Sending apparatus, sending method and communication system

A sending method, with using a data sending apparatus having a storage that stores a plurality of data, for sending data stored by the storage at a predetermined sending interval to another data sending apparatus, comprising steps of:

• classifying the plurality of data stored by the storage into a plurality of groups;
• categorizing data belonging to each classified group into data categories;
• selecting a group from the plurality of groups obtained by the classifying;
• updating data belonging to a data category obtained by the categorizing, among data belonging to the group obtained by the selecting, at every said sending interval;
• fractionating a clump of data belonging to the group obtained by the selecting into pieces of data;
• and
• sending to said another data sending apparatus a piece of data generated from the fractionated clump of data that comprises the updated data, and sending each piece of data at every said interval under a sending completion allowable time previously set for the group selected.

A data communication system, comprising:

• a plurality of sending apparatuses, each of which externally sends data, wherein
• each sending apparatus comprises:
• a processor and a memory;
• a receiving unit that receives data sent from another sending apparatus;
• a storage that stores a plurality of data;
• a sending unit that sends data stored by the storage to another sending apparatus at a predetermined interval;
• an update unit that updates data stored by the storage;
• a group classification unit that classifies the plurality of data stored by the storage into a plurality of groups;
• a data categorization unit that categorizes data belonging to each group classified by the group classification unit into data categories;
• a selection unit that selects a group from the plurality of groups classified by the group classification unit;
• a fraction unit that fractionates a clump of data belonging to the group selected by the selection unit into pieces of data,
• the update unit updates data belonging to a predetermined data category categorized by the data categorization unit among data belonging to a group selected by the selection unit, at every said interval,
• the sending unit sends a piece of data that is obtained by the fraction unit fractionating the clump of data which comprises data updated by the update unit, wherein the sending unit sends each piece of data at every said interval under a sending completion allowable time previously set for the group selected by the selection unit, and
• data contents stored by the storage are synchronized among the plurality of sending apparatuses.