A client device includes a memory comprising a buffer for buffering data having real-time constraints and a hardware-based processor comprising digital logic circuitry. The processor is configured to execute a real-time application configured to determine times during which the data will be available for download, determine a time at which the data is needed to prevent a buffer underrun for the buffer, and when the data is available, send a request for the data and deadline information representative of the time at which the data is needed to avoid the buffer underrun. In this manner, a sending device can prioritize delivery of the requested data to prevent the buffer underrun for the client device.