org.seedstack.business.domain

Interface DomainEvent

All Superinterfaces:

Producible, ValueObject

All Known Implementing Classes:

BaseDomainEvent

public interface DomainEvent
extends ValueObject

A domain event is used to represent something that happened in the domain. It happened in the past and is of interest to the business.

A domain event always represent something that happened in the past. Its name must be in the past tense and be based upon the ubiquitous language.

A domain event can be as little as just a name. More often, it will contain values and identifiers that represent the relevant state at the time the event happened. That state should be minimized and the receivers should query the model to access additional information if necessary.

As they represent something in the past, domain events must be immutable. As such they can only contain immutable objects like value objects, primitive types, strings, etc…

Domain events are first and foremost about communication, within the system but also with other systems. A domain event should therefore be kept as simple as possible as be easy to serialize.

Example:

 public class SomeDomainEvent implements DomainEvent {
     private String attribute1;
     private String attribute2;

     public SomeDomainEvent(String attribute1, String attribute2) {
         this.attribute1 = attribute1;
         this.attribute2 = attribute2;
     }

     @Override
     public int hashCode() {
         // implement based on all attributes
     }

     @Override
     public boolean equals() {
         // implement based on all attributes
     }

     // Other methods
 }
 

See Also:

DomainEventHandler, DomainEventPublisher, ValueObject

Method Summary

Methods inherited from interface org.seedstack.business.domain.ValueObject

equals, hashCode