HTML 4.0 Sourcebook
(Publisher: John Wiley & Sons, Inc.)
Author(s): Ian S. Graham
ISBN: 0471257249
Publication Date: 04/01/98

However, there are also several shareware and freeware programs that are not bound to a particular server platform and that provide similar server scripting functions. Some of the more popular packages are:

These tools are much more sophisticated than server-side includes and support parsed documents that are essentially programs, complete with branching and conditional execution. The corresponding document markup often resembles HTML, but with additional, special-purpose tags reflecting the “language” of the preprocessor. Most of these packages support database access commands, allowing for dynamic document generation based on server database content.

CGI Utility Programs

CGI Program Resource Sites

http://www.cgi-resources.com/

www.oac.uci.edu/indiv/ehood/perlWWW/

www.yahoo.com/Computers_and_Internet/Internet/World_Wide_Web/CGI_ _ _Common_Gateway_Interface/

This section lists several commonly useful CGI gateway programs and utilities, such as mail forwarders or feedback form/guestbook utilities, document access counters, and UNIX man (manual) page-to-HTML converters. Of course, this is an incomplete list, and you should search the Web if you need a tool that is not listed here—the URLs at the start of this section provide some useful starting points. You should also look in many of the Web magazines currently in print, as many commercial CGI packages are advertised in such venues.

Email Handler

www.boutell.com/email/

This package, due to Thomas Boutell, is a simple C-language CGI program that lets browser users send e-mail messages to a restricted set of allowed recipients. This package is quite simple and has been used as a model for several other, more extensive, implementations.

Server-Side Include Page Counters

www.yahoo.com/Computers_and_Internet/Internet/World_Wide_Web/Programming/Access_Counts/

There are many CGI programs that, via the server-side include mechanism, can count the number of times a page is accessed. This URL references the page at Yahoo! where many of these CGI programs are listed.

CGI Database Gateways

Many Web applications are now designed as front-ends to sophisticated database systems. This requires gateway programs to take the FORM or ISINDEX -based query data and communicate them to the back-end SQL (or other) mechanisms used by databases such as Sybase, Oracle, and WAIS. The following is a very brief list of some such Web-database gateway tools, along with some hints as to where to find additional information.

If you are using a commercial database product, either on UNIX, Macintosh, or Windows platforms, then you should contact your vendor to obtain whatever Web interface software they provide. All database vendors now provide sophisticated gateway and server plug-in modules that connect their products to Web-based query interfaces. The following section is more likely to be of interest to those using freeware or shareware databases such as freeWAIS, mSQL, or postgres.

WAIS Gateways

WAIS, for Wide Area Information Servers, is an extremely popular text-database system. WAIS was designed as a client-server system, enabling WAIS clients to interrogate WAIS databases using a well-defined protocol and URL scheme. It is particularly popular because it is free—the freeWAIS software is a simple, yet powerful, text indexing tool and is often a good option when cost is a factor or when commercial software is not available or appropriate. This protocol is supported by some Web clients, so that it is often possible to directly interrogate a WAIS server by constructing a URL (with appropriate query strings) that points to that WAIS server.

However, most browsers do not support wais URLs. Furthermore, most users wish (and need) to design database queries using fill-in forms, so there is a need for software that can take the form data, convert it into an appropriate WAIS query, forward the query to the database, and then return the database results to the user. Indeed, there are now many gateway programs that support such interfaces to WAIS servers. The following section lists some of these packages.

KidofWAIS

www.cso.uiuc.edu/grady.html

Kidofwais.pl, by Michael Grady, is a perl script WAIS gateway program. Kidofwais.pl uses the simple ISINDEX query interface, but allows for pattern searches (astro* matches any word beginning with “astro”) as well as complex Boolean searches. The program returns search results complete with useful information about the resulting items, such as document type and length. In addition, when the documents are retrieved, the search string is highlighted in boldface for easier location and identification.

SFgate

ls6-www.informatik.uni-dortmund.de/SFgate/SFgate.html

Sfgate, by Norbert Gšvert and Ulrich Pfeifer, is another perl-based WAIS gateway program but is distinctly different from wais.pl or its derivatives. SFgate does not access a server-side WAIS query engine. Instead, WAIS client software is built into SFgate, so that it can itself query any Internet-accessible WAIS database. In addition, SFgate supports a form-based query interface, so that the user can select various databases (which can be searched at the same time) and enter complex query information into text input boxes. You can also create customized form interfaces to make it easier for users to access the database.

Although SFgate can work with any freeWAIS server, it is designed to work best with freeWAIS-sf. FreeWAIS-sf is a WAIS variant, modified, among other things, to allow for structured fields. Information about freeWAIS-sf is found at:

http://ls6-www.informatik.uni-dortmund.de/freeWAIS-sf/

ftp://ftp.germany.eu.net/pub/infosystems/wais/Unido-LS6/freeWAIS-sf/