A two-dimensional code reader repeats a cycle of ordinary code-reading processes such as taking an image of an optical data code, extracting a two-dimensional code from the image and decoding optical data of the two-dimensional code in the image. A system ceiling 50 is attached to a ceiling surface 25 to send out cooling air to a cooling area 2 from a vent 31a of an indoor unit 31 of an air conditioning device disposed in a container 1, and a draft air duct is defined by the system ceiling 50, a down-wall 51 and the ceiling surface 25. A software defined environment may includes an application program interface used to program the flow of the network traffic.