Patent ID: 8015269

Claim:
A node device in an information sharing system including a plurality of node devices mutually connectable through a network, the plurality of node devices saving shared information which is used in common with the plurality of node devices, the node device transmits predetermined data to other node devices, the node device comprising: a first version information saving unit that saves version information indicative of a version of shared information saved by the node device; a data transmission unit that transmits data and version information corresponding to the transmitted data to the other node devices; a data receiving unit that receives the data and version information which are transmitted from one of the plurality of node devices; a first version judgment unit that judges whether the version information saved in the first version information saving unit is older than the version information received by the data receiving unit; a second version information saving unit that saves the version information received by the data receiving unit, in response to the first version judgment unit judging that the version information saved in the first version information saving unit is older than the version information received by the data receiving unit; wherein the second version information saving unit contains a predetermined number; and wherein the predetermined number represents a number of times the first version judgment unit has determined the version information saved in the first version information saving unit is older than the version information received by the data receiving unit, wherein the version information received is transmitted by a different one of the plurality node devices; a second version judgment unit that judges whether the number of version information saved in the second version information saving unit reaches the predetermined number, wherein the predetermined number is two or more, and a shared information update unit that updates the shared information saved in the first version information saving unit to a new version shared information, in response to the second version judgment unit judging the number of version information saved in the second version information saving unit reaches the predetermined number.