Data synchronization system, data synchronization method, data center, and client terminal

摘要

There is provided a data synchronization system, data synchronization method, data center, and client terminal that allow a client terminal to determine whether data held by the client terminal is up-to-date and allow synchronization between a server and the client to be maintained at low costs in a case where synchronization between data in the server and data in the client terminal is provided. ;The data synchronization system for keeping the sameness between data in a client terminal 10 and data in a data server 20 through a communication link comprises a synchronization data transmitter 25 for sending to the client terminal 10 data to be kept same as data in the client terminal 10, a synchronization signal output module 33 for sending a synchronization signal for checking the sameness to the client terminal 10 at predetermined timing, and a synchronization signal transmission controller 23 for controlling the transmission of the synchronization signal by the synchronization signal output module 33 based on the result of the synchronization signal transmission by the synchronization signal output module 33.