ReactPHP is an event-driven, non-blocking I/O library. This library relies essentially on an event loop that polls file descriptors, uses timers and defers callbacks by registering and executing outstanding ticks on each iteration of the loop.

ReactPHPis based on the Reactor pattern which, according to Douglas C. Schmidt, is a "design pattern that handles service requests that are delivered concurrently to an application by one or more clients. Each service in an application may consist of several methods and is represented by a separate event handler that is responsible for dispatching service-specific requests. Dispatching of event handlers is performed by an initiation dispatcher, which manages the registered event handlers. Demultiplexing of service requests is performed by a synchronous event demultiplexer." In Schmidt’s original paper Reactor: An Object Behavioral Pattern for Demultiplexing and Dispatching Handles for Synchronous Events, we can find this UML...