New Technologies and What They Mean To You: Cold Fusion

By: Jeremy Wright
Published: 09th Oct 2002

Definition
A web application server that provides powerful scripting and databasing capabilities. ColdFusion was launched in 1995 by Allaire Corporation, and was the first web application server available for Windows NT. Amongst other things, it is able to interact with databases, track web page users, upload files to the web server, send email, and perform logical processing of data on the server.

ColdFusion is distinguished from other popular web application servers because its actions are programmed using a simple tag-based scripting language called ColdFusion Markup Language (CFML).

Macromedia purchased the Allaire Corporation in early 2001, and added ColdFusion to their line of server products. It is a prime candidate for even tighter integration with Macromedia's industry-leading development software (Dreamweaver, Flash etc), making it a smart choice for any web developer.

What It Really Is
According to the documentation, the ColdFusion product consists of four components:

• ColdFusion Server
• ColdFusion Markup Language
• ColdFusion Studio
• ColdFusion Administrator

The key parts of ColdFusion are really ColdFusion server and CFML.

CFML is a scripting language designed specifically for use by web developers. It is almost unique in that it is tag-based. This makes it easier for developers -- used to working in tag-based HTML -- to learn. Because it is specifically targeted at web development, it also encapsulates common web functions (such as connecting to a database) in single, easy to use CFML tags. The same functions might require several lines of code using a competing technology such as PHP or ASP.

CFML, as implemented in ColdFusion 5, includes over 75 tags and over 240 built­in functions. It also allows developers to extend the language by creating their own custom tags or user­defined functions (UDF), or by integrating COM, C++, and Java components.

The ease with which CFML can be learned, and the simple but effective code that can be written with it, are often cited as the killer reasons to use ColdFusion over competing technologies. In general, ColdFusion applications can be written in less time, and often by developers with less programming experience.

CFML code is written directly into pages on the web server, along with any HTML that may be required on that page. Each page, rather than being a normal web page, is now a ColdFusion page (or "ColdFusion Template" as Macromedia calls them). These pages are given a .cfm or .cfml file extension (rather than the typical .htm or .html extension for a normal HTML web page).

Advantages

• Simple to learn and use, fast application development time
• Cross-platform - currently supported on Solaris, Linux, Windows, HP-UX with code compatibility between platforms
• Comprehensive feature set - including built in graphing and charting functions, and Verity search engine
• Scales well to heavy loads
• Well supported by authoring tools
• Well documented

Disadvantages

• ColdFusion's core features are extensive, simple and effective. But extending its features can involve added complexity
• Costs more than competing platforms. A freeware version is available, but it is feature limited

Examples
The following code retrieves values from the tblMyTable.Word field in a database called myDataSource. It then outputs them all to a bulleted list on the same page.

Retrieve values from database, output as bullet list:

<!--- retrieve the records --
><cfquery name="myQuery" datasource="myDataSource" dbtype="ODBC">
SELECT Word
FROM tblMyTable
ORDER BY Word
</cfquery>

<!--- output the records ---><ul>
<cfoutput query="myQuery">
<li>#myQuery.Word#</li>
</cfoutput>
</ul>

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