Axon Framework

AxonIQ is launching the first milestone of Axon Framework 5.0.0, aiming to broaden its capabilities and reduce complexity for all users through milestone releases and make it easier to configure Axon applications.

Axon Framework provides extensive support for Spring, but does not require you to use Spring in order to use Axon. All components can be configured programmatically and do not require Spring on the classpath. However, if you do use Spring, much of the configuration is made easier with the use of Spring’s annotation support. Axon provides Spring Boot starters on top of that, so you can benefit from auto-configuration.

An Event Handler is a method that is capable of handling an EventMessage. As such, the method will react to the occurrences within an application. In Axon, an object may declare several event handlers by annotating them with @EventHandler. This object is most often referred to as an Event Handling Component, or simply an Event Handler.

Apache Kafka is a popular system for publishing and consuming events. Its architecture is fundamentally different from most messaging systems and combines speed with reliability. Axon provides an extension dedicated to publishing and receiving event messages from Kafka.

The StreamingEventProcessor, or streaming processor for short, is a type of event processor. As any event processor, it serves as the technical aspect to handle events by invoking the event handlers written in an Axon application.

Building a new application from scratch can be daunting, especially when learning something new. This tutorial will guide you through the various stages of development, starting with creating your first project and explaining the capabilities of Axon Framework and Axon Server.

The flow of messages between (micro)services and storage of events requires preparation of the messages through serialization. Axon uses the XStreamSerializer by default, which uses XStream to serialize into and deserialize from XML. XStream is reasonably fast, and the result of serialization is human-readable. This makes it quite useful for logging and debugging purposes.