Platforms, Servers, Databases, and PHP

PHP is truly cross-platform. It runs on the Windows operating system; most versions of Unix, including Linux; and Macintosh OS X. Support is provided for a range of Web servers including Apache (itself open-source and cross-platform), Microsoft Internet Information Server, WebSite Pro, the iPlanet Web Server, and Microsoft's Personal Web Server. The latter is useful if you want to test your scripts offline on a Windows machine, although Apache can also be run on Windows.

On most servers PHP can be installed as a server module. In other words, it runs as part of the server process rather than as a separate application. PHP is also installed as a standalone command-line application.

In this book, we will concentrate on building Web applications, but do not underestimate the power of PHP as a general scripting tool comparable to Perl. The fact that PHP runs as a command-line application means that any server that supports CGI scripts should be able to work with it. Configuration, though, will vary from server to server.

PHP is designed to integrate easily with databases. This feature is one of the factors that makes the language such a good choice for building sophisticated Web applications. PHP supports almost every database currently available, either directly or via Open Database Connectivity (ODBC).

Throughout this book, we will use a combination of Linux, Apache, and MySQL. We will also introduce SQLite, a lightweight but powerful SQL library that is newly bundled with PHP 5. All these are free to download and use and can be installed relatively easily on a PC.