Question

I was just curious, is it possible to have direct network transfers in c#, without local caching.

e.g.
I have response stream which represents GoogleDrive file and request stream to upload file to another GoogleDrive account.

At that momment I can download file to local pc and next upload it to the google drive. But is it possible to upload it directly from one google drive to another or, at least, start uploading before full download will be completed.

Thank

Answer 1

Yes you can, with Google Drive api you download file into a stream and you keep it in memory so you can upload it to another google drive account after login.

You get your token on first account and download a file keeping it in a stream.

THen you authenticate on other google drive account and upload the file using the stream.

PS: When you are inserting the file on the second drive account, instead of getting
the byte[] array reading the file from disk you get the byte array from the stream you have in memory.

File Download Example:

public static System.IO.Stream DownloadFile(
      IAuthenticator authenticator, File file) {
    if (!String.IsNullOrEmpty(file.DownloadUrl)) {
      try {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(
            new Uri(file.DownloadUrl));
        authenticator.ApplyAuthenticationToRequest(request);
        HttpWebResponse response = (HttpWebResponse) request.GetResponse();
        if (response.StatusCode == HttpStatusCode.OK) {
          return response.GetResponseStream();
        } else {
          Console.WriteLine(
              "An error occurred: " + response.StatusDescription);
          return null;
        }
      } catch (Exception e) {
        Console.WriteLine("An error occurred: " + e.Message);
        return null;
      }
    } else {
      // The file doesn't have any content stored on Drive.
      return null;
    }

File insert example:

private static File insertFile(DriveService service, String title, String description, String parentId, String mimeType, String filename) {
    // File's metadata.
    File body = new File();
    body.Title = title;
    body.Description = description;
    body.MimeType = mimeType;

    // Set the parent folder.
    if (!String.IsNullOrEmpty(parentId)) {
      body.Parents = new List<ParentReference>()
          {new ParentReference() {Id = parentId}};
    }

    // File's content.
    byte[] byteArray = System.IO.File.ReadAllBytes(filename);
    MemoryStream stream = new MemoryStream(byteArray);

    try {
      FilesResource.InsertMediaUpload request = service.Files.Insert(body, stream, mimeType);
      request.Upload();

      File file = request.ResponseBody;

      // Uncomment the following line to print the File ID.
      // Console.WriteLine("File ID: " + file.Id);

      return file;
    } catch (Exception e) {
      Console.WriteLine("An error occurred: " + e.Message);
      return null;
    }
  }