The Research Of Workflow Dynamic Modification Supporting Exception Handling

The workflow technology is a crucial technology to realize modeling of business process, analyzing of emulations process management and aggregation and ultimately to achieve the goal of automation of business process. More and more enterprises adapt WFMS as a platform to support their business process.The research of workflow is animated. People probe the technology in many aspects, such as workflow model, architecture, transaction, compatibility, exception, safety, language, verification of soundness, management of resources, the process of developing and so on. They also develop meta-model systems to support and check up their theories. There are also many workflow products commercially available in market.Thorough there are rapid progress in workflow research, the theoretical basis of workflow is far from enough. The existing Workflow Management Systems are not comparable with Database Management Systems in functions reliability and soundness. Many factors restrain the development of workflow, which now could not satisfy the utilitarian standard and therefore could not be put to use on a large scale. The factors are various, for example, the foundational model is unsound, the exception handlingstrategy is not integrated and the security of the system is not conformed.Due to the continually accelerating pace of technological advancements, changing requirements and regulations, and introduction of new methods, business process models are being constantly reviewed, improved and adapted to the changing environment. When workflow model changes, some of the workflow instances may still be running. Normally, there are three methods: 1) all current instances are allowed to complete according to the old process model, but new instances are planned to follow new model. New instances may be put on hold, until all current instances have completed. 2) Active workflow instances may be aborted when process model is changed, all instances follow the new model all over again; This approach may incur losses to the organization. In some cases, the losses may be unacceptable. 3) We can bring the instances in compliance with the new specification by undoing or compensating some of the completed tasks. Many dynamic modification algorithms take the third way.Workflow exception handling is a pivot issue which ensure a more reliable process when process execution is wrong. It is necessary to combine the transaction feature of workflow process, Because workflow process has the feature of transaction and it's execution control structure is familiar with advanced transaction model. Researchers present the concept of transaction workflows and advanced workflow model. We will adapt the concept of execution property of tasks to realize more reliable dynamic modification of workflows.One of the major factors restraining the wider applicability and acceptability of workflows is that workflow technology to date does not provide sufficient support for modification of ongoing workflows. The existing modification methodologies have provided comprehensive frameworks to support Dynamic Workflows, but few has paied attention to the exception handling of the Modification process. Exception duringthe modification process would leave the workflow in an inconsistent state or even bring undesirable results in some cases. In this paper, we do the following work:1) giving the definition of task execution property;2) defining a new workflow model, including process execution model3) present a solution for implementing more reliable dynamic modification by adding exception handling in this process.