Lagoon, a WWW cache

There are two ways of providing local copies of hypertext nodes from different sites in a distributed hyperdocument: In order to use mirroring one needs an accurate way to predict which part of the distributed hyperdocument is most interesting to copy. For applications like a search algorithm, mirroring will not be very effective, as links to documents on different sites are favored by the fish-search for instance. Also, in order to keep a mirrored part of the hyperdocument up to date some cooperation of the originating site is needed to "send" new versions of nodes and links as they are created on that site.

Lagoon [BP94] is a cache for the World Wide Web, which operates independently from both the client (WWW-browser) and the server. Some browsers, including Netscape Navigator and Microsoft's Internet Explorer also offer caching. However, the disadvantage of such a "client cache" is that it is not shared between different users.

Currently the lagoon cache can be configured in two ways:

The most popular WWW-cache at this moment is Squid, a freely available cache which has its roots in the original WWW-server from CERN.