ED-MEDIA 1999 Proceedings Book - Association for the ...

DATABASE-DRIVEN WEB APPLICATIONS FOR TEACHING & LEARNING
1. Introduction
Daniel Y. Lee
Department of Economics & Coordinator, the Virtual University
Shippensburg University
Shippensburg, PA 17257 USA
DYL@ship.edu
Although many instructors now utilize the Web to supplement their courses, the Web pages they create are
mostly “static” in nature. These HTML documents are written and then posted onto the Web server, where they sit until
requested by a browser. Materials on these documents are outdated overtime until the Web developer revises them one
page at a time, which requires considerable time and effort, especially as Web pages multiply. In the long run, a better
strategy to maintain a Web site is to use “dynamic” pages linked to databases. These Web pages are "dynamic" in the
sense that they are created “on the fly.” They don’t exist until a browser makes the request. Upon the information user’s
request, the database inserts the requested information into preformatted HTML templates. If the information in the
database is updated, the Web page will display the new information the next time it is requested by the user. The purpose
of this paper is to provide an overview of how educational Web sites can be more easily administered, modified, and
customized by using Web-database connectivity.
2. Developing Database-Driven Web
2.1 Advantages of using database-driven Web
Web browsers provide a Graphical User Interface (GUI) that can be used to access many things, including a
database. Unlike the traditional database management systems, the user would not have to configure and learn to program
database client software. Instead, using a Web browser's built-in forms capability, users can access a database by simply
filling in the data they want and pressing a button. The returned data can then be presented in an easily readable format.
Furthermore, the Web's cross-platform support allows users on many different types of computers or platforms (Windows,
Mac, Unix) to access a database from anywhere in the world. Information can be disseminated with a minimum of time
and effort, without having to solve compatibility problems (Lee and Liu, 1998).
There are several advantages of using database-driven Web development over the conventional “static”
Web pages. First of all, Web pages can be created “on the fly” by querying current information stored in the
database. New and fresh information can be presented to the user at each visit. This technology also makes it easier
to administer, modify, update, and customize a Web site. In addition, users can tap into vast existing databases
including many legacy systems through Web-database interaction. This allows for cross platform access without
requiring custom client applications. Furthermore, database-driven Web makes it possible such useful functions as
maintaining user state, i.e., user’s preferences and other user-specific information can be stored between visits for
various uses. In addition to these benefits, database-driven Web renders particular advantages to educational Web
sites. Databases are “an excellent way to manage the media components of a Web site … instructional Web sites
comprise huge numbers of media objects and multiple of content creators; databases make managing this
information and longer-term maintenance issues easier to address” (Ashenfelter 1998).
2.2 Mechanism of database-driven Web
Typically, the Web server delivers a block of text written in the HTML to the browser, which parses the HTML
and may request additional content, such as graphical data. The model works well for static data, but what about live data
For example, how would a Web server deliver content that it generates based on user input One answer is to use a CGI
(Common Gateway Interface) script to handle the database queries. CGI scripts are programs that let Web servers
execute other programs and incorporate their output into HTML documents. The Web server executes a CGI
program as a separate process to fulfill a user's request, which can be as simple as a Web page hit counter or as complex as
a database query. Because a CGI program is external to the Web server, it can be written in virtually any language,