Origin state is default state of commencement of the
event, when conditions met, activity can go to ready state,
through a trigger mechanism go to perform state, for the
implementing activities or events, it may be suspended or
ended in some abnormal reason. Suspend state can go to
perform state again in workflow engine's management. End
state means end the implementation status of previous step,
go to new ready state. The last step is finish state, this state
can not restart, and it only can begin in the next origin state.
Origin node and activity node select execution's path
through the external conditions. In activity, we need to
define the role of actors and the permission of the
execution's path. For each activity, we need to describe the
activity's duration, task priority and the conditions of
activity's implementation, to ensure the workflow can be run
accurately in the actual operation.