How Did PHP Develop?

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If you like to know how a technology has developed, this section is for you. Here I cover how PHP has developed historically.

PHP 1.0

The story of how PHP was developed begins in 1994 with Rasmus Lerdorf. At the time, Lerdorf had just graduated from college and wanted to track the number of users visiting his online resume. He created Personal Home Page tools for this task, which were effectively a bunch of CGI scripts written in Perl.

PHP 2.0/FI

Lerdorf's friends were interested in these scripts, and at their request, he started adding more features. He decided to redevelop his PHP tools in C, and he added some programming features and an HTML Form Interpreter. This became known as PHP 2.0/FI and was a kind of semi-programming language that could be added to standard HTML code.

At this point, PHP 2.0/FI became open source (this topic is covered more in a moment), and a group of developers (Lerdorf, Andi Gutmans, Zeev Suraski, Stig Bakken, Shane Caraveo, and Jim Winstead ”also covered more in a moment) gathered around PHP to create PHP 3.0.

PHP 3.0

While PHP 2.0/FI was still around, two university graduates, Andi Gutmans and Zeev Suraski, were using PHP for a university project and had created a new, much improved core scripting engine for PHP. Encouraged by their professor , Michael Rodeh, who also was head of IBM research in Haifa, Israel, they released the source code for the new engine to the PHP community. The community built on the new engine, and it quickly became the official next release of PHP ”PHP 3.0.

With PHP 3.0, the Form Interpreter was added to the PHP core, and the programming language was built upon. What developed from PHP 2.0/FI was one of the first web programming languages of its kind ”a server-side programming language mixed with HTML. Up to this point, most web-based applications had been built using CGI and Perl or C++. Along with ColdFusion and ASP, PHP helped introduce a new way to mix HTML and a programming language on the same page.

Even at that point, PHP was a powerful programming language. As an open-source language, it was growing in its functionality and features.

PHP was refined, and although it was based on C and C++, it also took features from languages such as Pascal, Basic, and Perl. PHP 3.0 also added an API so that developers could write PHP modules and further extend PHP without needing to change and compile the PHP core.

Gutmans and Suraski were looking to the future. They put the PHP core through another rewrite to help create PHP 4.0.

PHP 4.0

Of all the versions, PHP 4.0 is the most powerful and modular. It quickly helped PHP prove itself as an enterprise-wide contender comparable in might to ColdFusion and ASP.

PHP 4.0 is the most powerful version of PHP to date. Significant changes to PHP helped it grow past its roots as a collection of Perl CGI scripts to a full-fledged web programming language. PHP scripts are no longer run line by line; instead, they are compiled and then run. Object-oriented support was implemented, and important new types and strict type checking and matching features were added.

Suraski and Gutmans created the Zend Corporation. Half of the PHP core was under commercial license (called the Zend engine). Much of the PHP core and the PHP language itself remain open source. With the rewrite, PHP was even more modular than before.

As you will see later in this chapter, Zend has created many products that can be added to the PHP core to increase power and flexibility.

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