A device set may interoperate to perform an action, such as providing a message to a user or storing photos taken by a user. Since the water drop with oil film is supplied to a work piece through a top nozzle and an in-tool passage, the water drop with oil film is generated at an extremely close location to a tool, and therefore, responsiveness when supplying the water drop with oil film to the work piece can be enhanced. The network further includes a plurality of gateway nodes. Speed is achieved using a shared memory map so that the dedicated processor can quickly retrieve data provided by one of the other processors. Moreover, during start-up of the system, the control mode is changed to open the pressure regulating valve, thereby limiting the rate of increase in pressure just after the generation of reformed gas has started.