What is a domain event?

What is a domain event?

A domain event is, something that happened in the domain that you want other parts of the same domain (in-process) to be aware of. The notified parts usually react somehow to the events. An important benefit of domain events is that side effects can be expressed explicitly.

What is a domain event DDD?

In domain-driven design, domain events are described as something that happens in the domain and is important to domain experts. Such events typically occur regardless of whether or to what extent the domain is implemented in a software system. They are also independent of technologies.

What is unit of work in DDD?

A “Unit of Work” is basically an on-the-fly aggregate, allowing a single transactional update to a set of entities, without having to explicitly define in code an aggregate to do this. This comes at the cost of not having an explicit Aggregate class on which to put mutation methods which protect your invariants.

How do you publish and handle a domain event?

The complete process looks like this:

1. Create database transaction.
2. Get aggregate(s).
3. Invoke aggregate method.
4. Add domain events to Events collections.
5. Publish domain events and handle them.
6. Save changes to DB and commit transaction.
7. Publish domain events notifications and handle them.

What is event sourcing and CQRS?

Event sourcing is an approach to data storing where instead of just the final result of data transformation, the whole chain of transformations is stored. CQRS stands for Command Query Responsibility Segregation. It is a concept that can be tightly related to event sourcing.

What is domain service?

Domain services are Windows Communication Foundation (WCF) services that encapsulate the business logic of a WCF RIA Services application. A domain service exposes a set of related operations in the form of a service layer.

What is event sourcing in DDD?

Event Sourcing is a generalization of this idea to any other domain — Any process can be mapped by storing an ordered list of domain-related facts (aka “events”). Event Sourcing is a highly efficient write model. Events describe what has already happened, and because we cannot change the past, they are immutable.

What is domain-driven design in Microservices?

Domain-driven design is the idea of solving problems of the organization through code. The business goal is important to the business users, with a clear interface and functions. This way, the microservice can run independently from other microservices. Eventually, this creates more value for the end-user.

Where is event sourcing used?

When to Use It

1. One obvious form of return is that it’s easy to serialize the events to make an Audit Log.
2. Another use for this kind of complete Audit Log is to help with debugging.
3. Event Sourcing is the foundation for Parallel Models or Retroactive Events.

How are domain events used in Domain Driven Design?

This post relates to the Domain Driven Design (DDD) concept of Domain Events. These events originate in the Domain Model and are broadcast within a Bounded Context. These are not events used directly for integration.

How are domain events handled in order aggregate?

When the user initiates an order, the Order Aggregate sends an OrderStarted domain event. The OrderStarted domain event is handled by the Buyer Aggregate to create a Buyer object in the ordering microservice, based on the original user info from the identity microservice (with information provided in the CreateOrder command).

Where do domain events originate in the efcore model?

These events originate in the Domain Model and are broadcast within a Bounded Context. These are not events used directly for integration. For the purpose of this implementation I want to frame things as EFCore entities publishing events that can be handled locally by one or more subscribers within a Unit Of Work.

How are domain events used to enforce consistency?

Domain events to enforce consistency between multiple aggregates within the same domain Figure 7-14 shows how consistency between aggregates is achieved by domain events. When the user initiates an order, the Order Aggregate sends an OrderStarted domain event.

https://www.youtube.com/watch?v=SbMbWmmukws