| 摘要 |
A transmitting de vice (300) constituting a data cache system is provided with a data acquisition unit (315) for acquiring numerical data transmitted from a server, the data representing the quantity of a commodity or a service capable of being transacted. The transmitting device (300) is provided with a preserving unit (320) for preserving the acquired numerical data as cache data in an information storage unit (390), and a request acquisition unit (330) for acquiring a request asking for output of a quantity. The transmitting device (300) is provided with a determination unit (350) which, when the request is acquired, determines, on the basis of an elapsed time from a time of day at which the cache data was received or preserved and the quantity represented by the cache data, whether the cache data is valid. The data acquisition unit (315) receives new numerical data from the server when the cache data is determined to be invalid, and the preserving unit (320) preserves the new numerical data as new cache data in the information storage unit (390). |
