If you want to execute something when a predefined time reached…
For Service Task, you can use the Intermediate Boundary Event. For example, add an Intermediate Boundary Event to a Service Task(let’s call it service1) and set a time, and add a transition from the Intermediate Boundary Event to another Service Task(let’s call it service2), then when the service1 execute longer than the specified time, service2 will be invoked. More detail please refer to <BPM_Process_Development_Help> chapter 12 Event.
For User Task, you can use the Task Event, more detail please refer to <BPM_Task_Development_Help> chapter 10 Configuring Tasks.
Hope it helps.
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