Electronic search and display tools.

It often has been said that the Internet is starting to provide the largest library humankind has ever had. As true as this may be, it is also the messiest library that ever has existed. Navigation and display tools such as Mosaic allow users to browse the World Wide Web and display text and multimedia objects. Search tools such as the Wide Area Information Server (WAIS) and Archie and Veronica allow people to search specific directories or list archives (see [22] for an overview of tools). However, in addition to index and directory services or navigation tools, it has become apparent that such 'a posteriori' tools to organize the unstructured Internet universe are not sufficient. Rather, some 'a priori' structuring is necessary. This was first done quite successfully with Gopher [3] and later with WWW [5]. However, "first generation hypermedia techniques" do not seem to be sufficient for large amounts of data: "second generation techniques" [4] involving distributed database mechanisms, scope definition facilities for searches, bidirectional link databases [14] for automatic link maintenance, and other advanced techniques are emerging. For example, Harmony [11], the X-Windows client for Hyper-G, WWW, Gopher and WAIS provides sophisticated navigational facilities when used in conjunction with a Hyper-G database: the facilities include visual "local maps" of all in- and outgoing hyperlinks, a 3-D landscape generator, a history and hierarchy browser, Boolean searches on attributes, full text searches including approximate matches in user-defined scopes that may arbitrarily cross even the physical boundaries of servers. Such features will make working with large electronic libraries less frustrating than it is sometimes now, and will certainly assure that the use of electronic libraries is more efficient than using large amounts of printed material. As these tools evolve, better integration of search and display will be necessary. One approach is dynamic queries [2] that provide graphical representations for database elements and sliders for adjusting parameters on those elements. As parameters are changed, the graphical display is immediately updated, providing immediate visual answer sets.