SomeRule.cs

    public class SomeRule : IValidationRule
    {
        private readonly ISomeService _service;

        public SomeRule(ISomeService service)
        {
            _service = service;
        }

        public void Validate(ValidationContext context)
        {
            if (!_service.IsValid())
            {
                context.Notification.RegisterMessage(StringToken.FromKeyString("SomeRule"));
            }
        }
    }