Patent ID: 7853718

Claim:
A node device included in an information delivery system, which includes a plurality of node devices enabled to mutually communicate through a network, wherein transfer destination node information indicative of a node device to which a message received from another node device is transferred, is memorized in the node devices, and at least one piece of delivery information is stored in the node devices in a distributed manner, wherein a registration message including storage source node information indicative of one node device storing the delivery information is sent out of the one node device in a case where the delivery information is stored in the one node device, the registration message is transferred up to a node device for managing a location of delivery information by a plurality of relay node devices in accordance with the transfer destination node information, and the storage source node information is memorized in the relay node devices and the node device for managing the location of delivery information, wherein one of the relay node devices included in the information delivery system, comprising: a memory unit that memorizes the transfer destination node information and the storage source node information; a node information change detection unit that detects a change of the transfer destination node information; a storage source node information extraction unit that extracts the storage source node information, which is included in the registration message transferred in accordance with the transfer destination node information before the change, from the memory unit; a reregistration message generation unit that generates a reregistration message including the storage source node information thus extracted; and a reregistration message sending unit that sends thus generated reregistration message in accordance with the transfer destination node information after the change.