How does a webserver interface with PHP

Question

I want to handle http requests via another webserver or own written server in future.

I want to understand how to provide php with request data properly.

• in what form request data should be provided
• how data is provided to php, via stdin or somehow else
• how php handles received request data afterwards, any additional actions required to fill $_SERVER variables etc.

Answer 1

It's pretty simple actually. The Webserver communicates with PHP through the CGI interface. This entails setting up environment variables, invoking the php interpreter, piping a POST body through stdin, and then reading the PHP response from stdout.

• Call PHP from virtual/custom "web server"
• How to pass POST data to the PHP-CGI?
• http://pear.php.net/package/HTTP_Server
• What is Common Gateway Interface (CGI)?

As to PHP postprocessing the $_SERVER variables: That's fairly minimal, it only constructs PHP_SELF and PHP_AUTH_USER etc. as documented in the manual. The rest is provided by the webserver (e.g. all HTTP headers converted into HTTP_* env variables).