Understanding CQRS: Command Query Responsibility Segregation
Understanding CQRS: Command Query Responsibility Segregation Command Query Responsibility Segregation (CQRS) is an architectural pattern that separates read and write operations into distinct models. This separation allows for optimization of each model independently, addressing different requirements and scaling needs. Core Components of CQRS flowchart TD Client[Client Application] --> Commands[Commands] Client --> Queries[Queries] Commands --> CommandHandler[Command Handler] Queries --> QueryHandler[Query Handler] CommandHandler --> WriteModel[Write Model/Domain Model] WriteModel --> EventStore[Event Store] EventStore --> ReadModelProjection[Read Model Projection] ReadModelProjection --> ReadModel[Read Model] QueryHandler --> ReadModel ReadModel --> QueryResults[Query Results] QueryResults --> Client Key Components and Their Responsibilities: Commands: Instructions to change state (e.g., CreateOrder, UpdateCustomer). Queries: Requests for information without state changes. Command Handler: Processes commands and applies them to the write model. Write Model: The domain model with rich business logic. Event Store: Records all state-changing events as the source of truth. Read Model Projection: Processes events to update the read model. Read Model: Optimized for querying, often denormalized for performance. Query Handler: Retrieves data from the Read Model in response to queries. The separation of write and read models allows for independent optimization, scalability, and security for both operations. ...