Question

I have to create a program that would upload business data to the FTP site. I am developing this program in C#.

So I have created dependent classes for this program as follows

IData – to fetch the data from the database
IDataTransform – convert the data received from database to specific format as client requested
IFtpOperation – uploads the file from local disk
ISettings- It holds all the relevant configurations such connection string, FTP server location, credential etc.,

Here is the code of it

    public interface IFtpOperation
{
    void Upload(string localFilePath);
}

public interface IDataTransform<in T1, out T2>
{
    T2 Transform(T1 input);
}

public interface IData<in T1, out T2>
{
    T2 GetData(T1 input);
}

public interface ISettings
{
    T GetValue<T>(string key);
}

Then I created another class that wires these operations. The above interfaces being passed as constructor parameter to this class. This class contains a method UploadCustomerData that call the methods in dependencies as required.

Here is the code

public class UploadFileViaFTP
{
    private readonly IFtpOperation _ftp;
    private readonly IData<int, IList<CustomerData>> _customerData;
    private readonly IDataTransform<CustomerData, string> _transformer;
    private readonly ISettings _settings;

    public UploadFileViaFTP(IFtpOperation ftp, IData<int, IList<CustomerData>> customerData,
        IDataTransform<CustomerData, string> transformer, ISettings settings)
    {
        _ftp = ftp;
        _transformer = transformer;
        _customerData = customerData;
        _settings = settings;
    }

    public void WriteToDisk(IList<CustomerData> customers, string localFilePath)
    {
        using (var writer = new StreamWriter(localFilePath))
        {
            foreach (var customer in customers)
            {
                writer.WriteLine(_transformer.Transform(customer));
            }
        }
    }

    private void UploadCustomerData(int accountId)
    {
        var customerData = _customerData.GetData(accountId);
        if (customerData.Count > 0)
        {
            var localPath = _settings.GetValue<string>("LocalFilePath");
            WriteToDisk(customerData, localPath);
            _ftp.Upload(localPath);
        }
        else
        {
            _notificationMessage.AppendLine(
                string.Format("There could be an error or no data avaiable to upload at {0} for account {1}.", DateTime.Now, accountId));
        }
    }
}

Now my question is where does this class UploadFileViaFTP lives. In service layer or business layer? And please explain why is that?

I hope explained in detail.

Answer 1

It seems like it’s more like a façade (learn more here). And this is business layer.

After all, UploadFilesViaFTP should be available in service operations or in a single tier application (a good indication for living in business layer).