Dependency Graph

Class Diagram

Introduction

Semantically, domain and integration events are the same thing: notifications about something that just happened. However, their implementation must be different. Domain events are just messages pushed to a domain event dispatcher, which could be implemented as an in-memory mediator based on an IoC container or any other method.

On the other hand, the purpose of integration events is to propagate committed transactions and updates to additional subsystems, whether they are other microservices, Bounded Contexts or even external apps. Hence, they should occur only if the entity is successfully persisted, otherwise it's as if the entire operation never happened.

As mentioned before, integration events must be based on asynchronous communication between multiple microservices (other Bounded Contexts) or even external systems/apps.

Thus, the event bus interface needs some infrastructure that allows inter-process and distributed communication between potentially remote services. It can be based on a commercial service bus, queues, a shared database used as a mailbox, or any other distributed and ideally push based messaging system.(see: Domain events: Design and implementation).

©Should you publish Domain Events or Integration Events?

©Implementing event-based communication between microservices (integration events)