With the advent of Web database technology, Web pages are no longer static, but dynamic with connection to a back-end database. Web sites are now able to display updated information on-the-fly and support user interactivity. What's more, one can use the same page to display information of thousands of products in a database. Data-driven pages take the emphasis off managing the site itself and allows a business to focus on the content.

Here we will have a brief overview of the Web database connectivity, and focus on the middleware of the Web database.

Trinity -- Three tiers of Web Database:

To build a Web database, usually we need use a three-tier model: Web server, Web application server (middleware), and database. The trinity is best illustrated by the figure below (source):

How a user interacts with a Web database:

The interface between the system and a Web user is a Web browser.

1. In a Web browser, a user submits a request to the Web server.
2. The Web server passes it onto the middleware
3. The middleware writes the request in SQL queries and sends it to a back-end database.
4. The data retrieved are handed back to the middleware
5. The middleware generates a Web page for the data
6. The Web server sends the Web page to the browser
7. The browser displays the Web page in front of the user

A simplified flow chart is shown below (source):

Middleware explained

We hurry to add that Web-database connectivity takes several different forms, such as:

• CGI scripting A custom application is developed using a traditional programming language (such as C++, Python, Perl, or Java) accessed through the Common Gateway Interface (CGI).
• Application server Such as ColdFusion or ASP, which works with the Web server through its Application Programming Interface (API) to act as an extension to the Web server that can communicate with databases through ODBC or other interfaces.
• Integrated application server Such as File Maker Pro which offers its built-in Web server, or Oracle9i Application Server which integrates with Oracle database to build an Internet Platform.

Here we use the notion of Web-Database middleware in its broadest sense -- software that communicates between Web server and database.

The four types of middleware we discuss here -- PHP, ColdFusion, Active Server Page (ASP), and JavaServer Page (JSP) -- all feature tag-based server-side scripting. We choose these four because of their popularity, flexibility, compatibility, and potentiality. In our discussion, we will focus on their interaction with Web server and database. Besides introducing some basic syntax and showing some sample codes. we will also compare their features.

Links (with ratings)

Web Databases @ Web Developer's Virtual Library (*****)

Columns by John Paul Ashenfelter @ Webreview (*****)

Useful Links for Web-Database connectivity @ Netscape (****)

Choosing a Web database @ builder.com (***)

An annotated list of middleware tools @ Netscape (**)

Presentation outline on Web Database @ SILS (**)

[Back to top]