Gonzalo Ayuso has put together a post showing how (by implementing the Reactor design pattern) he created a simple web server inside a PHP application. It combines a few Symfony2 components and the React library to build a simple server in a bit more programatic way.
Normally we deploy our PHP applications in a webserver (such as apache, nginx, …). I used to have one apache webserver in my personal computer to play with my applications, but from time to now I prefer to use PHP’s built-in webserver for my experiments. It’s really simple. [...] With PHP we cannot do it. Sure? That assertion isn’t really true. We can do it. I’ve just create one small library to do it in two different ways. First running the built-in web server and also running one React web server.
The idea is that all that would be needed is a stand-alone PHP script that could be run anywhere and start up its own web server, no other software required. He includes a simplified version of the example, showing how to make servers with both React and PHP's own server. He also includes an example of a basic Silex application that uses it as well as some benchmarks (with Apache ab) for each of the implementations and their request/response times on average for simple and Silex requests.