Visual FoxPro

Resume an Interrupted FTP Transfer

Demonstrates the RestartNext and PartialTransfer properties, which request that the next transfer resume from existing content and report whether a download was incomplete.

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: For a large transfer over a flaky link, restarting from zero after a drop is wasteful. Setting RestartNext makes the next download continue from the current local file size (and the next upload from the remote size); the flag is consumed by that one transfer and then reset. Afterward PartialTransfer tells you whether the download got only part of the file — the signal to set RestartNext again and resume once more.

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Visual FoxPro

LOCAL lnSuccess
LOCAL loFtp

lnSuccess = 0

loFtp = CreateObject('Chilkat.Ftp2')

loFtp.Hostname = "ftp.example.com"
loFtp.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.
loFtp.Password = "myPassword"

lnSuccess = loFtp.Connect()
IF (lnSuccess = 0) THEN
    ? loFtp.LastErrorText
    RELEASE loFtp
    CANCEL
ENDIF

*  RestartNext requests that the NEXT transfer resume from existing content rather than starting
*  over.  It is consumed by that transfer and then automatically reset.
loFtp.RestartNext = 1

*  Resume a partially-downloaded file.  Because RestartNext is set, the download continues from
*  the current local file size.
lnSuccess = loFtp.GetFile("public_html/bigfile.zip","qa_output/bigfile.zip")
IF (lnSuccess = 0) THEN
    ? loFtp.LastErrorText
    RELEASE loFtp
    CANCEL
ENDIF

*  PartialTransfer indicates whether the most recent download received some, but not all, of the
*  remote file -- distinguishing a mid-transfer failure from other outcomes.
IF (loFtp.PartialTransfer) THEN
    ? "Only part of the file was received; another resume may be needed."
ELSE
    ? "The file was fully received."
ENDIF

lnSuccess = loFtp.Disconnect()
IF (lnSuccess = 0) THEN
    ? loFtp.LastErrorText
    RELEASE loFtp
    CANCEL
ENDIF

RELEASE loFtp