org.activiti.engine
接口 
EngineServices
FormService
HistoryService
IdentityService
ManagementService
ProcessEngine
ProcessEngineInfo
ProcessEngineLifecycleListener
RepositoryService
RuntimeService
TaskService
 
ProcessEngineConfiguration
ProcessEngines
异常 
ActivitiClassLoadingException
ActivitiException
ActivitiIllegalArgumentException
ActivitiObjectNotFoundException
ActivitiOptimisticLockingException
ActivitiTaskAlreadyClaimedException
ActivitiWrongDbException
JobNotFoundException