Architecture: CQS, Business Logic

Question

I'm thinking of applying the CQS pattern to my new project. I just wanna separate my queries and commands in a simpler way (I don't need fully CQRS approach). I don't want to put them all in a one class.

I have a couple of questions:

• Does it make sense to apply CQS without using a command/query dispatcher like MediatR? I mean, I don't want to apply a use-case/handler approach per each model. I just wanna use common command and query classes such as "MoviesCommandService", "MoviesQueryService".
• Sometimes we can have different business logics than CRUD operations or we need to implement patterns like strategy pattern. For example, I need to consume a few movie APIs according to a business strategy and some algorithms. Let's assume I have implemented the strategy design pattern to consume those movie APIs for different vendors. Where do these strategy pattern implementations need to take place? In Command or Query parts? Also how can I name it? Are there any restrictions when you are following command/query handlers approach or usecase approach, and you can not create normal business service classes?

Because I'm thinking of creating an interface called IMovieAPIStrategy, and implementing its concretes. Then use this interface in any query or command handlers. Is that correct approach?

Answer 1

The query/command handlers themselves can always take their own dependencies via the constructor with IoC. So if you have some shared logic API you want to reuse, you can inject that into the handler. The big power with using this pattern is the decorators you can add because you can code cross-cutting concerns in a single class that applies to all handlers and not have to redo that logic hundreds of times. You just get it for free, essentially (which MediatR can help with).