A Reflective Approach to Process Model Customization, Enactment and Evolution

Software processes are enacted instances of process models. Process models are themselves instances of process meta-models that provide the various abstractions in terms of which process models can be described. This paper introduces a unified framework for software process modeling, enactment and evolution. The approach supports the customization/evolution of a process model and of its underlying meta-model. The process model and its meta-model are both described as specializations of kernel object classes using an object-oriented definition toolkit. Classes at one level become object instances at the upper level. The customization/evolution of models and meta-models is supported in a uniform way by creation/modification of kernel objects and by specialization of their classes. The overall approach is illustrated through a number of simple examples. Our definition toolkit has been written in Standard ML. This choice allows a precise semantics to be assigned to the various constructs using denotational semantics description techniques; at the same time executable prototypes of process-driven environments are produced from such descriptions