Question

A while back I asked a question revolving around how to copy a file in chunks from one location to another: CopyFileEx "The parameter is invalid" error

I received the following code which was quite helpful.

    static void chunkCopyFile(string source, string destination, int bytesPerChunk)
    {
        uint bytesRead = 0;

        using (FileStream fs = new FileStream(source, FileMode.Open, FileAccess.Read)) {
            using (BinaryReader br = new BinaryReader(fs)) {
                using (FileStream fsDest = new FileStream(destination, FileMode.Create)) {
                    BinaryWriter bw = new BinaryWriter(fsDest);
                    byte[] buffer;

                    for (int i = 0; i < fs.Length; i += bytesPerChunk) {
                        buffer = br.ReadBytes(bytesPerChunk);
                        bw.Write(buffer);
                        bytesRead += Convert.ToUInt32(bytesPerChunk);
                        updateProgress(bytesRead);
                    }
                }
            }
        }
    }

However, I now need to convert this code to use FTP instead. I tried the obvious of just passing the FTP path to the filestream but it gave me an error saying “unsupported”.

I already managed to get the file length, I’m just not sure how I can split the download into chunks. Any help is appreciated as always!

Code so far(not much)

static void chunkCopyFTPFile(string destination, int bytesPerChunk)
    {
        uint bytesRead = 0;

        fWR = (FtpWebRequest)WebRequest.Create("ftp://" + FTP_SERVER_NAME + "/test.txt");
        fWR.Method = WebRequestMethods.Ftp.DownloadFile;
        fWR.UseBinary = true;

        fWR.Credentials = new NetworkCredential(FTP_SERVER_USERNAME, FTP_SERVER_PASSWORD);

        FtpWebResponse response = (FtpWebResponse)fWR.GetResponse();

        Stream responseStream = response.GetResponseStream();
        StreamReader sR = new StreamReader(responseStream);

        sR.ReadToEnd();

        sR.Close();
        response.Close();
    }

Final code (working):

using (Stream responseStream = response.GetResponseStream()) {
            using (BinaryReader bR = new BinaryReader(responseStream)) {
                using (FileStream fsDest = new FileStream(destination, FileMode.Create)) {
                    BinaryWriter bw = new BinaryWriter(fsDest);
                    int readCount;
                    byte[] buffer = new byte[bytesPerChunk];

                    readCount = responseStream.Read(buffer, 0, bytesPerChunk);
                    bytesRead += Convert.ToUInt32(readCount);
                    updateProgress(bytesRead);

                    while (readCount > 0) {
                        bw.Write(buffer, 0, readCount);
                        readCount = responseStream.Read(buffer, 0, bytesPerChunk);
                        bytesRead += Convert.ToUInt32(readCount);
                        updateProgress(bytesRead);
                    }
                }
            }
        }

Answer 1

Ok here is what you could try. This code is not tested. So if it contains errors and you get it work please edit answer or point me to mistakes.

static void chunkCopyFile(string source, string destination, int bytesPerChunk)
{
    uint bytesRead = 0;
    //Instead of this:
    //using (FileStream fs = new FileStream(source, FileMode.Open, FileAccess.Read)) {

    //...some necessary stuff...
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://www.contoso.com/test.htm");
    request.Method = WebRequestMethods.Ftp.DownloadFile;
    request.Credentials = new NetworkCredential ("anonymous","[e-mail]");
    FtpWebResponse response = (FtpWebResponse)request.GetResponse();

    //Use this:
    using(Stream fs = response.GetResponseStream()){

        using (BinaryReader br = new BinaryReader(fs)) {
            using (FileStream fsDest = new FileStream(destination, FileMode.Create)) {
                BinaryWriter bw = new BinaryWriter(fsDest);
                long cl = response.ContentLength;
                int bufferSize = 2048;
                int readCount;
                byte[] buffer = new byte[bufferSize];

                readCount = fs.Read(buffer, 0, bufferSize);
                while (readCount > 0)
                {
                   bw.Write(buffer, 0, readCount);
                   readCount = fs.Read(buffer, 0, bufferSize);
                   updateProgress(readCount);
                }
            }
        }
    }
}

References:

http://msdn.microsoft.com/en-us/library/ms229711

http://www.codeproject.com/Articles/17202/Simple-FTP-demo-application-using-C-Net-2-0 (Download method code)