Control method, control system, first server, and data structure

1. A control method executed by a first server of a plurality of servers in a system including one or more Internet of Things (IoT) devices and the plurality of servers communicative with the one or more IoT devices via a network, the control method comprising:

obtaining first transaction data including operation notification information and time information from each of the one or more IoT devices, the operation notification information including identification information on the IoT device and a notification indicating that the IoT device is operating normally, the time information indicating a time when the IoT device has obtained the operation notification information;

transferring the first transaction data obtained, to a plurality of second servers that are the plurality of servers other than the first server;

executing, together with the plurality of second servers, a first consensus algorithm for an agreement on an authenticity of the first transaction data; and

recording a block containing the first transaction data in a distributed ledger of the first server, when the authenticity of the first transaction data is verified by the first consensus algorithm, wherein

the system further includes a terminal communicative with the plurality of servers via the network and used by a user, and

the control method further comprises:

reading out status information indicating whether each of the one or more IoT devices is available based on whether the operation notification information has been obtained within a predetermined time, when a user request by the user inquiring whether an IoT device of the one or more IoT devices is available is received from the terminal; and

sending, to the terminal, a first signal indicating that the IoT device is permitted for use under a predetermined condition, when the IoT device is determined to be available based on the status information read out.

2. The control method according to claim 1 , further comprising:

sending, to the terminal, a signal indicating that the IoT device is not permitted for use, when the IoT device is determined to be unavailable based on the status information read out.

3. The control method according to claim 1 , further comprising:

transferring, to the plurality of second servers, second transaction data indicating a purchase of a right to use the IoT device, when the second transaction data is obtained from the terminal;

executing, together with the plurality of second servers, a second consensus algorithm for an agreement on an authenticity of the second transaction data; and

recording a block containing the second transaction data in the distributed ledger of the first server, when the authenticity of the second transaction data is verified by the second consensus algorithm.

4. The control method according to claim 3 , wherein

the status information further includes an open/closed status of the IoT device, and

the control method further comprising:

obtaining, from the terminal, third transaction data indicating a request to unlock the IoT device based on the right to use;

transferring the third transaction data obtained, to the plurality of second servers;

executing, together with the plurality of second servers, a third consensus algorithm for an agreement on an authenticity of the third transaction data; and

recording a block containing the third transaction data in the distributed ledger of the first server to change the open/closed status of the IoT device included in the status information, when the authenticity of the third transaction data is verified by the third consensus algorithm.

5. The control method according to claim 1 , further comprising:

reading out the first transaction data recorded in the distributed ledger;

generating the status information based on the first transaction data read out, and writing the status information on a memory of the first server; and

reading out the status information on the memory, when the user request is received from the terminal.

6. The control method according to claim 1 , wherein

the time information is a timestamp at a time of obtaining the notification indicating that the IoT device is operating normally or a sequence number.

7. The control method according to claim 1 , further comprising:

executing a smart contract stored in the distributed ledger to generate the first transaction data, when the operation notification information is obtained.

8. A control system, comprising:

one or more IoT devices; and

a plurality of servers communicative with the one or more IoT devices via a network, wherein

a first server of the plurality of servers:

obtains first transaction data including operation notification information and time information from each of the one or more IoT devices, the operation notification information including identification information on the IoT device and a notification indicating that the IoT device is operating normally, the time information indicating a time when the IoT device has obtained the operation notification information;

transfers the first transaction data obtained, to a plurality of second servers that are the plurality of servers other than the first server;

executes, together with the plurality of second servers, a first consensus algorithm for an agreement on an authenticity of the first transaction data; and

records a block containing the first transaction data in a distributed ledger of the first server, when the authenticity of the first transaction data is verified by the first consensus algorithm, wherein

the control system further includes a terminal communicative with the plurality of servers via the network and used by a user, and

the first server further:

reads out status information indicating whether each of the one or more IoT devices is available based on whether the operation notification information has been obtained within a predetermined time, when a user request by the user inquiring whether an IoT device of the one or more IoT devices is available is received from the terminal; and

sends, to the terminal, a first signal indicating that the IoT device is permitted for use under a predetermined condition, when the IoT device is determined to be available based on the status information read out.

9. A first server of a plurality of servers in a system including one or more IoT devices and the plurality of servers communicative with the one or more IoT devices via a network, the first server comprising:

a processor;

a memory that stores a program causing the processor to execute processing; and

a storage device that stores a distributed ledger storing a smart contract, wherein

the processor executes the smart contract stored in the distributed ledger to obtain first transaction data including operation notification information and time information from each of the one or more IoT devices, the operation notification information including identification information on the IoT device and a notification indicating that the IoT device is operating normally, the time information indicating a time when the IoT device has obtained the operation notification information, and

by executing the program stored on the memory, the processor:

transfers the first transaction data obtained, to a plurality of second servers that are the plurality of servers other than the first server;

executes, together with the plurality of second servers, a first consensus algorithm for an agreement on an authenticity of the first transaction data; and

records a block containing the first transaction data in the distributed ledger of the first server, when the authenticity of the first transaction data is verified by the first consensus algorithm, wherein

the system further includes a terminal communicative with the plurality of servers via the network and used by a user, and

by executing the program stored on the memory, the processor further:

reads out status information indicating whether each of the one or more IoT devices is available based on whether the operation notification information has been obtained within a predetermined time, when a user request by the user inquiring whether an IoT device of the one or more IoT devices is available is received from the terminal; and

sends, to the terminal, a first signal indicating that the IoT device is permitted for use under a predetermined condition, when the IoT device is determined to be available based on the status information read out.

10. A data structure used for a block to be recorded in a distributed ledger, in a system including one or more IoT devices and a plurality of servers communicative with the one or more IoT devices via a network, the data structure comprising:

first transaction data including operation notification information and time information, the operation notification information including identification information on each of the one or more IoT devices and a notification indicating that the IoT device is operating normally, the time information indicating a time of obtaining the operation notification information, wherein

the first transaction data is obtained by a first server of the plurality of servers through execution of a smart contract stored in the distributed ledger,

the first transaction data obtained is contained in the block so as to be recorded in the distributed ledger,

the system further includes a terminal communicative with the plurality of servers via the network and used by a user, and

the first server:

reads out status information indicating whether each of the one or more IoT devices is available based on whether the operation notification information has been obtained within a predetermined time, when a user request by the user inquiring whether an IoT device of the one or more IoT devices is available is received from the terminal; and

sends, to the terminal, a first signal indicating that the IoT device is permitted for use under a predetermined condition, when the IoT device is determined to be available based on the status information read out.