I am new to activiti. I have read about the timer event. i creating a workflow say vacation request. if i submit the vacation from date and to date, it should go to group A to schedule the task. As soon as it is scheduled , process should start from vacation start date. Then the request goes to group B. They can only can the request. If they didnt cancel the request ,at the end date, process should be completed. How can i achieve this?