CQRS

Used in 126 java projects (avg ★307)

Used by 126 projects

Language / Topic

Java

Rules

CQRS · balanced balanced

- Separate commands (mutations) and queries (reads) into distinct service classes or handler methods.

- Use `CommandHandler` and `QueryHandler` interfaces for type-safe dispatching.

- Use separate read and write repositories — query side can use raw SQL or projections for performance, command side uses rich domain models.

- Use Spring's `ApplicationEventPublisher` or a mediator library for command/query dispatching.

- Optimize read paths independently: use JPA projections, `@Query` with native SQL, or read replicas.

- Validate commands with Bean Validation before handling. Commands carry only validated data.

- Use separate DTOs for commands (input) and queries (output).