DATA SYNCHRONIZING APPARATUS USING COMMANDS

摘要

When data is changed at an arbitrary timing and synchronized among a plurality of terminals that are online to an arbitrary terminal at an arbitrary timing, there exist problems as follows: (1) when there exist three or more terminals, no appropriate data synchronization can be effected; (2) no conflicts of change commands can be found; (3) change commands issued by a plurality of terminals are not allowed to take effect on data in a correct order; and (4) a result from a solution of conflicts of change commands cannot be appropriately transferred to other terminals. In order to solve the foregoing problems, when data has been changed, a change command is generated, and not only the change command of the local terminal but also a change command received from another terminal is stored. When synchronization is established among terminals, not only the change command of the local terminal but also the stored change command of the other terminal is transferred. Furthermore, the information indicative of the status at issuance of a change command (firing condition information) is stored for each of change commands, and when a change command is caused to take effect on the data, this information is referred to so as to determine whether to cause the change command to take effect on the data.