PFTPD: an FTP proxy system to assure the freshness of files

As more software is being developed and distributed via the Internet, the number of accesses to file servers, such as FTP servers or WWW servers, is increasing. To reduce concentrated access to the original file server, mirror servers which have the same directories and files as the original server stores have been introduced. However, inconsistency among mirror servers and the original server is often observed because of transfer latency, traffic congestion on the network, and management policy of the mirror servers. Hence, we develop an intermediate FTP proxy server system PFTPD (Proxy FTP Daemon) which guarantees the freshness of files as well as dispersal of the access concentrated on the original FTP server. We found that the proposed system can disperse accesses to the mirror servers with a little overhead. This technology can assure that files are the latest version and adapt to heterogeneous network environments such as the Internet.