Understanding CQRS: Command Query Responsibility Segregation
Here’s a diagram that explains the CQRS (Command Query Responsibility Segregation) pattern. I’ll first describe it in detail and then provide the image: Diagram Description Client: The user interface or API that sends commands and queries. Command: Represents an action that changes the state of the system (e.g., CreateOrder, UpdateCustomer). Query: Represents a request for data without changing the state (e.g., GetOrder, GetCustomerDetails). Command Handler: Processes the command and updates the data in the Write Model. Write Model (Data Store): The data store where the state-changing operations are performed. Event: Represents the outcome of a command and is used to update other parts of the system. Event Store: Stores the events generated by command handlers. Event Handler: Listens to events and updates the Read Model. Read Model (Data Store): Optimized for read operations, often denormalized for fast querying. 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. ...