Message transmitting and receiving method, communication apparatus, and program

1. A message transmitting and receiving method performed by a communication apparatus, the communication apparatus comprising a processor and a storage unit configured to store a middleware and a library, the middleware, when executed by the processor, causing the processor to operate as a middleware unit configured to manage a message published by a publisher in a publish/subscribe system in which a message is exchanged between the publisher and a subscriber via a broker, the library including functions configured to provide the broker, the method comprising:

performing, by the middleware unit, subscribing on the broker by setting a callback function;

upon receipt of a first message published by a first device, passing, by the broker, the first message to the middleware unit by calling the callback function;

transmitting, by the middleware unit, the first message to a second device in response to receipt of the first message from the broker;

when the callback function is called, returning, by the middleware unit, a function in which whether or not predetermined processing including storage of the first message has succeeded is assigned to a return value; and

transmitting to the first device information indicating whether or not the first message has arrived at the middleware unit, depending on the function returned by the middleware unit.

2. The message transmitting and receiving method according to claim 1 , further comprising:

receiving, by the middleware unit, control information for controlling the first device from a third device; and

publishing, by the middleware unit, a second message including the control information with respect to the broker by performing a function call.

3. The message transmitting and receiving method according to claim 2 , further comprising returning, by the broker, a function in which whether or not the second message has arrived at the first device is assigned to a return value.

4. The message transmitting and receiving method according to claim 1 , further comprising acquiring, by the middleware unit, device status information indicating a status of the first device from the broker by performing a function call.

5. The message transmitting and receiving method according to claim 4 , wherein the device status information includes session information indicating a status of connection with the first device or active-and-inactive information indicating an active-and-inactive status of the first device.

6. A non-transitory computer readable medium storing a computer program, the computer program comprising a middleware and a library, the middleware, when executed by a computer, causing the computer to operate as a middleware unit configured to manage a message published by a publisher in a publish/subscribe system in which a message is exchanged between the publisher and a subscriber via a broker, the library including functions configured to provide the broker wherein the computer program is executed by the computer to provide the steps of:

performing, by a middleware unit, subscribing on the broker by setting a callback function;

upon receipt of a first message published by a first device, passing, by the broker, the first message to the middleware unit by calling the callback function;

transmitting, by the middleware unit, the first message to a second device in response to receipt of the first message from the broker;

when the callback function is called, returning, by the middleware unit, a function in which whether or not predetermined processing including storage of the first message has succeeded is assigned to a return value; and

transmitting to the first device information indicating whether or not the first message has arrived at the middleware unit, depending on the function returned by the middleware unit.

7. The non-transitory computer readable medium according to claim 6 , further comprising: receiving, by the middleware unit, control information for controlling the first device from a third device; and

publishing, by the middleware unit, a second message including the control information with respect to the broker by performing a function call.

8. The non-transitory computer readable medium to claim 7 further comprising returning, by the broker, a function in which whether or not the second message has arrived at the first device is assigned to a return value.

9. The non-transitory computer readable medium according to claim 6 , further

comprising acquiring, by the middleware unit, device status information indicating a status of the first device from the broker by performing a function call.

10. The non-transitory computer readable medium according to claim 9 , wherein the device status information includes session information indicating a status of connection with the first device or active-and-inactive information indicating an active-and-inactive status of the first device.

11. A communication apparatus comprising:

a processor;

a memory coupled to the processor, the memory being configured to store a middleware and a library, the middleware, when executed by the processor, causing the processor to operate as a middleware unit configured to manage a message published by a publisher in a publish/subscribe system in which a message is exchanged between the publisher and a subscriber via a broker,

the library including functions configured to provide the broker,

wherein the middleware unit is further configured to perform subscribing on the broker by setting a callback function,

wherein the broker is configured to, upon receipt of a first message published by a first device, pass the first message to the middleware unit by calling the callback function, and

wherein the middleware unit is configured to, in response to receipt of the first message from the broker, transmit the first message to a second device,

wherein the middleware unit is configured to, when the callback function is called, return a function in which whether or not predetermined processing including storage of the first message has succeeded is assigned to a return value, and

wherein the broker is configured to transmit to the first device information indicating whether or not the first message has arrived at the middleware unit, depending on the function returned by the middleware unit.

12. The communication apparatus according to claim 11 , wherein the middleware unit is configured to:

receive control information for controlling the first device from a third device; and

publish a second message including the control information with respect to the broker by performing a function call.

13. The communication apparatus according to claim 12 wherein the broker is further configured to return a function in which whether or not the second message has arrived at the first device is assigned to a return value.

14. The communication apparatus according to claim 11 , wherein the middleware unit is further configured to acquire device status information indicating a status of the first device from the broker by performing a function call.

15. The communication apparatus according to claim 14 , wherein the device status information includes session information indicating a status of connection with the first device or active-and-inactive information indicating an active-and-inactive status of the first device.