implement extended transaction models on a commercial TP monitor. The design of our framework is based on the principles of computational re ection, and in particular open implementation. The implementation of our framework introduces transaction adapters, which are re ective software modules that provide a meta interface to the underlying TP monitor, allowing application developers the exibility to adjust both the application programming interface and system functionality. Unlike classic re ective systems, the Re ective Transaction Framework applies re ection to a legacy TP monitor written in a non-re ective programming language. This paper focuses on the ability of the Re ective Transaction Framework to perform re ective computation and on the extent to which the legacy TP monitor supports this computation.