Spring Boot Starter for Axon Framework

This software is in the Public Domain. Please see LICENSE.md.

I no longer maintain this repo but keep it for reference for other.

Acknowledgment

This project is heavily indebted to:

• Lieven Doclo
• Christopher Elkins
• Tom Soete

Features

• Autoconfiguration driven with standard @EnableAutoConfiguration and META-INF/spring.factories. Include the jar in your classpath and add the annotation to a configuration class.
• Autoconfigure CommandBus and EventBus with default implementations. In particular, your configuration must define a bean for EventStore: there are too many strategies for event stores for autoconfiguration to pick a default one for you.
• Autoconfigure aggregate root repositories marked with @MetaInfServices. The matching repository bean is the aggregate bean name appended with "Repository" ("fooRoot" becomes "fooRootRepository"). These generate entries in /META-INF/services/org.axonframework.eventsourcing.annotation.AbstractAnnotatedAggregateRoot. Note you must annotate injected repository fields with @Qualified(name-of-repostiroy) because of limitations in Spring's support for generics.
• Autoconfiguration for event bus clusters.
• Autoconfiguration for JGroups distributed command bus.
• Autoconfiguration for event processing monitors.
• Autoconfiguration for Spring Messaging event cluster.
• Autoconfiguration for command dispatch and handler interceptors.
• Autoconfiguration for audit and monitoring.

Minimal Example

Read-side configuration

Include axon-spring-boot-starter-query in your dependencies.

@Configuration
@EnableAutoConfiguration
public class AConfiguration {}

Write-side configuration

Include axon-spring-boot-starter in your dependencies.

@Configuration
@EnableAutoConfiguration
public class AConfiguration {
    @Bean
    public EventStore eventStore() {
        return ...;
    }
}

Aggregate root and repository

Include axon-spring-boot-starter in your dependencies.

@MetaInfServices
public class SomeAggregateRoot
        extends AbstractAnnotatedAggregateRoot<SomeIDType> {
    @AggregateIdentifier
    private SomeIDType id;
}

@Component
public final class SomeClassUsingRespository {
    @Autowired
    @Qualifier("someAggregateRootRepository")
    private Repository<SomeAggregateRoot> repository;
}

JGroups command bus

Include axon-spring-boot-starter-distributed-commandbus in your dependencies.

@Configuration
@EnableAutoConfiguration
public class AConfiguration {
    @Bean
    public EventStore eventStore() {
        return ...;
    }
}

In your application.yaml:

axon:
  jgroups:
    cluster-name: TEST

And include a suitable jgroups-config.xml in your classpath.

Command dispatch interceptors

@Order(1)
public class ADispatchInterceptor implements CommandDispatchInterceptor {
    // ...
}

Exposed as a bean, such interceptors are invoked in order.

Command handler interceptors

@Order(1)
public class AHandlerInterceptor implements CommandHandlerInterceptor {
    // ...
}

Exposed as a bean, such interceptors are invoked in order.

Event processing monitor

Include axon-spring-boot-starter-clustering-eventbus in your dependencies.

Note: all monitors subscribe to all clusters in the Spring context.

@Component
public final class SomeEventProcessingMonitor
        implements EventProcessingMonitor {
    @Override
    public void onEventProcessingCompleted(
            final List<? extends EventMessage> eventMessages) {
    }

    @Override
    public void onEventProcessingFailed(
            final List<? extends EventMessage> eventMessages,
            final Throwable cause) {
    }
}

Spring messaging

Include axon-spring-boot-start-springmessaging in your dependencies.

@Configuration
@EnableAutoConfiguration
public class AConfiguration {
    @Bean
    public SubscribableChannel subscribableChannel() {
        return ...;
    }
}

A typical implementation uses JMS (spring-jms dependency).

Spring Boot auditing

@Configuration
@EnableAutoConfiguration
public class AConfiguration {
    @Bean
    public AuditEventRepository auditEventRepository() {
        return ...;
    }
}

Include axon-spring-boot-start-monitoring in your dependencies. Both commands and events are audited through Spring Boot.

Releases

5

• Autoconfiguration of command dispatch and handler interceptors
• Flow of metadata from initial command through consequences

4

• Event processing monitor automation.
• Spring Messaging support.

3

• Read-side (query) uses autoconfiguration as well as write-side.
• Clustering event bus starter.

2

• Renamed project and modules to meet Spring Boot 3rd-party naming guidelines. So spring-boot-axon-starter becomes axon-spring-boot-starter. Apologies committers and cloners. Better now than later.

1

• Break project into multi-module reactor build. Separate axon starters in separate modules.
• Support JGroups distriuted command bus.

0

• Basic functionality, single project, simple defaults for Axon components