We now turn our attention to the design of the Reflective Transaction Framework. To open up the functionality of a legacy TP monitor we introduce transaction adapters, which are add-on reflective software modules that provide a meta interface to the underlying TP monitor. In addition, to open up the application interface to the TP monitor we introduce a separation of programming interfaces.
Although the Reflective Transaction Framework applies reflection in a non traditional sense, to a legacy TP monitor written in a non-reflective programming language, it nevertheless incorporates many of the ideas from the traditional notion of computational reflection. An important difference is that reflecting on a legacy system implies a strict separation between base and meta objects, as opposed to the metacircular interpreters from traditional computational reflection. In our framework this base/meta object separation is implemented by introducing transaction adapters. Adapters do not have a full model of the entire monitor, but only a partial model of selected aspects of the underlying TP Monitor. However, reflection is still very much present and, as we will demonstrate, it does enable transaction adapters to open up the legacy TP monitor functionality and extend it to implement extended transaction models.