Inner workings of PHP

I was wondering if there's a decent resource for finding the inner workings of PHP.

I have taken a look at the source, but a decent explanation would really help.

Some example questions I'd like answered.

How does a PHP script get interp开发者_如何学运维reted into machine readable code?

How does it interact with Apache, how does apache collect the HTML response from PHP?

And other questions like that.

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It may be a bit outdated but I think you'll find this useful:

PHP internals and the Zend API

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Have you taken a look at this thread on Reddit:

IAm finishing my PhD in compilers. I wrote a PHP compiler. AMA

http://www.reddit.com/r/IAmA/comments/9rpa3/for_my_fellow_geeks_iam_finishing_my_phd_in/

including the related Google Tech Talk.

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The best book on te topic is Sara Golemon's Extending and Embedding PHP.

It uses PHP 5.1.0, but everything should be appliable to any 5.x. You can find information about changes to 5.3 (especially for namespaces) in the source code.

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The PHP website is http://php.net/. It has a lot of information.