Scripting

Scripting is what makes Web pages actually do something instead of only showing something. The menu bars at the top of this Web site are good examples. They use scripting in a couple of ways: to build the menus from information in a database, and to change its appearance and behavior when you move the mouse over over it. The graphic to the left is a portion of the script that does that.

Most effective Web sites take advantage of both client-side and server-side scripting.

Client-side Scripting

Client-side scripting runs in the Web browser. It downloadsd with the rest of the page and becomes a program that runs within the browser. There are two scripting languages universally available: JavaScript and VBScript. JavaScript is the more concise of the two and the one we use be default, but VBScript is also available should you specify it.

Server-side Scripting

Server-side scripting runs on the server before the page downloads. More specifically, a server-side script actually creates the page on the fly, generally from information in a database. Amazon.com certainly does not have a separate page for each item in their inventory; there would be millions and maintenance would be impossible. No, they have a script that generates a page based on what their customers request. Search engines, ebay, and most online purchasing would be impossible without server-side scripting.

There are a number of technologies available, including Perl, PHP JSP and ASP. We will use PHP unless you specify otherwise or unless there is a good reason to use JSP or you require otherwise. As an additional note, ASP is only available on Microsoft Windows servers. Perl, PHP, and JSP are available anywhere.

Server-side Objects

Server-side objects are an option for complex Web applications such as ebay or a personnel management system. In cases such as these, it is difficult or impossible to design a reliable and efficient system using regular server-side scripting alone. Such applications are better suited to partitioning the business logic into appropriate objects, which are then invoked as required by pages that need them.

There are two commonly available environments for creating and using server-side objects. On Microsoft Windows-based servers, COM objects perform the business logic and accessed as necessary by Web pages. A more versatile and cross-platform approach, however, is to use Java-based objects in the form of servlets and Java Beans. There are systems available to facilitate the integration of these objects with Web pages, such as Struts and JavaServer Faces.

The ultimate in server-side object architecture is the Model-View-Controller paradigm.