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Typically, we would have a Deadline set at the intended activity itself like the following diagram.
Figure 1: Asynchronous deadline set at "Approve Leave" activity to "Send Reminder"
It is a very simple and straight forward design we got above but there may be a need to send out reminder at an interval, not just once. Therefore, we may design our workflow in such a manner like the one below.
Figure 2: Repetitively triggering "Send Reminder" using a waiting activity "Wait for Timeout"
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