In this section, you will learn how to install and use the Ratchet framework. It's important to note that Ratchet applications work differently than regular PHP applications that are deployed in a web server and work on a per-request basis. This will require you to adopt a new way of thinking of how PHP applications are run and deployed.
Implementing a WebSocket server with PHP is not trivial. Traditionally, PHP's architecture revolves around the classical request/reply paradigm: the web server receives a request, passes it to the PHP interpreter (which is typically built into the web server or managed by a process manager such as PHP-FPM), which processes the request and returns a response to the web server who in turn responds to the client. The lifetime of data in a PHP script is limited to a single request (a principle that is called Shared Nothing).
This works well for classical web applications; especially the Shared Nothing principle...