Events

The second type of “Messages” that an Axon application is associated with are Event Messages (or simply Events). This section of the reference guide intends to cover in detail the capabilities that the Axon Framework provides to help facilitate Event Message Development.

A summary of the various sub-sections is given below.

Sub-Section Purpose
Event Dispatchers / Event Handlers Functional development for Event Messages using the Axon Framework
Event Processors / Event Bus & Event Store Non-Functional development for Event Messages using the Axon Framework
Event Serialization Details on Event serialization capabilities provided by the Axon Framework
Event Versioning Details on Event versioning capabilities provided by the Axon Framework

This guide is complemented by a video tutorial which gives a practical demonstration of the concepts explained in this section. The tutorial is available at -> Axon Coding Tutorial - Event Messages

Unit of Work Previous

Child Articles (6)

  • Event Dispatchers

    Event publication can from a couple of locations within your Axon Framework application. In general, these can be grouped in two major areas: Dispatching events from an Aggregate, and Dispatching...

  • Event Handlers

    In Axon, an object may declare a number of event handler methods, by annotating them with @EventHandler. The declared parameters of the method define which events it will receive. Axon provides...

  • Event Processors

    Event handlers define the business logic to be performed when an event is received. Event processors are the components that take care of the technical aspects of that processing. They start a unit...

  • Event Bus & Event Store

    Event Bus The EventBus is the mechanism that dispatches events to the subscribed event handlers. Axon provides three implementations of the Event Bus: AxonServerEventStore, EmbeddedEventStore and...

  • Event Versioning

    In the lifecycle of an Axon application events will typically change their format. As events are stored indefinitely the application should be able to cope with several versions of an event. This...

  • Event Serialization

    Event stores need a way to serialize the event to prepare it for storage. By default, Axon uses the XStreamSerializer, which uses XStream to serialize events into XML. XStream is reasonably fast...