Flow Model, Based On The Database Representation

There are hundred commercial workflow products in the market nowadays, howerver the weakness or limitation of these system still exists. For example, when they are used in the large scale environment, they can hardly support large amount of users and processes running concurrently, or they lack of mechanism for backup and efficient recovery, availability, scalability, robustness. On the other hand, database, which is an important relevant technology, has already solved this kind of problem. Therefore, the idea of using database representation to design and realize workflow came into mind."Based on database representation" means that database is the centric and fundamental part of the workflow management system, where not only process definition, process instances are stored in the database, but the workflow engine can be developed directly by using the procedure SQL language as well.The architecture of the workflow model based on database representation is very simple, easy to implemente, expressive enough to define complex processes, and has the ability of dynamic process reconfiguration, flexible task assignment. Moreover this model inherit the functionalities and properties of large scale database management systems : the support of large amount of concurrent users and processes, backup and recovery function, failure detection, security mechanism, system robustness, transaction model etc. In a word, this model can simplify the design of workflow server, while improve the performance of it.