BL Exceptions

public class FileNotSupportedException : Exception
{
public FileNotSupportedException(string mes) : base(mes)
{

 }

}

public class ItemNotFoundException : Exception
{
public ItemNotFoundException(string mes) : base(mes)
{

 }

}

public class OperationNotValidException : Exception
{
public OperationNotValidException(string mes) : base(mes)
{

 }

}