In your application, you probably have created a couple of components:
- client code that issues commands
- a command handling component
- an event handling component
But how does Axon Framework call these components precisely? The reference guide explains all available infrastructure components, but does not have an overview how and when each component is called.
Below you find a presentation that addresses this question of "How do they do it"; it shows the flow of starting up an Axon application, and the steps and framework components involved in handling a command message and any resulting event messages.
The code that you see is from the cookbook recipe Simple application using Axon Framework and Spring Boot, and revolves around a simple banking application that allows you to create accounts and deposit to or withdraw money from that account. In the walkthrough, I'll follow a command to withdraw some money from an account aggregate that was created earlier.
I'm using the Axon Spring Boot Starter, so this walkthrough uses a SimpleCommandBus, event sourced Aggregates and Subscribing Event Processors. In the future I may expand on this by creating some more walkthroughs, but then for asynchronous command or event processing.
If you'd like to learn more about the inner workings of the Axon Framework, we host regular training.
(below you should see an embedded slide show, if it does not show, you can also see it here)