The Command Bus pattern relies on 3 types of classes:
The first one is the Command [...] next is the Command Handler [and] finally there's a Command Bus interface allowing us to build Middlewares.
For each of these parts of the design pattern he covers what the part is and how it fits into the overall structure the pattern defines. He also looks at how it allows for easier adherence to the ideas of both "clean" and "pragmatic" code. The post ends with an example of implementing the Command Bus pattern in a Symfony-based application, building out each part and their integration.