Communication device, method for communication and relay system

A method for communication of a communication device, the method comprising:

• establishing sessions with a first device, the sessions being logical connections in communication;
• establishing sessions with a second device;
• collecting a limited maximum number of sessions established with the second device and a number of second devices connected by using the established sessions;
• calculating an allowable number of sessions to be established by the communication device itself, based on the collected limited maximum number of sessions and the number of the second devices;
• in a case of detecting a loan request from another communication device, lending the another communication device a session not yet established within the calculated allowable number of sessions;
• establishing sessions with the second device within the calculated allowable number of sessions;
• deciding whether an unused session remains in the established sessions for a command generated by the first device to be exchanged with the second device, the unused session being a previously established session in which a previous command generated by the first device has been exchanged with the second device;
• in a case of identifying that the unused session remains in the established sessions when the command is received,
• exchanging the command with the second device by the unused session;
• and
• communicating messages to the second device by the unused session at particular intervals before a timeout period of the second device passes to continuously maintain the unused session with the second device,
• wherein a signal is relayed between the first device performing as a connection start terminal and the second device performing as a connection end device.

A relay system comprising:

• a first device configured to run at least one application program;
• a second device configured to carry out a first command issued by a first application program;
• and
• a third device configured to relay commands between the first device and the second device,
• wherein the first device includes a first processor configured to execute a first procedure, the first procedure including:
• generating the first command issued by the first application program,
• deciding whether an unused session, remains in first sessions established between the first device and the third device for a second command issued by a second application program, based on a destination of the second command, the unused session being a previously established session in which a previous command generated by the first application program has been exchanged with the second device,
• in a case of identifying that the unused session remains in the first sessions,
• exchanging the second command with the second device by the unused session, and
• communicating messages to the third device by the unused session remaining in the first sessions at particular intervals before a timeout period of the second device passes to continuously maintain the unused session in the first sessions with the second device,
• wherein the third device includes a second processor configured to execute a second procedure, the second procedure including:
• receiving a third command in second sessions established between the first device and the third device,
• collecting a limited maximum number of sessions established with the second device and a number of second devices connected by using the established second sessions;
• calculating an allowable number of sessions to be established by the third device itself, based on the collected limited maximum number of sessions and the number of the second devices;
• in a case of detecting a loan request from another third device, lending the another third device a session not yet established within the calculated allowable number of second sessions;
• establishing second sessions with the second device within the calculated allowable number of sessions;
• deciding whether an unused session remains in the second sessions established between the second device and the third device for the third command based on a destination of the third command,
• in a case of identifying that the unused session remains in the second sessions,
• exchanging the third command with the second device by the unused session;
• and
• communicating messages to the second device by the unused session remaining in the second sessions at particular intervals before a timeout period of the second device passes to continuously maintain the unused session in the second sessions with the second device,
• wherein a signal is relayed between the first device performing as a connection start terminal and the second device performing as a connection end device.