Prior to working through the rest of this chapter, you should retrieve
clean, unmodified source trees of your favorite Web server. We're working with
Apache (available at
and, of course, with PHP (available at
http://www.php.net/ - does
it need to be said?).
Make sure that you can compile a working PHP environment by
yourself! We won't go into this issue here, however, as you should
already have this most basic ability when studying this chapter.
Before we start discussing code issues, you should familiarize
yourself with the source tree to be able to quickly navigate
through PHP's files. This is a must-have ability to implement and
The following table describes the contents of the major directories.
Main PHP source files and main header files; here you'll find
all of PHP's API definitions, macros, etc. (important).
Everything else is below this directory.
Repository for dynamic and built-in modules; by default, these
are the "official" PHP modules that have been integrated into
the main source tree. From PHP 4.0, it's possible to compile
these standard extensions as dynamic loadable modules (at
least, those that support it).
This directory contains the main php macros and definitions. (important)
Directory for the PHP Extension and Application Repository. This directory contains
core PEAR files.
Contains the code for the different server abstraction layers.
Location of the "Thread Safe Resource Manager" (TSRM) for Zend
Location of the Zend Engine files; here you'll
find all of Zend's API definitions, macros, etc. (important).
Discussing all the files included in the PHP package is beyond the
scope of this chapter. However, you should take a close look at the
php4/main/php.h, located in the main PHP directory.
This file contains most of PHP's macro and API definitions.
php4/Zend/zend.h, located in the main Zend directory.
This file contains most of Zend's macros and definitions.
php4/Zend/zend_API.h, also located in the Zend
directory, which defines Zend's API.
You should also follow some sub-inclusions from
these files; for example, the ones relating to the Zend executor,
the PHP initialization file support, and such. After reading these
files, take the time to navigate around the package a little to see
the interdependencies of all files and modules - how they relate to
each other and especially how they make use of each other. This
also helps you to adapt to the coding style in which PHP is
authored. To extend PHP, you should quickly adapt to this style.
Zend is built using certain conventions; to avoid breaking its
standards, you should follow the rules described in the following