Dart

Upload a Large File in Chunks (FTP)

Demonstrates the Chilkat Ftp2.LargeFileUpload method, which uploads a local file as a sequence of transfers, each up to a given chunk size. The arguments are the local path, the remote path, and the chunk size in bytes.

Note: The local paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: Some servers, proxies, or firewalls impose a limit on the size or duration of a single data transfer, which a very large file can exceed. This method sidesteps that by sending the file in pieces — the first with STOR to create or replace the file, each subsequent one appended — so no single transfer is oversized. Choose a chunk size comfortably under whatever limit you are working around.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Demonstrates the Ftp2.LargeFileUpload method, which uploads a local file as a sequence of
  // transfers, each up to a given chunk size.  The 1st argument is the local path, the 2nd is the
  // remote path, and the 3rd is the chunk size in bytes.

  final ftp = CkFtp2();

  ftp.hostname = 'ftp.example.com';
  ftp.username = 'myFtpLogin';

  // Normally you would not hard-code the password in source.  You should instead obtain it
  // from an interactive prompt, environment variable, or a secrets vault.
  ftp.password = 'myPassword';

  try {
    ftp.connect();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // The first chunk is sent with STOR (creating/replacing the remote file); each later chunk is
  // appended.  Uploading in chunks can work around server or network limits on a single transfer.
  final chunkSize = 10485760;
  try {
    ftp.largeFileUpload('qa_data/bigfile.zip', 'uploads/bigfile.zip', chunkSize);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Large file uploaded.');

  try {
    ftp.disconnect();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }
}