Policy-based Workflow Management System

Having studied the specification of workflow management system proposed by Workflow Management Coalition (WfMC), the author considers that there are two serious weaknesses in traditional workflow system: 1.build-time is strongly coupled with run-time; 2.system is static at run-time. A lot of research work tried to relieve the negative influence of the weaknesses, however, the system structure has to be reconstructed to get rid of these weaknessesIn this thesis, a policy management paradigm is introduced into the workflow system. Policy is a style of declaration and formulation. It is applied in automation field to conduct the behaviors of entities. Policy can be divided into abstract type and concrete type. During the process, Policy Server translates an abstract policy to a concrete one which can be executed by the Server. The application of policy technology can overcome the weaknessesThe author combines policy and basic workflow process definition meta-model which is defined by WfMC, develops a policy based workflow process definition meta-model. This meta-model can be used in the design and the implementation of the system.Then the author analyzes some main-stream policy languages and has found that those policy languages are specialized for network management and not suitable for workflow system. Base don this consideration, the author designs a new policy language, called Workflow Policy Language, for workflow system. The new policy rule provides a sound base for new workflow system. The archutecture of the new system is presented in this thesis. And the Java platform has been used in the system implementation.To guarantee the efficiency of the system and reduce the possibility of exceptions, the workflow process must be modeled and analyzed carefully before its execution. In the new system, a new workflow process routing model, which is named as election routing, is studied by the author. This new routing model leads to a special issue named as "Minority Issue". To adapt to the new model and solve the new problembrings about by"Minority Issue", a new modeling system is developed based on Petri net system in this thesis, which is called Variant Petri Net System. Building a sound VPNS model for workflow process will improve the efficiency during the system run-time.The author brings forward a creative concept of policy based workflow management system. The result shows that the work described in this thesis is very promising in the development of new type workflow system.