Several real-time applications include tasks in which the output must be produced at precise time instants, rather than 'within' a deadline, and the overall system performance significantly degrades when the task is executed too late or too early with respect to the desired time. This paper illustrates one of such applications and takes it as a reference case study to propose a general approach to show how to derive the timing constraints from the application requirements, how to implement the application on top of a realtime kernel, identifying the operating system features necessary to enforce such constraints, and how to analyze the schedulability of the task set. A set of experimental results are also presented to validate the proposed approach.