WAIS (Wide-Area Information Service)
WAIS is a collection of programs that implements a specific protocol (Z39.50) for information retrieval, and can index large distributed collections of data around the Internet. WAIS uses database technology to provide content-oriented query services to WAIS clients, and is one of the more powerful Internet search tools available. Unlike the other things we've called search engines here, WAIS is able to search a multitude of data resources in real time without relying on the collection efforts of robots to build databases.
WAIS (pronounced "ways") is an Internet service, a network of publishing systems designed to distribute all kinds of data to a variety of clients. The core WAIS engine is simple to install, easy to use, and when pointed at relevant data compiles indexes for easy assimilation to provide access through the WAIS service.
WAIS originated as a large distributed database of interconnected content servers located on regional and international networks. The original framework is still supported by current version, but each content server is also capable of answering queries from its own local data store. Although a user might cause a large number (even into the thousands) of back-end WAIS engines to respond to a single query, this is the exception rather than rule, because many WAIS servers are configured to only access their own local databases.
WAIS was developed as a joint project that brought together the following companies: Thinking Machines, Apple Computer, Dow Jones, and the KPMG Peat Marwick group. The "free" version of WAIS that you'll commonly find on the Internet still bears a strong resemblance to the original version. This version gives you access to the server's source code, the engine that indexes the data, and a number of utilities to manage the resulting information pool.
However, Thinking Machines no longer supports the publicly distributed WAIS (as of version WAIS-8-b5.1). Support and development of the free version now belongs to the Clearinghouse for Networked Information Discovery and Retrieval (CNIDR). Current CNIDR releases, called freeWAIS, are available from many of the popular Internet software archives (visit the CNIDR URLs mentioned earlier for more information).
The commercial side of WAIS research and development is now in the hands of WAIS, Incorporated, a company founded by most of WAIS's original primary developers. Although WAIS, Inc., sells fully-supported commercial servers chock-full of additional features, they continue to provide other free tools (visit the WAIS, Inc. URL mentioned earlier for more information about the company and its products).
As we mentioned earlier, WAIS allows indexing and retrieval of a large number of different data types. Client applications can search on and retrieve information about nontextual information resources, according to predefined translation standards. Many of the popular WAIS clients on the market today support most of the elements mentioned in the table below, and other programmers are continually developing new translations to add more kinds of data to those WAIS can index and search. This means that WAIS can search on and provide information from files stored in all of these formats (below) with equal dispatch and facility.
WAIS operates as another of the many Internet services as a client/server application. What this means is that the WAIS system is inherently efficient, scalable, and capable of supporting different kinds of clients (any that can run a WAIS client application, in fact). A Macintosh WAIS client, native to the Macintosh OS, retains its ability to converse with the server using a rigidly defined WAIS protocol called Z39.50. This common method of information exchange is what makes WAIS both portable and scalable.
If you compare this to a proprietary cataloging scheme that requires its users to employ or emulate a particular kind of terminal (such as a VT100), as well as forcing them to interact with the host system using its own peculiar interface and commands, WAIS looks pretty good. The WAIS server exchanges question and answer information with a whole range of client types, with each using its own native interface, and all are connected by a shared protocol. WAIS doesn't care what kind of platform it's talking to, nor does it care what happens to the data it delivers to the client, other than ensuring successful delivery of the results. Several interesting interfaces between WAIS and the Web are available (check the URLs in the preceding section for pointers, or refer to Chapter 19 "Using WAIS with CGIs" in Foundations of World Wide Web Programming, with HTML and CGI by Ed Tittel, Mark Gaither, Sebastian Hassinger, and Mike Erwin, IDG Books Worldwide, Indianapolis, IN, 1995, ISBN 1-56884-703-3).