HttpWebRequest C# uploading a file

Question

Hello,

using C#, I'm trying to integrate my web store w/ an email marketing client. I want to upload a comma delimited file of subscribers once a night. They say to get this to work, it has to be a form posts: multipart/form-data, but I'm not using a form. I'm able to connect to their servers but I keep getting back a Data can't be blank. Can anyone help me to get this working?

public static string Create()
    {
        string authInfo = "username" + ":" + "password";

        string root = AppDomain.CurrentDomain.BaseDirectory;
        string file = root + "Folder\\work.txt";

        FileInfo fi = new FileInfo(file);
        int fileLength = (int)fi.Length;

        FileStream rdr = new FileStream(file, FileMode.Open);

        HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
        httpWebRequest.Method = "POST";
        httpWebRequest.ContentType = "application/x-www-form-urlencoded";
        httpWebRequest.Accept = "application/xml";

        authInfo = Convert.ToBase64String(Encoding.Default.GetBytes(authInfo));
        httpWebRequest.Headers["Authorization"] = "Basic " + authInfo;
        byte[] requestBytes = new byte[fileLength];

        int bytesRead = 0;
        httpWebRequest.ContentLength = requestBytes.Length;
        using (Stream requestStream = httpWebRequest.GetRequestStream())
        {
            while ((bytesRead = rdr.Read(requestBytes, 0, requestBytes.Length)) != 0)
            {
                requestStream.Write(requestBytes, 0, bytesRead);
                requestStream.Close();
            }
        }
        //READ RESPONSE FROM STREAM
        string responseData;
        using (StreamReader responseStream = new StreamReader(httpWebRequest.GetResponse().GetResponseStream()))
        {
            responseData = responseStream.ReadToEnd();
            responseStream.Close();
        }
        return responseData;
    }

Answer 1

Similar to post http://stackoverflow.com/questions/566462/upload-files-with-httpwebrequest-multipart-form-data