...

@Entity
class Product {

    private float price;
    
    //...
    
    public void cutPrice(int percent) {    
        checkState(percent < 100);
        this.price = 
                price - price * percent / 100;
        DomainEvents.publish(
                new NewPriceAssigned(percent, this.id));
    
    }

}

 def 'should cut price by 10 percent'() {
        given:
            ShopItem item = newWithPrice(50.00)
        when:
            item.cutPrice(10)
        then:
            item.price == 45.00
    }

 def 'should cut price by procent'() {
        given:
            ShopItem item = newWithPrice(50)
        when:
            item.cutPrice(10)
        then:
            item.getUncommittedChanges() ==
                        [new NewPriceAssigned(price: 45)]
    }

QUERIES

message broker

Shop

UI

  @StreamListener("items")
  public void itemEventStream(ItemPaid itemPaid) {
        log.info("Received item paid event {}", itemPaid);
        readModel.markItemAsPaid(itemPaid.getUuid(), 
                                 itemPaid.getWhen());
  }

   @Publisher(channel = "items")
   public ItemPaid ship(ItemPaid itemPaid) {
        log.info("sending:  {}", itemPaid);
        return itemPaid;
   }

spring.cloud.stream.bindings.items.destination=items