Notification method, connection apparatus, communication method, and program

A notification method, wherein a first connection apparatus is connected to a first network and a second network, and a second connection apparatus is connected to the second network and a third network, for notifying an apparatus connected to the third network of information regarding a device connected to the first network, said method comprising:

• the first connection apparatus receiving a message which is broadcast periodically by the device connected to the first network, obtaining information regarding the device based on predetermined information included in the broadcast message, and transmitting a message including the information regarding the device to the second connection apparatus via the second network in a case where the information regarding the device is not stored in a table in the first connection apparatus for storing information regarding devices, wherein the predetermined information is storage location information of a storage location of the information regarding the device, and the information regarding the device is obtained from the storage location based on the storage location information;
• the second connection apparatus receiving the message transmitted from the first connection apparatus via the second network, and transmitting, based on the message received from the first connection apparatus, a message indicating that the device is available onto the third network;
• the first connection apparatus transmitting a predetermined message to the second connection apparatus via the second network in a case where the message broadcast by the device indicates that the device is unavailable;
• and
• the second connection apparatus transmitting a message indicating that the device is unavailable to the third network in a case where the predetermined message is received from the first connection apparatus.