By Jennifer Kyrnin

When is the last time that you wished you could add in a copyright notice to every one of your pages at once? Or perhaps you want to make sure that all your pages have the same header and footer on them. Last week, I spoke about how to use databases to create dynamic content, and they can also be used to create standard content across your pages. But there is one drawback to most of those systems. They are expensive.

Enter the HTML Pre-processor. The HTML pre-processor is an application that runs on your server and filters the HTML before it is sent to the browser. They work in many different ways, but for the Web developer they become invaluable in creating dynamic pages with common elements.

Most pre-processors are run when you have created your data files. You can then update your Web pages by running the processor to convert the data files to HTML. The HyperText Database mentioned last week worked in this fashion. But some pre-processors work on the fly as the Web pages are accessed, ColdFusion is a good example of this.

But there are many more pre-processors out there, many of which are freeware and fairly easy to set up and use.

• PHP: Hypertext Processor
  This is one of the better known open source HTML pre-processors available. However it acts more than just a preprocessor, it is more like an HTML scripting tool to include logic in your HTML and other programming functions. PHP runs on the Web server. It comes in a Windows binary distribution and source code to compile on other platforms. Open source freeware.



• GTML
  GTML allows you to group your Web pages into projects for instant search and replace capabilities across the whole project. You can easily create macros for sections of your site that are reused and then simply put in the one word representation of that code, GTML builds the HTML for you. GTML is a Perl script, but will run on any platform that supports Perl. Open source freeware.



• htmlpp - The HTML Preprocessor
  This HTML pre-processor has many of the same features as listed above, but one really interesting aspect is that you can embed Perl code and include the output on your HTML pages. It also can query flat file databases. GNU open source freeware.



• HPP
  HPP, while still under development, is an interesting looking Perl script that will process directives sent to it via GET requests within Web pages. For example, you would write your HPP enabled Web page, and then access it on the command line of the browser: cgi-bin/hpp?index.html It gives you a lot of freedom to include the results of Perl scripts in your Web pages dynamically. Alpha-level open source freeware.

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