B4X

Throttle FTP Transfer Bandwidth

Demonstrates the bandwidth properties BandwidthThrottleUp and BandwidthThrottleDown, and the read-only UploadTransferRate and DownloadTransferRate.

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: Throttling caps the approximate transfer rate in bytes per second (0 means unlimited), which is how a background sync avoids starving interactive traffic on a shared or metered link. The rate properties report the current measured throughput, updated during transfers, so you can display progress or confirm the throttle is taking effect. Treat the limits as approximate targets rather than hard ceilings.

Chilkat B4X Downloads

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B4X

Dim success As Boolean = False

Dim ftp As ChilkatFtp2
ftp.Initialize("ftp")

ftp.Hostname = "ftp.example.com"
ftp.Username = "myFtpLogin"

'  Limit the approximate transfer rate in bytes per second.  0 (the default) means no limit.
'  Throttling is useful to avoid saturating a shared link.
ftp.BandwidthThrottleDown = 1048576
ftp.BandwidthThrottleUp = 524288

'  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
    Log(ftp.LastErrorText)
    Return
End If


success = ftp.GetFile("public_html/bigfile.zip", "qa_output/bigfile.zip")
If success = False Then
    Log(ftp.LastErrorText)
    Return
End If


'  The current average rates are updated during transfers.
Log("Download rate: " & ftp.DownloadTransferRate & " bytes/sec")
Log("Upload rate: " & ftp.UploadTransferRate & " bytes/sec")

success = ftp.Disconnect
If success = False Then
    Log(ftp.LastErrorText)
    Return
End If