Failed to download files when deployed to Azure App Service

Question

Large file download code found running on IIS.

But it stops at Azure AppService.

The file will download well and then stop when it reaches 1 GB.

Is there a problem with Azure App Service settings?

Please let me know what the problem is.

This is the ashx file code.

public void ProcessRequest(HttpContext context)
{
    Stream stream = null;
 
    int bytesToRead = 10000;

    byte[] buffer = new Byte[bytesToRead];
    
    string Url = context.Request.QueryString["Url"];
    string FileName = HttpUtility.UrlEncode(context.Request.QueryString["FileName"]).Replace("+","%20");
    try
    {
        HttpWebRequest fileReq = (HttpWebRequest)HttpWebRequest.Create(Url);

        HttpWebResponse fileResp = (HttpWebResponse)fileReq.GetResponse();

        if (fileReq.ContentLength > 0)
            fileResp.ContentLength = fileReq.ContentLength;

        stream = fileResp.GetResponseStream();

        var resp = HttpContext.Current.Response;

        resp.ContentType = "application/octet-stream";
        resp.AddHeader("Content-Disposition", "attachment; filename=\"" + FileName + "\"");
        resp.AddHeader("Content-Length", fileResp.ContentLength.ToString());

        int length;
        do
        {
            if (resp.IsClientConnected)
            {
                length = stream.Read(buffer, 0, bytesToRead);

                resp.OutputStream.Write(buffer, 0, length);

                resp.Flush();

                buffer = new Byte[bytesToRead];
            }
            else
            {
                // cancel the download if client has disconnected
                length = -1;
            }
        } while (length > 0); //Repeat until no data is read
    }
    finally
    {
        if (stream != null)
        {
            //Close the input stream
            stream.Close();
        }
    }
}

score 0 · Accepted Answer · answered Nov 30 '20 at 06:40

To be honest, I didn't get any trouble using your code to download large files more than 1GB, even after publishing to Azure.

First, httpWebRequest doesn't not has any artificial size limit. I was wondering if you should consider other code to download, because it's not convenient if we couldn't see the details about the error log, and the download process.

Here is a issue might inspire you: C# - Is there a limit to the size of an httpWebRequest stream?

If you want try another code, try this:

static void Main(string[] args)
{
    HttpWebRequestDownload hDownload = new HttpWebRequestDownload();

    string downloadUrl = "http://speedtest.tele2.net/10MB.zip";
    hDownload.DownloadProgressChanged += HDownloadOnDownloadProgressChanged;
    hDownload.DownloadFileCompleted += delegate(object o, EventArgs args)
    {
        Debug.WriteLine("Download finished and saved to: "+hDownload.downloadedFilePath); 
    };
    hDownload.Error += delegate(object o, string errMessage) { Debug.WriteLine("Error has occured !! => "+errMessage); };
    hDownload.DownloadFile(downloadUrl);
}


private void HDownloadOnDownloadProgressChanged(object sender, HttpWebRequestDownload.ProgressEventArgs e)
{
    Debug.WriteLine("progress: "+e.TransferredBytes+" => "+e.TransferredPercents);
}

Failed to download files when deployed to Azure App Service

1 Answers1