JbpmConfiguration：configuration of one jBPM instance.
JbpmContext：is used to surround persistent operations to processes.
ProcessDefinition：
ProcessInstance：is one execution of a
ProcessDefinition. To create a new process execution of a process definition, just use the
ProcessInstance(ProcessDefinition).
ContextInstance：maintains all the key-variable pairs for a process instance
TaskMgmtSession:
findTaskInstances(java.lang.String actorId) get the tasllist for a given actor.（根据角色得到此角色的任务列表）
loadTaskInstance(long taskInstanceId) get the task instance for a given task instance-id.（根据实例ID获得任务实例）
TaskInstance:
end() marks this task as done.
end(java.lang.String transitionName) marks this task as done and specifies the name of a transition leaving the task-node for the case that the completion of this task instances triggers a signal on the token.