Management of workflow resources to support runtime adaptibility and system evolution

This paper proposes some ideas for the enhancement of the flexibility and adaptability of workflow systems. The flexibility and adaptability problem is discussed from two perspectives, namely design and evolution of workflow software from a system perspective as well as redesign and runtime on-the-fly modification of workflow models from an application perspective. We argue that based on a systematic management of workflow resources including workflow models, software components, persons and roles, as well as data and documents, workflow systems can be engineered from these two perspectives convergently. A new process modeling language, called Higher-Order Object Nets (HOON), is discussed. The intended uses of HOON are not only to directly describe real-world business processes but also to serve as an overall control skeleton of the underlying software components supporting individual business activities. Besides inheriting the basic features of Petri nets, HOON incorporate mechanisms which enhance the structural flexibility of Petri nets through dynamic binding of resources, and support reuse and composition of submodels in an object-oriented way. Concerning systems design and evolution, a process-model-driven framework for developing configurable workflow systems is presented. The framework, which is based on HOON and the distributed object computing technology CORBA, can serve as the system core for a variety of work-flow systems and remain stable in the process of system evolution in which software components and process models are all subject to modification and substitution.