On the Clancats.com blog there's a recent post showing how to create a web server in pure PHP, an interesting experiment but definitely not recommended for any kind of higher load situation.

Well, this is pretty useless, but it is possible. But again its pretty.. uesless. This tutorial will hopefully help you to better understand how a simple webserver could work and that it's no problem writing one in PHP. But again using this in production would be trying to eat a soup with a fork. So just, .... just don't. Let me shortly explain why this is not a that good idea.

PHP is a scripting language that simply is not really designed for such tasks. A webserver is a long running process which PHP is not made for. Also PHP does not natively support threading ( pthreads ), which will make developing a good performing webserver a really hard task.

He walks you through all the code needed to create the web server (also available on GitHub) by making:

• A "server" that does the listening for incoming and sends outgoing requests
• A request object that parses the incoming request and makes header and body content available
• A response object that allows for the setting of response codes, body content and headers
• Exception handling for problems encountered during the request/response process

The full code is provided during the process along with explanations of what each part does. There's also a basic introduction to what a typical web server is and how the process of request/response usually flows.