Command & Query Domain - Introduction - CQS interfaces

CQD_Introduction_Interfaces.cs

// Each action which mutates Domain's state implements this interface 
public interface ICommandHandler<TCommand>
{
   void Handle(TCommand command);
}

// Each action which queries the Domain implements this interfaces
public interface IQuery<TResult> { }

public interface IQueryHandler<TQuery, TResult> where TQuery : IQuery<TResult>
{
    TResult Handle(TQuery query);
}