Axon - Event Handler Interceptor configuration

Question

I'm trying to define my "Event Handler Interceptor", I followed the instruction on the official documentation here , but I get the following error:

org.springframework.beans.factory.BeanCreationException: error when creating the bean with name 'configureEventProcessing' defined in the resource path class [com / prog / boot / config / EventProcessorConfiguration.class]: invalid factory method 'configureEventProcessing': must have an empty non-return type!

My current configuration call:

@Configuration
public class EventProcessorConfiguration {

    @Bean
    public void configureEventProcessing(Configurer configurer) {
        configurer.eventProcessing()
                  .registerTrackingEventProcessor("my-tracking-processor")
                  .registerHandlerInterceptor("my-tracking-processor",
                                              configuration -> new MyEventHandlerInterceptor());
    }
}

My event MessageHandlerInterceptor implementation:

public class MyEventHandlerInterceptor implements MessageHandlerInterceptor<EventMessage<?>> {

    @Override
    public Object handle(UnitOfWork<? extends EventMessage<?>> unitOfWork, InterceptorChain interceptorChain)
            throws Exception {
        EventMessage<?> event = unitOfWork.getMessage();
        String userId = Optional.ofNullable(event.getMetaData().get("userId")).map(uId -> (String) uId)
                .orElseThrow(Exception::new);
        if ("axonUser".equals(userId)) {
            return interceptorChain.proceed();
        }
        return null;
    }
}

What am I doing wrong?

Thanks!

Answer 1

Luckily, the problem is rather straightforward (and does not correlate to Axon directly).

The problem is you should've used @Autowired instead of @Bean on the configureEventProcessing(Configurer) method. The @Bean annotation on a method will make it a "Bean creation method", whilst you only want to tie into the auto configuration to "further configure" the Event Processors.

Final note of fine tuning, you can use the EventProcessingConfigurer as a parameter instead of the Configurer#eventProcessing call. That shortens your code just a little.

---

Update

The provided configuration would, given the auto-wiring adjustment work as expected. Granted, it does expect an Event Handling Component to be present which is part of the ""my-tracking-processor" processing group.

If there are no Event Handling components present in that processing group, no events will be passed to it and thus none will be pushed through the MessageHandlerInterceptor .

A quick and easy way to specify a processing group for an Event Handling Component is by adding the @ProcessingGroup annotation on class level.