A node device group comprising a plurality of node devices (20, 20A, 20B, 20C), the node device group being adapted to be placed in a network system, wherein at least one computer apparatus and the plurality of node devices (20, 20A, 20B, 20C) are communicatively connectable to each other via a network, each of the plurality of node devices (20, 20A, 20B, 20C) is accessible by one or more sensor devices (30, 30A-30G) via a wireless communication or wired communication, wherein each node device of the plurality of node devices (20, 20A, 20B, 20C) is adapted to acquire sensor data from the one or more sensor devices connected to the respective node device and to save the sensor data in a sensor data storage section included in the respective node device, wherein a first node device is adapted to receive from the computer apparatus an information acquisition request for all of the sensor data from any one or more of the one or more sensor devices (30, 30A-30G), said first node device being any of the plurality of node devices (20, 20A, 20B, 20C), wherein each of the plurality of node devices (20, 20A, 20B, 20C) comprises: a sensor data search section for searching the sensor data storage sections of the plurality of node devices (20, 20A, 20B, 20C) for the sensor data according to the information acquisition request and acquiring the sensor data, wherein the searching comprises: - when the respective node device is the first node device, searching, in response to the information acquisition request, the sensor data storage section of the first node device for the sensor data according to the information acquisition request and acquiring the corresponding sensor data, while issuing the information acquisition request to the other node devices of the plurality of node devices (20, 20A, 20B, 20C), and - when the respective node device is one of the other node devices, searching, in response to the information acquisition request made by the first node device, the sensor data storage section of the respective node device for the sensor data according to the information acquisition request and acquiring the corresponding sensor data; and an information transmission section for transmitting the sensor data acquired by the sensor data search section, wherein the transmitting comprises: - when the respective node device is one of the other node devices, transmitting, to the first node device, a reply comprising either the acquired sensor data or a non-availability indication when the sensor data storage section of the respective node device does not comprise sensor data according to the information acquisition request, and - when the respective node device is the first node device, transmitting, to the computer apparatus after receiving the replies from the other node devices, the sensor data acquired by the first node, and the sensor data and non-availability indications comprised in the replies of the other nodes devices. - when the respective node device is the first node device, searching, in response to the information acquisition request, the sensor data storage section of the first node device for the sensor data according to the information acquisition request and acquiring the corresponding sensor data, while issuing the information acquisition request to the other node devices of the plurality of node devices (20, 20A, 20B, 20C), and - when the respective node device is one of the other node devices, searching, in response to the information acquisition request made by the first node device, the sensor data storage section of the respective node device for the sensor data according to the information acquisition request and acquiring the corresponding sensor data; and an information transmission section for transmitting the sensor data acquired by the sensor data search section, wherein the transmitting comprises: - when the respective node device is one of the other node devices, transmitting, to the first node device, a reply comprising either the acquired sensor data or a non-availability indication when the sensor data storage section of the respective node device does not comprise sensor data according to the information acquisition request, and - when the respective node device is the first node device, transmitting, to the computer apparatus after receiving the replies from the other node devices, the sensor data acquired by the first node, and the sensor data and non-availability indications comprised in the replies of the other nodes devices. - when the respective node device is one of the other node devices, transmitting, to the first node device, a reply comprising either the acquired sensor data or a non-availability indication when the sensor data storage section of the respective node device does not comprise sensor data according to the information acquisition request, and - when the respective node device is the first node device, transmitting, to the computer apparatus after receiving the replies from the other node devices, the sensor data acquired by the first node, and the sensor data and non-availability indications comprised in the replies of the other nodes devices.