On PHPMaster.com there's a new tutorial that introduces you to React, the PHP-based event-driven non-blocking socket tool that's similar to some of the functionality Node.js provides. The article is a very basic introduction but can help get your feet wet with the tool.
For the past couple of years, Node.js has been drawing increasing amounts of attention as a promising web technology. While it has some strengths, like being event driven, some people just want to stick to PHP. For over a year now, however, there has been a similar project for PHP named React. React is mostly coded by Igor Wiedler, who is also a prominent contributor to the Silex framework. While reading through the React examples, it really does look similar to Node.js.
Included in the post are the instructions on how to get the latest version of React (via Composer) and the code to create a sample server that just writes out a string with a counter for the number of requests made. There's also an example of a "keystroke logger" for all data that's coming across the connection. The author (Igor) notes, however, that he wouldn't recommend using React in production, though, as its target is mostly those working with "cutting-edge technologies" rather than more stable applications.