Spring Boot Integration

Axon Framework provides extensive support for Spring Boot through its Spring Boot Starter extension. While Axon can be configured programmatically without Spring, the Spring Boot integration provides the easiest way to get started through automatic configuration.

Getting started

To enable Spring Boot auto-configuration, add the Axon Spring Boot Starter dependency to your project:

  • Maven

  • Gradle

<dependency>
    <groupId>org.axonframework.extensions.spring</groupId>
    <artifactId>axon-spring-boot-starter</artifactId>
    <version>${axon.version}</version>
</dependency>
implementation 'org.axonframework.extensions.spring:axon-spring-boot-starter:${axonVersion}'

With this dependency in place, Axon will automatically:

  • Detect and register all message handlers (command handlers, event handlers, query handlers)

  • Configure the command bus, event bus, and query bus

  • Set up event processors to handle events

  • Configure entities and repositories

  • Wire all components together

Infrastructure configuration

The Spring Boot Starter will automatically configure the necessary infrastructure based on what’s available:

Axon Server (recommended)

If the Axon Server connector is on the classpath, Axon will automatically connect to Axon Server (by default at localhost:8124) and use it for:

  • Command routing and distribution

  • Event storage and distribution

  • Query routing and distribution

You can disable Axon Server integration by setting axon.axonserver.enabled=false in your application properties.

JPA fallback

If Axon Server is not available or disabled, Axon will use JPA-based implementations for Event storage.

Extension-based implementations

Other extensions can provide additional implementations:

  • PostgreSQL event store (via the PostgreSQL extension)

Component detection

The Spring Boot Starter automatically detects Axon components in your application:

  • Methods on Spring beans that are annotated with @CommandHandler, @EventHandler, or @QueryHandler are automatically registered

  • Classes annotated with @EventSourced are registered as entities

  • All detected components are wired with the appropriate buses and infrastructure

Customization

The auto-configuration is non-intrusive and only configures components that you haven’t explicitly defined. You can override any auto-configured bean by defining your own in a @Configuration class.

For detailed configuration options, see the specific sections in this reference guide for commands, events, queries, and entities.