VB.NET

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.

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Dim success As Boolean = False

Dim ftp As New Chilkat.Ftp2

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 = False) Then
    Debug.WriteLine(ftp.LastErrorText)
    Exit Sub
End If


'  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 = False) Then
    Debug.WriteLine(ftp.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("Uploaded with pre-allocation.")

success = ftp.Disconnect()
If (success = False) Then
    Debug.WriteLine(ftp.LastErrorText)
    Exit Sub
End If