To improve convenience to a client in an application.

A server 100 generates a session information object 122, which manages session information, and a data information object 123, which manages transmission data from a client, on a storage part 120, gives each of the objects identifiers, which uniquely identify the respective objects, and information which manages the terms of validity on the storage part 120, and invalidates an object whose validity expires. The information transmitted and received between the server 100 and a client includes information on each identifier, and the server 100 determines whether an object corresponding to an identifier received from the client is valid. If the session information object 122 is invalid and the data information object 123 is valid, the server 100 newly generates a session information object 122 or updates the previous session information object 122.

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