SQL Server

Monitor, Cancel, and Keep-Alive Long FTP Transfers

Demonstrates the HeartbeatMs, AbortCurrent, and LargeFileMeasures properties, which monitor long operations, allow cancellation, and keep the control connection alive during long transfers.

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: A large transfer blocks for a long time, and these properties make that manageable. HeartbeatMs fires a periodic AbortCheck callback so an application can show progress and remain responsive, and AbortCurrent — set from that callback or another thread — cancels the running operation. LargeFileMeasures addresses a subtler problem: while data flows on the data connection, an idle control connection can be dropped by a firewall, so this sends a periodic NOOP to keep it alive.

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SQL Server

--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    DECLARE @ftp int
    EXEC @hr = sp_OACreate 'Chilkat.Ftp2', @ftp OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    EXEC sp_OASetProperty @ftp, 'Hostname', 'ftp.example.com'
    EXEC sp_OASetProperty @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.
    EXEC sp_OASetProperty @ftp, 'Password', 'myPassword'

    --  HeartbeatMs sets how often the AbortCheck event fires during long operations.  The default 0
    --  disables it.  A nonzero value lets an application monitor progress and request cancellation.
    EXEC sp_OASetProperty @ftp, 'HeartbeatMs', 100

    --  AbortCurrent may be set to 1 (typically from another thread, or from an AbortCheck
    --  callback) to cancel a running operation.  Left 0 here so nothing is pre-emptively aborted.
    EXEC sp_OASetProperty @ftp, 'AbortCurrent', 0

    --  LargeFileMeasures (default 0) sends a NOOP on the control channel once per minute during
    --  a long transfer, keeping the control connection alive while data flows.
    EXEC sp_OASetProperty @ftp, 'LargeFileMeasures', 1

    EXEC sp_OAMethod @ftp, 'Connect', @success OUT
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ftp
        RETURN
      END

    EXEC sp_OAMethod @ftp, 'GetFile', @success OUT, 'public_html/hugefile.iso', 'qa_output/hugefile.iso'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ftp
        RETURN
      END

    PRINT 'Transfer complete.'

    EXEC sp_OAMethod @ftp, 'Disconnect', @success OUT
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ftp
        RETURN
      END

    EXEC @hr = sp_OADestroy @ftp


END
GO