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Proxy and caching servers

The CERN server is a caching proxy server. A proxy is a program that acts as an agent for its clients, making requests on their behalf (in the case of a Web proxy server, the clients are browsers, other Web servers and client programs). Proxies are useful where the browser programs cannot access remote servers, typically in the situation where an organization forbids direct connections between internal machines and outside machines. The proxy can be run on a firewall machine, which is a system that is connected both to a local network and to a public network, and can communicate with machines on both networks. Machines on the local network are said to be inside the firewall. Browsers may be set up to channel all requests through a proxy server. Web proxies are described in a paper by Ari Luotonen and Kevin Altis[14].

The usefulness of the CERN server as a proxy is enhanced by its ability to cache the files it retrieves. Subsequent requests for the same files may be satisfied from the cache rather than the remote server, thus avoiding traffic on the external network. The internal network often has a much higher bandwidth than the external network so requests satisfied from the proxy's cache will be delivered faster than those retrieved directly. Retrievals of documents from remote servers can be disabled. This feature can be useful for demonstrations, where connection to an external network would be impracticable.

Spinning the Web by Andrew Ford
© 1995 International Thomson Publishing
© 2002 Andrew Ford and Ford & Mason Ltd
Note: this HTML document was generated in December 1994 directly from the LaTeX source files using LaTeX2HTML. It was formatted into our standard page layout using the Template Toolkit. The document is mainly of historical interest as obviously many of the sites mentioned have long since disappeared.