cqs-patterns

To implement CQRS in a .NET application, you separate read and write concerns by defining distinct Commands and Queries, creating dedicated Handlers for each, and routing them through a Dispatcher. This enforces a strict boundary between state-changing operations and read-only requests, improving application clarity and testability.

Command Query Separation is an architectural pattern that divides operations into state-changing commands and read-only queries. You need it in .NET applications when separating read and write concerns to improve maintainability, enforce strict architectural boundaries, and support scalable designs with separate read and write models.

Structure commands and queries by creating distinct models for reads and writes across application layers. Define a CreateEntityCommand with a CommandHandler for state changes, a GetEntityQuery with a QueryHandler for reads, and wire them through a central Dispatcher to route requests to the correct handler.

No external libraries or tooling are required to apply CQRS patterns in .NET. You only need a standard .NET development environment to define commands, queries, handlers, and dispatchers, using provided code snippets and architectural guidance to implement the patterns directly.

CQS separates methods into state-changing commands and read-only queries, while CQRS extends this architectural guidance by supporting separate read and write models, dedicated handlers, and distinct data stores to improve scalability and maintainability across .NET application layers.

You should avoid separating read and write models when application complexity is low and the overhead of maintaining distinct commands, queries, handlers, and dispatchers outweighs the architectural clarity and scalability benefits gained from implementing CQRS patterns.