| 摘要 |
PROBLEM TO BE SOLVED: To notify a monitoring request source of a fact that the connection state of a monitored terminal device is changed, every time the connection state of the monitored terminal device is changed without causing an increase in load on a presence monitoring apparatus, even if the number of connection state monitoring request sources increases, in a peer-to-peer communication system. SOLUTION: A monitoring request source terminal device 1A notifies the presence monitoring apparatus 2 of a request of monitoring a monitored terminal device 1B. If the own connection state is changed, the device 1B notifies the device 2 of that fact. Upon receiving the connection state notice from the device 1B, the presence monitoring device 2 transmits the information of a monitoring request source device 1A to the device 1B. The device 1B registers the received information of the device 1A. Every time the connection state is changed, the device 1B directly transmits the fact to the device 1A in which the connection state is registered. A user terminal device 1A checks the connection state of the device 1B on the basis of the received connection state notification, and immediately starts communication with the device 1B if the device 1B is in a connection state and the connection is required. COPYRIGHT: (C)2005,JPO&NCIPI
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