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* DB/C Newsletter *
* January 1997 *
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Editor's Notes
Beta testing of both FSS 1.0 and DB/C 9.1 is progressing well. The
release of both products should happen by the end of January. Check the
DB/C WWW page later in January for details (www.swc.com/dbc.html).
In addition to offering the DB/C classes in Oak Brook, we are probably
going to offer the same classes electronically on CD-ROM or video tape. If
you have any suggestions about what we should include in the classes or in
what form these should be produced, I would like to hear from you. We expect
the first of these to be available by April 1997.
If you don't already have the DB/C Newsletter delivered to your email
address and would like to have it emailed to you once a month, just send an
email message to 'majordomo@swc.com' and put the line 'subscribe dbcnews' in
the body of the email message (omit the ' characters). The newsletter will
be delivered to the email address from which the message was sent.
Several people have asked if it is possible to write WWW interface
programs in DB/C. The answer is yes and this month's article describes how
to do it. If you put a DB/C WWW interface into production, let me know.
We would like to share such interesting success stories with the readers of
this newsletter.
don.wills@swc.com
DB/C and CGI
The WWW is now mainstream. Wherever you look today in newspapers, in
television advertising, and in many other surprising places, you will find
WWW page addresses. The purpose of these WWW pages may be advertising,
information, commerce or fun. Whatever the purpose, they are everywhere.
Many of these WWW pages are becoming more than just passive advertising
or information pages - they are interactive. These interactive pages usually
have one or more fields that need to be filled out, and then you press a
submit or OK button to send the data to the WWW server. The server then
responds with a data screen or an appropriate response. This interaction
is similar to traditional data entry processing.
The Common Gateway Interface (CGI) is the most widely used standard for
processing the information that is submitted from interactive WWW pages.
It is a fairly simple standard that was originally designed for UNIX, but
has been adapted to other WWW server operating systems. Detailed information
about the CGI standard can be found at:
http://www.w3.org/pub/WWW/CGI/Overview.html
A good introductory book about CGI is 'CGI Programming in C & Perl' by
Thomas Boutell (Addison Wesley). In this article, we won't go into all of
the details of CGI, but we will provide enough information to get you started
using DB/C with CGI.
To illustrate DB/C and CGI, we will use a simple example that tests to
see if a number is prime. This user inputs a number that is sent to the WWW
server. The WWW server responds by telling the user whether that number is
prime or not. If you want to see this example running, goto this WWW page:
http://www.swc.com/prime.html
Just fill in the field with a number and click on the Test button.
The Hyper Text Markup Language (HTML) is the special language that is
used to specify the format of a WWW page. HTML is the output of the various
WWW authoring tools like Microsoft Frontpage. By using a tool like Frontpage,
you don't actually need to learn HTML. You can also create a WWW page
directly with a text editor by just embedding the HTML tags. Here is the
complete 'prime.html' file used in our example:
Prime Number Tester
Each HTML tag is inside the < > characters. Many HTML tags have a scope
of action. The / means end of scope or end of section. The
tag means
line break. This tag: