13.2.1. Server-Side Includes

13.2.2. PHP

Another approach to the problem of orchestrating HTML with CGI scripts, databases, and Apache is PHP. Someone who is completely new to programming of any sort might do best to start with PHP, which extends HTML — and one has to learn HTML anyway.

Instead of writing CGI scripts in a language like Perl or Java, which then run in interaction with Apache and generate HTML pages to be sent to the client, PHP's strategy is to embed itself into the HTML. The author then writes HTML with embedded commands, which are interpreted by the PHP package as the page is served up. For instance, you could include the line:

Hello world!<BR>

in your HTML. Or, you could have the PHP statement:

<?php print "Hello world!<BR>";?>

which would produce exactly the same effect. The <? php ...?> construction embeds PHP commands within standard HTML. PHP has resources to interact with databases and do most things that other scripting languages do.

The syntax of PHP is based on that of C with bits of Perl. The main problem with learning a new programming language is unlearning irrelevant bits of the ones you already know. So if you have no programming experience to confuse you, PHP may be as good a place to start as any. Its promoters claim that over a million web sites use it, so you will not be the first.

13.2.3. Perl

Perl, on the other hand, is an effective but annoyingly idiosyncratic language that has not been designed along sound theoretical lines. However, it has been around since 1987, has had many tiresome features ironed out of it, and has accumulated an enormous body of enthusiasts and supporting software in the CPAN archive. Its star feature is its regular expression tool for parsing lines of text. When one is programming for the Web, this is constantly in use to dissect URLs and strip meaning out of the returns from HTML forms. Perl also has a construct called an "associative array," which gives names to the array elements. This can be very useful, but its syntax can also be very complicated and mind-bending.

Perhaps the most serious defect of Perl is its absence of variable declaration. You can make up variable names on the fly (usually by mistyping or misthinking): Perl will create them and reference them, even if they are wrong and should not exist. This problem can be mitigated, however, with the use of the -w command line flag, as well as the following:

use strict;

within the scripts.

13.2.4. Java

As we went to press with this edition, it became plain that this Luddite view might have other supporters. Velocity, seemingly yet another page-authoring language, but one written in Java so that you can mess with its innards, was announced:

Velocity is a Java-based template engine. It permits web page designers to use simple yet powerful template language to reference objects defined in Java code. Web designers can work in parallel with Java programmers to develop web sites according to the Model-View-Controller (MVC) model, meaning that web page designers can focus solely on creating a site that looks good, and programmers can focus solely on writing top-notch code. Velocity separates Java code from the web pages, making the web site more maintainable over the long run and providing a viable alternative to Java Server Pages (JSPs) or PHP.

13.2.5. Other Options

Python is fairly similar to Perl — less well known but also less idiosyncratic. It is also a scripting language, but one that has been properly written along sound academic lines (not necessarily a bad thing) and is easy to learn.