Axon Framework CQRS Tutorial — Step by Step (2026)

Canonical URL: Republished from munonye.com. Full microservices hub: munonye.com/microservices-tutorials/

What you'll build

• Command side: CreateOrderCommand → OrderAggregate → OrderCreatedEvent
• Event store: Axon Server
• Query side: OrderProjection → H2 read model → REST GET

Prerequisites: Java 17+, Spring Boot 3.x, Axon Server

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Step 1 — Dependencies

<dependency>
  <groupId>org.axonframework</groupId>
  <artifactId>axon-spring-boot-starter</artifactId>
  <version>4.9.3</version>
</dependency>

Step 2 — Configure Axon Server

axon.axonserver.servers=localhost:8124
spring.application.name=order-service

Run ./axonserver — UI at http://localhost:8024.

Step 3 — Aggregate

@Aggregate
public class OrderAggregate {
  @AggregateIdentifier private String orderId;

  @CommandHandler
  public OrderAggregate(CreateOrderCommand cmd) {
    AggregateLifecycle.apply(new OrderCreatedEvent(cmd.getOrderId(), cmd.getProductId()));
  }

  @EventSourcingHandler
  public void on(OrderCreatedEvent event) {
    this.orderId = event.getOrderId();
  }
}

Step 4 — Query projection

@EventHandler
public void on(OrderCreatedEvent event) {
  repo.save(new OrderView(event.getOrderId(), event.getProductId(), "CREATED"));
}

Step 5 — REST

• POST /orders → CommandGateway.send(CreateOrderCommand)
• GET /orders/{id} → read from OrderViewRepository

Full code walkthrough with curl tests: read on munonye.com →

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About the author

Kindson Munonye — GitHub · LinkedIn · About