Briefly describes the working principle of the vending machine?

Vending machine principle of work: first, choose goods, vending machine procedure will apply to the backend server launch collection for qr code ( WeChat, pay treasure or other electronic payment) , qr code displayed on the vending machine screen directly. 2, after customers scan code, backend server will query the collection account is not received the money, if received, backend server will send a shipment to vending machine instructions, vending machine according to the instructions for shipment. Intelligent vending machine functions, principle is very complicated, some don't need payment based on the input code to pick up the goods can shipment, principle is customer input delivery code or lottery ticket code, vending machine to send the code to pick up the goods to the background server, a backend server to verify code to pick up the goods, and send the corresponding shipping instructions to the vending machine, vending machine according to the instruction from the corresponding goods.