VB.NET

Enable FTP MODE Z Compression

Demonstrates the Chilkat Ftp2.SetModeZ method, which enables MODE Z compression for subsequent data connections. It takes no arguments. Call it after connecting and only when the HasModeZ property is true.

Background: MODE Z compresses data on the fly (using zlib) as it crosses the wire, which can meaningfully speed up transfers of compressible content — text, HTML, logs — over a slow link. It is a server extension, so check HasModeZ first and expect it to be unavailable on many servers. There is little benefit for already-compressed data such as images or archives, where the CPU cost of compression buys almost nothing.

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Dim success As Boolean = False

'  Demonstrates the Ftp2.SetModeZ method, which enables MODE Z compression for subsequent data
'  connections.  It takes no arguments.  Call it after connecting, and only when the HasModeZ
'  property indicates the server supports it.

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


success = ftp.ChangeRemoteDir("public_html")
If (success = False) Then
    Debug.WriteLine(ftp.LastErrorText)
    Exit Sub
End If


'  Only enable compression if the server advertises MODE Z support.
If (ftp.HasModeZ) Then
    success = ftp.SetModeZ()
    If (success = False) Then
        Debug.WriteLine(ftp.LastErrorText)
        Exit Sub
    End If

    Debug.WriteLine("MODE Z compression enabled.")
Else
    Debug.WriteLine("The server does not support MODE Z.")
End If


'  Subsequent uploads, downloads, and listings are transferred compressed.

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