A novel approach of workflow instance migration using virtual execution rule

In the dynamic workflow system, solving running workflow instance is an important and challenging research. A new approach of workflow instance migration is proposed based on the formal workflow model and definition of workflow instance with execution history. In this paper, a criterion for workflow instance migration was presented, which decides whether a particular workflow instance can be correctly migrated to a new workflow model or not in terms of workflow execution history. According to the criterion, a virtual execution rule was proposed, which satisfies the criterion and gives the sufficient and necessary conditions for workflow instance migration in virtual execution method simulating the routing process of workflow engine. The implementation steps of migration algorithm based on the virtual execution rule was described in detail.