Web Server Independence

PHP 4 interaction with the server, through a standard SAPI abstraction layer.
PHP-4 works as a native module not only from within Apache, but also as a native ISAPI extension of IIS, Zeus and AOL Server (NAPI).
Thread-safety is provided, allowing a multi-threaded process to perform numerous tasks concurrently, independently of the Web Server .

PHP 4 interaction with the server, through a standard SAPI abstraction layer.