axon-kafka-example

Example of axon-kafka module usage. This example uses Spring Boot 2.0 and Axon Framework. It's a good starting point for event driven development.

Here the link to the official documentation for axon-kafka https://docs.axonframework.org/part-iii-infrastructure-components/event-processing#apache-kafka

Producer

Produces events which are consumed by the consumer.

Producer-events

Every public API represents a contract. When using message the exchanged messages are the contracts. In this example the contract is the MyEvent

Consumer

Cosumer is there to consume the published event by the producer. Therefor is the @EventHandler is needed which is automatically scanned by the Axon framework and assigned to the trackingProcessor matching the ProcessingGroup

axon:
  eventhandling:
    processors:
      "[MyProcessor]":
        source: kafkaMessageSource
        mode: TRACKING

In our example you can find the name MyProcessor. This is the name you can find in the @EventHandler class

@Component
@ProcessingGroup("MyProcessor")
public class MyEventEventHandler {

  private static final Logger LOGGER = LoggerFactory.getLogger(MyEventEventHandler.class);

  @EventHandler
  public void handleMyEvent(MyEvent myEvent){
    LOGGER.debug("got the event {}", myEvent);
  }

}

For reference see the Spring Boot Autoconfiguraton https://docs.axonframework.org/part-ii-domain-logic/event-handling

###Docker If you don't have a kafka environment running on your machine, you can use the docker-compose.yaml here. All you need to do is to navigate to this directore and execute the command

gradlew build docker
docker-compose up