Save to isolated storage directly in WP8

Question

I want to save a zip file directly to isolated storage from server , But the problem i am facing was when i try to save using the below code , i get out of memory exception sinc

Answer 1

Then maybe try such an approach - do it with HttpWebRequest:

1. First extend your HttpWebRequest with awaitable GetResponseAsync - WP lacks this method, but with TaskCompletitionSource you can write your own implementation. Somwhere in your Namespace, make a static class:

public static class Extensions
{
    public static Task GetResponseAsync(this HttpWebRequest webRequest)
    {
        TaskCompletionSource taskComplete = new TaskCompletionSource();
        webRequest.BeginGetResponse(
            asyncResponse =>
            {
                try
                {
                    HttpWebRequest responseRequest = (HttpWebRequest)asyncResponse.AsyncState;
                    HttpWebResponse someResponse = (HttpWebResponse)responseRequest.EndGetResponse(asyncResponse);
                    taskComplete.TrySetResult(someResponse);
                }
                catch (WebException webExc)
                {
                    HttpWebResponse failedResponse = (HttpWebResponse)webExc.Response;
                    taskComplete.TrySetResult(failedResponse);
                }
                catch (Exception exc) { taskComplete.SetException(exc); }
            }, webRequest);
        return taskComplete.Task;
    }
}

2. Then modify your code to use it:

CancellationTokenSource cts = new CancellationTokenSource();
enum Problem { Ok, Cancelled, Other };

public async Task DownloadFileFromWeb(Uri uriToDownload, string fileName, CancellationToken cToken)
{
    try
    {
        HttpWebRequest wbr = WebRequest.CreateHttp(uriToDownload);
        wbr.Method = "GET";
        wbr.AllowReadStreamBuffering = false;
        WebClient wbc = new WebClient();

        using (HttpWebResponse response = await wbr.GetResponseAsync())
        {
            using (Stream mystr = response.GetResponseStream())
            {
                using (IsolatedStorageFile ISF = IsolatedStorageFile.GetUserStoreForApplication())
                  {
                      if (ISF.FileExists(fileName)) return Problem.Other;
                      using (IsolatedStorageFileStream file = ISF.CreateFile(fileName))
                      {
                          const int BUFFER_SIZE = 100 * 1024;
                          byte[] buf = new byte[BUFFER_SIZE];

                          int bytesread = 0;
                          while ((bytesread = await mystr.ReadAsync(buf, 0, BUFFER_SIZE)) > 0)
                          {
                              cToken.ThrowIfCancellationRequested();
                              file.Write(buf, 0, bytesread);
                          }
                      }
                  }
                  return Problem.Ok;
              }
          }
      }
      catch (Exception exc)
      {
          if (exc is OperationCanceledException)
              return Problem.Cancelled;
          else return Problem.Other; 
      }
  }

3. And download:

  private async void Downlaod_Click(object sender, RoutedEventArgs e)
  {
      cts = new CancellationTokenSource();
      Problem fileDownloaded = await DownloadFileFromWeb(new Uri(@"http://filedress/myfile.txt", UriKind.Absolute), "myfile.txt", cts.Token);
      switch(fileDownloaded)
      {
          case Problem.Ok:
              MessageBox.Show("Problem with download");
              break;
          case Problem.Cancelled:
              MessageBox.Show("Download cancelled");
              break;
          case Problem.Other:
          default:
              MessageBox.Show("Other problem with download");
              break;
      }
  }

As I've my WebResponse, I get a stream from it and then read it async.
Please be aware that I've not tested the code above, but hopefuly it may give you some ideas how this can work.