The（）is a general description of  the architecture of a workflow management system  used  by  the WFMC，  in which  the main  components  and  the  associated  interfaces  are summarized.The workflow enactment service is the heart of a workflow system which consists of several（）.In a workflow system， a process is specified using the process definition tool.Usually， processes  are  defined  in terms of  a（）， which consists  of（）indicated using a circle， and（）shown as a rectangle.These two components can be linked by means of a directed arc.