Control system, communication system, computer program, controlling method, and computer program product

A controlling method performed in a controller including processing circuitry that manages state information of each communication terminal, which indicates a state of connection between the communication terminal and the controller, the controlling method comprising:

• updating, when the state of connection between a first communication terminal and the controller is changed, state information of the first communication terminal;
• determining whether another controller is working in inter-node cooperation with the controller, and only when it is determined that the another controller is working in the inter-node cooperation, transmitting information of the changed state of connection to the another controller;
• receiving, when the state of connection between a second communication terminal and the another controller is changed and the another controller determines that the another controller and the controller are working in the inter-node cooperation, changed state information of the second communication terminal, which indicates a state of connection between the second communication terminal and the another controller after being changed, from the another controller;
• updating the state information of the second communication terminal based on the received changed state information received in the receiving step;
• and
• controlling a session between the communication terminals based on the state information.

A computer program product comprising a non-transitory computer-readable medium containing a computer program, wherein the computer program causes a computer that manages state information of each communication terminal, which indicates a state of connection between the communication terminal and the computer, to perform:

• updating, when the state of connection between a first communication terminal and the computer is changed, state information of the first communication terminal managed by the computer;
• determining whether another controller is working in inter-node cooperation with the controller, and only when it is determined that the another controller is working in the inter-node cooperation, transmitting information of the changed state of connection to the another controller;
• receiving, when the state of connection between a second communication terminal and the another computer is changed and the another controller determines that the another controller and the controller are working in the inter-node cooperation, changed state information of the second communication terminal, which indicates a state of connection between the second communication terminal and the another computer after being changed, from the another computer;
• updating the state information of the second communication terminal managed by the computer based on the received changed state information received in the receiving step;
• and
• controlling a session between the communication terminals based on the state information managed by the computer.