WAIS and Gopher
Public WAIS is often used as a full text search engine for individual Internet Gopher servers, supplementing the popular Veronica system which only searches the menu titles of Gopher sites. WAIS and Gopher share the World Wide Web's client–server architecture and a certain amount of its functionality. The WAIS protocol is influenced largely by the z39.50 protocol designed for networking library catalogs. It allows a text-based search, and retrieval following a search. Gopher provides a free text search mechanism, but principally uses menus. A menu is a list of titles, from which the user may pick one. While gopher space is a web containing many loops, the menu system gives the user the impression of a tree.
The W3 data model is similar to the gopher model, except that menus are generalized to hypertext documents. In both cases, simple file servers generate the menus or hypertext directly from the file structure of a server. The W3 hypertext model gives the program more power to communicate the options available to the reader, as it can include headings and various forms of list structure.
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