MSA Data Mgmt patterns -> Domain event

Domain event

Context
A service often needs to publish events when it updates its data. These events might be needed, for example, to update a CQRS view. Alternatively, the service might participate in an choreography-based saga, which uses events for coordination.

Problem
How does a service publish an event when it updates its data?

Solution
Organize the business logic of a service as a collection of DDD aggregates that emit domain events when they created or updated. The service publishes these domain events so that they can be consumed by other services.

Related patterns

·         The Saga and CQRS patterns create the need for this pattern

·         The Aggregate pattern is used to structure the business logic

·         The Transactional outbox pattern is used to publish events as part of a database transaction

·         Event sourcing is sometimes used to publish domain events