Sergey Zhuk has a post on his site that covers using a Router with a ReactPHP component. This router lets you more easily direct the HTTP requests coming into the application to the correct piece of functionality.
Router defines the way your application responds to a client request to a specific endpoint which is defined by URI (or path) and a specific HTTP request method (GET, POST, etc.). With ReactPHP Http component we can create an asynchronous web server. But out of the box the component doesn’t provide any routing, so you should use third-party libraries in case you want to create a web-server with a routing system.
He starts with an example of manual routing, showing the code for a basic server and adding in handlers based on the path+HTTP verb to respond with different content. He expands this basic example out to a more "real world" situation of the usual CRUD handling for "tasks". The post then shows how to change things up and use the FastRoute routing package to remove the manual route definitions from the server and define them in the router instead. It can then dispatch these to the correct location more easily. The post finishes up showing an additional feature: how to use wildcards in these URL definitions.