| 摘要 |
PROBLEM TO BE SOLVED: To provide a directory service, by which information can be reserved and registered and history can be retrieved. SOLUTION: An information updating processing part 2 adds validity information (starting date and ending date) of information possible to be updated among information possible to be registered to that information and registers the information on an information database 1. While referring to the validity information, a history retrieving part 8 extracts information effective at a time point designated in an information acquisition request or effective within a designated period out of the information database 1 and answers. |
