Onion Architecture with DDD and CQRS
Onion Architecture is a design approach that aims to create a separation of concerns within the layers of an application. It is called “onion” architecture because the design is layered, with the core domain logic at the center and the outer layers representing services and infrastructure. The layers of an onion architecture are typically organized around the business domain, with the core domain logic at the center and the outer layers representing infrastructure and service concerns.
Domain-Driven Design (DDD) is a software design approach that focuses on modeling the domain of a business in order to better understand and solve business problems. DDD involves creating a rich domain model that accurately represents the complex business domain and the relationships between different domain concepts.
Command Query Responsibility Segregation (CQRS) is a design pattern that separates the responsibilities of querying data from the responsibilities of modifying data. In an event-driven microservices architecture, CQRS can be used to improve the scalability and performance of the system by allowing different services to handle queries and commands separately.
When applied in an event-driven microservices architecture, these building blocks can help to create a system that is well-organized, scalable, and maintainable. The onion architecture helps to ensure that the core domain logic is isolated from the infrastructure and services, while DDD helps to model the business domain accurately and CQRS helps to improve the scalability and performance of the system.
Explaining how I reason about the building blocks of Onion Architecture, Domain-Driven Design, and Command Query Responsibility Segregation in an event-driven microservices architecture. How it all fits together in my head, the concepts they share, and the mistakes I’ve made along the way.
Examples use modern C# but can be applied to other languages and frameworks.
About Connell
Loves building software and making music. Coding since 2005. Everyday learning and sharing knowledge.