Web-based workflow framework with CORBA

Workflow is an important class of applications in the daily business. A number of web-based workflow systems have been developed recently as a natural extension to traditional workflow systems to exploit the growing popularity of the Internet. However, most of them are designed based on the specific application at hand. In this paper, we distill out the fundamental elements of a workflow system into a general workflow framework. The framework provides appropriate application programming interfaces for programmers to fill in the application specific requirements of a workflow system at hand. This is realized through two object-wrappers: the Task interface and the Resource interface, which support the specification of the tasks involved in the workflow schedule and the resources accessed respectively. A major characteristic of the framework is that the particular workflow schedule under execution is fluid, in the sense that the tasks involved as well as their precedence relationships can be modified dynamically. Consistency constraints will be examined in this paper which determine when such modifications are allowed. To maximize flexibility, we adhere our design to the CORBA architecture, which has been becoming highly popular in recent years, thus allowing tasks and resources of different types to interoperate in our framework. We demonstrate the feasibility of our framework with a small prototype that allows tasks in a workflow system to be scheduled and executed.