Pay-as-you-go billing system and method in connectionless communication

When an accounting process is performed through connectionless communications such as a WWW, etc., a retrieval CGI stores a retrieval result in a file having a file name generated from a process ID and a user ID. Then, a retrieving/accounting process is performed in units of a user ID and a process ID. A session is managed using the process ID as information to be exchanged, thereby requiring no resident combinational software. Furthermore, a volume-dependent accounting can be realized even when communications are disconnected.