Handling Domain Events: Missing Part
Some time ago I wrote post about publishing and handling domain events. In addition, in one of the posts I described the Outbox Pattern, which provides us At-Least-Once delivery when integrating with external components / services without using the 2PC protocol. This time I wanted to present a combination of both approaches to complete previous posts. I will present a complete solution that enables reliable data processing in the system in a structured manner taking into account the transaction boundary.
The Outbox Pattern
Sometimes, when processing a business operation, you need to communicate with an external component in the Fire-and-forget mode. The question that arises is whether we are able to guarantee the atomicity of our business operation from a technical point of view?
How to publish and handle Domain Events
Domain Event is one of the building blocks of Domain Driven Design. It is something that happened in particular domain and it captures memory of it. We create Domain Events to notify other parts of the same domain that something interesting happened and these other parts potentially can react to.
Processing multiple aggregates - transactional vs eventual consistency
When we use Domain Driven Design approach in our application, sometimes we have to invoke some method on multiple instances of aggregate of the same type.