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Web Programming

Common Gateway Interface

CGI acts as a bridge between the browser and the server, has been around since the first days of the Web, and is the most consistent of all programming methods.

It's not a programming language per se, but is a standard or a set of protocols that allows programs and Web pages to interact with a server. Information can be entered from the browser (what your viewer is seeing), sent as an HTML-based inquiry to your server (where your site resides), be instructed by the CGI to process the information, and deliver the results back to the browser (either to the end-user, or via email to you.)

The most common uses of CGI and cgi-scripts (usually written in Perl or C and are what interprets the information for the server) are for forms, shopping carts, and searches. These are server-side includes. Other applications include database storage and retrieval (currently being replaced by more advanced database servers like Cold Fusion), logging information, guestbooks, feedback forms, and randomization processes. See The CGI Resource Index for more information.

Active Server Pages

ASP is Microsoft's server-sided processing function, and acts similarly to CGI. It is a component installed on your server to help exchange information from the browser to the server. It requires NT Server, NT Workstation, or other Microsoft os servers to run, but it can be delivered to any browser or platform. Therefore, it is cross-platform and cross-browser compliant.

The default language for ASP is VBScript or Visual Basic Script, Jscript (Microsoft's version of JavaScript), or Perl, but other languages that build on the server side will work. See An ASP You Can Grasp: The ABCs of Active Server Pages for more information.

JAVA

Java is a very powerful scripting language modeled after C++. This code is versatile enough that an entire program can be written that doesn't require a browser at all, and can run stand-alone. An example of this is an applet (similar to animated GIFs).

Java can be run across multiple platforms and operating systems, but because of the in-fighting of the "Java Wars" between Sun and Microsoft, there have been complaints about the technology.

Java is a client-side script. It can use the browser's internal Java machine to access built-in Java functions instead of embedding the function onto the page. See Sun on the Java technology.

JavaScript

Sun, working with Netscape, took a developing script called LiveScript and made it more like Java, to run client-sided. It is part of the code written into an HTML page, so runs right in the Web page itself. It carries out a number of client-sided functions, and I am always asking students for new bits of JavaScript code to add to my collection. It is well worth your while to learn at least the basics of JavaScript if you want to write better Web pages.

JavaScript does have its browser issues (for instance JavaScript 1.2 is not supported within IE 4.0) and your use must be degradeable. Design with your viewer in mind, and use only as it adds to your site, not just because you can do it. And make sure the piece of script is written by a competent programmer - you don't want to crash someone's system! Microsoft has a similar script called JScript, and both programming languages use a complex syntax like C/C++.

Check out The JavaScript Source for scripts you might use.

VBScript

Visual Basic is a programming language developed by Microsoft. It's more intuitive to use than JavaScript, and doesn't have the case sensitivity that makes JavaScript more cumbersome to write. It is the default language of ASP so is a great server-sided script language for any servers running ASP. Because of its intuitive code and excellent security, it was once referred as the "Java Killer".

However, it too is victim of the browser wars and can only be used on IE v3.0 and higher. It is not supported in any Netscape browser. Here's a VBScript tutorial you might enjoy: http://www.intranetjournal.com/corner/wrox/progref/vbt/index.html

DHTML

Dynamic HTML extended HTML to overcome some of the limitations in designing using strict HTML code. However, the way the two major browsers choose to implement DHTML code differs and causes problems in its use, even though it has been reviewed and recommended for use by the World Wide Web Consortium (W3C).

• Internet Explorer
  • version 4.0 or higher
  • uses any tag on a page to accept a DHTML script
  • you can dynamically alter the layout and content of your page without going back to the server
  • all code can reside within the one page
• Netscape 4.0
  • Netscape is less consistent than IE in implementing DHTML.
  • It's lack of versitility is due to a lack of the Document Object Model (DOM) found in IE. The script can't access the object (tag), but instead uses layers to achieve similar effect.

The idea behind DHTML is to allow script functions into every available HTML tag. This is what conceptually moves HTML from a formatting script to an actual programming-style language. Client-sided programming like this gives all Web designers greater functionality and design possibilities.

Try this tutorial from Macromedia: Animating layers in a timeline

ActiveX

ActiveX is not a programming language, but a hybrid of object-oriented programming that allows complete programs to run inline. It needs a language like VBScript to render within a browser.

XML

This is Extensible Markup Language, a subset of SGML. It is another method to markup documents. Verdict is still out on how far it will be accepted by the design community. Acceptance by browser developers and the W3C will determine its fate.

Webcasting

Simply said, you send the information directly to the viewer without input from the viewer.

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