Abstract: The study describes an application composition and execution environment implemented as a workflow system that enables sets of inter-related tasks to be carried out and supervised in a flexible manner. Concerning the serious deficiency of flexibility in the current workflow systems, we describe how our workflow system meets the requirements of interoperability, scalability, flexibility, dependability and adaptability. With an additional route engine, the execution path will be adjusted dynamically according to the execution conditions so as to improve the flexibility and dependability of the system. A dynamic register mechanism of domain engines is introduced to improve the scalability and adaptability of the system. Finally we put emphasis on describing process executing sequence of our system. The system is general purpose and open: It has been designed and implemented as a set of CORBA services. The system serves as an example of the use of middleware technologies to provide a fault-tolerant execution environment for long running distributed applications. The system also provides a mechanism for communication of distributed components in order to support inter-organizational WFMS.