Implement Domain Agent

• For each agent there will be an abstract class Agent Base generated in the SDK.

• The Agent Base provide access to the repository, entity builder, event builder and event producer.

• The Agent Base contains one abstract method named onMessage.

• The onMessage method needs to be implemented in the generated implementaion file for the agent.

• The Agent implementation file onMessage is automatically triggered when the kafka event that the agent is modelled aganist is recieved.

• Agent onMessage method will recieve Payload Entity as first paramter (if event that the agent recieves is modelled with a payload).

• Agent onMessage method will also recieve MessageHeaders as a paramter which is a key-value map that contains kafka message headers.

• If agent is modelled with business events, for each event there will be an inherited method in the agent base class that takes the event as an input and publishes it.

• It is also possible to publish events directly using EventProducerService.

Example of Balance service implemenation file.

    package de.knowis.cards.operations.domain.cc.agent;

    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.stereotype.Service;
    import org.springframework.messaging.MessageHeaders;

    import de.knowis.cards.operations.sdk.domain.cc.agent.CreditCardCreatedAgentBase;
    import de.knowis.cards.operations.domain.facade.DomainEntityBuilder;
    import de.knowis.cards.operations.domain.facade.DomainEventBuilder;
    import de.knowis.cards.operations.sdk.domain.facade.Repository;
    import de.knowis.cards.operations.sdk.domain.service.EventProducerService;
    import de.knowis.cards.operations.sdk.domain.cc.entity.CreditCard;
    import de.knowis.cards.operations.sdk.domain.cc.entity.Card;

    @Service
    public class CreditCardCreatedAgent extends CreditCardCreatedAgentBase {

      private static Logger log = LoggerFactory.getLogger(CreditCardCreatedAgent.class);

      // Declare Card Command 
      private final CardCommandBase cardCommand;

      // Adjust your generated agent constructor to inject CardCommandBase so it can be used in agent logic
      public CreditCardCreatedAgent(DomainEntityBuilder entityBuilder, DomainEventBuilder eventBuilder, EventProducerService eventProducer, Repository repo, CardCommandBase cardCommand) {
        super(entityBuilder,eventBuilder, eventProducer,repo);
        this.cardCommand = cardCommand;
      }

      
      @Override
      public void onMessage(CreditCard creditCard, MessageHeaders headers) {

        log.info("Agent CreditCardCreatedAgent received event cc:CreditCardCreated");

        // Get root entity through repository
        Card card = this.repo.getCc().getCards().findById(creditCard.getId());

        // Call activateCard instance command to activate Card 
        // (this will call implemented logic for activate card command)
        cardCommand.activateCard(card);

      }

    }