Delphi ActiveX

Pre-Allocate Server Space Before an FTP Upload (ALLO)

Demonstrates the AllocateSize property, which sends the FTP ALLO command to pre-allocate disk space on the server before an upload. Set it to the size in bytes of the file about to be uploaded.

Background: ALLO asks the server to reserve storage in advance, a requirement of certain legacy systems — older mainframes in particular — that need the exact file size up front to allocate a dataset. Modern servers allocate space dynamically and typically ignore or accept ALLO without needing it, so most applications never set this. Provide it only when targeting a host known to require pre-allocation.

Chilkat Delphi ActiveX Downloads

Download Chilkat for Delphi ActiveX

Delphi ActiveX

var
success: Integer;
ftp: TChilkatFtp2;

begin
success := 0;

ftp := TChilkatFtp2.Create(Self);

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';

success := ftp.Connect();
if (success = 0) then
  begin
    Memo1.Lines.Add(ftp.LastErrorText);
    Exit;
  end;

//  AllocateSize sends the FTP ALLO command to pre-allocate disk space on the server before an
//  upload.  It is rarely needed -- mainly for certain legacy systems that require the exact size
//  in advance -- since most servers allocate space dynamically.  Set it to the size in bytes of
//  the file about to be uploaded.
ERROR: Assignment type mismatch.  ExpressionType=int, atgType=uint

success := ftp.PutFile('qa_data/bigfile.zip','uploads/bigfile.zip');
if (success = 0) then
  begin
    Memo1.Lines.Add(ftp.LastErrorText);
    Exit;
  end;
Memo1.Lines.Add('Uploaded with pre-allocation.');

success := ftp.Disconnect();
if (success = 0) then
  begin
    Memo1.Lines.Add(ftp.LastErrorText);
    Exit;
  end;