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.

Research on Modeling and Schedule of the Workflow Multiple Instances Activity;

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

According to the structure of multi-hierarchy case,the subspace of multi-hierarchy case was presented and a subspace method was proposed for multi-hierarchy case retrieval,and an algorithm of multi-hierarchy case matching was presented based on grey relational analysis.

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.