Sending apparatus, sending method and communication system

A data sending apparatus, comprising:

• a storage that stores a plurality of data;
• a sending unit that externally sends data stored by the storage 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;
• and
• a fraction unit that fractionates a clump of data belonging to the group selected by the selection unit into pieces of data, wherein
• 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, and
• 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, at every said interval.

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 classification;
• updating data belonging to a data category obtained by the categorization, among data belonging to the group obtained by the selection, at every said sending interval;
• fractionating a clump of data belonging to the group obtained by the selection into pieces of data;
• and
• sending to said another data sending apparatus a piece of data generated from the clump of data that comprises updated data and is fractionated into, at every said sending interval.

A data communication system, comprising:

• a plurality of sending apparatuses, each of which externally sends data, wherein
• each sending apparatus comprises:
• 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;
• and
• 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, at every said interval, and
• data contents stored by the storage are synchronized among the plurality of sending apparatuses.