Instruction system, instruction device, method, and program

An instruction device includes: an acquiring unit configured to acquire provided metadata, which is attribute information relating to one or more attributes of sensing data, the provided metadata having one or more hierarchy levels that contain information shared by a plurality of sensors; an acquiring unit configured to acquire usable metadata, which is attribute information relating to one or more attributes of an application; a matching unit configured to perform matching between the provided metadata and the usable metadata for each hierarchy level, calculate, for each hierarchy level, an inter-level matching degree that indicates a degree of matching in the hierarchy level, and extract a sensor capable of providing the sensing data that satisfies a request of the application, based on an overall matching degree; and an instruction unit configured to transmit a data flow control instruction that specifies the application and the extracted sensor.