A notification message receiving apparatus comprising: a user datagram protocol decoder configured: - to decode a user datagram protocol packet in accordance with an UDP; and - to output a real-time protocol packet; an RTP decoder configured: - to decode a real-time protocol packet; and - to acquire, from the RTP packet, data of a plurality of notification messages which are delivered with time constraints associated with audio or video streams, wherein the RTP packet includes first information describing a notification type of each of the plurality of notification messages and second information indicating that the plurality of notification messages is aggregated within the RTP packet, wherein generic notification message parts of the plurality of notification messages which are delivered with time constraints are included in an RTP payload format header in the RTP packet and remaining parts of the plurality of notification messages are included in a payload in the RTP packet; and an file delivery over unidirectional transport (FLUTE) decoder configured: - to decode an FDT instance and FLUTE transport object in accordance with FLUTE; and - to acquire data of a plurality of notification messages which are delivered without time constraints associated with audio or video streams. a user datagram protocol decoder configured: - to decode a user datagram protocol packet in accordance with an UDP; and - to output a real-time protocol packet; - to decode a user datagram protocol packet in accordance with an UDP; and - to output a real-time protocol packet; an RTP decoder configured: - to decode a real-time protocol packet; and - to acquire, from the RTP packet, data of a plurality of notification messages which are delivered with time constraints associated with audio or video streams, wherein the RTP packet includes first information describing a notification type of each of the plurality of notification messages and second information indicating that the plurality of notification messages is aggregated within the RTP packet, wherein generic notification message parts of the plurality of notification messages which are delivered with time constraints are included in an RTP payload format header in the RTP packet and remaining parts of the plurality of notification messages are included in a payload in the RTP packet; and - to decode a real-time protocol packet; and - to acquire, from the RTP packet, data of a plurality of notification messages which are delivered with time constraints associated with audio or video streams, wherein the RTP packet includes first information describing a notification type of each of the plurality of notification messages and second information indicating that the plurality of notification messages is aggregated within the RTP packet, wherein generic notification message parts of the plurality of notification messages which are delivered with time constraints are included in an RTP payload format header in the RTP packet and remaining parts of the plurality of notification messages are included in a payload in the RTP packet; and an file delivery over unidirectional transport (FLUTE) decoder configured: - to decode an FDT instance and FLUTE transport object in accordance with FLUTE; and - to acquire data of a plurality of notification messages which are delivered without time constraints associated with audio or video streams. - to decode an FDT instance and FLUTE transport object in accordance with FLUTE; and - to acquire data of a plurality of notification messages which are delivered without time constraints associated with audio or video streams.