I want to generate an alert or notification in the following scenario about absence management.

Scenario:

An employee applies for Vacation leave for 10 days starting on say Date 1 to Date 10.

IN his absence the employee will be replaced on his day to duties by say a Replacing_employee.

My application should generate mail/notication to te Replacing_employee that he/she will be replacing the absentee for 10 days.

Which types of alert should be created – a periodic one (coz he needs to have a single notification per absenting period and absenting employee or event based alert

Thanks