Method of transmitting data of usb device to server, and client terminal performing the method

A client terminal comprising:

• a USB interface unit connected to a plurality of USB devices;
• a communication unit configured to communicate with a server;
• and
• a controller configured to receive a data request message for requesting data of a USB device among the plurality of USB devices, from the server, the data request message including information about a size of data that is to be read from the USB device, to acquire data corresponding to the size of data included in the data request message, from the USB device, to decide a size of data that is able to be additionally transmitted from the USB device, according to operation states of the other USB devices connected to the client terminal, to generate a data transmission completion message to the server through the communication unit, wherein the data transmission completion message includes information about the size of data that is able to be additionally transmitted and the data acquired from the USB device.