Through extension of the traditional workflow engine,scheduling policy of data flows in workflow of activity instances is presented,and the key scheduling algorithms are realized according to the validation rule of data consistency,such as data preparation and data.

The formalized description of process instances and activity instances leads to very clear structure of the workflow engine, has easy cooperation of the heterogeneous workflow engines and guides the realization of the workflow engine function.

According to the model of workflow based on Markov chain the relation of interoperability between the process object in logical realm and activity instance in active realm was di.

In order to eliminate the covert channels, the polyinstantiation and the cover story are used in the new data model.

Semantic ambiguity and the problem of increasing tuples brought up by update operation,which exist in current polyinstantiation based data models,complicate much the implementation of system and the operation of users.

It introduces a new modeling element, cooperative activity node, and new modeling mechanisms such as multi-instantiation, dynamic creating and revising of the model.