DataFlex

SSH Parallel Remote Commands on a Single Server

Demonstrates running several commands in parallel on one SSH server and collecting each command's output as it finishes. QuickCmdSend starts each command and returns immediately; QuickCmdCheck reports them as they complete.

Background: Because SSH multiplexes channels, several commands can run at once over one authenticated connection — far faster than running them one after another when each involves waiting. Results arrive in completion order rather than the order the commands were started, so the loop keys off the returned channel number. Distinguish the two negative returns carefully: -1 means "still working, ask again," while -2 means nothing remains to collect or the connection failed.

Chilkat DataFlex Downloads

Download Chilkat for DataFlex

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSsh
    Integer iPort
    String sPassword
    Integer iChannel1
    Integer iChannel2
    Integer iChannel3
    Integer iPollTimeoutMs
    Integer iNumFinished
    Integer iChannel
    String sCmdOutput
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    //  Demonstrates running several commands in parallel on a single SSH server and collecting each
    //  command's output as it finishes.

    Get Create (RefClass(cComChilkatSsh)) To hoSsh
    If (Not(IsComObjectCreated(hoSsh))) Begin
        Send CreateComObject of hoSsh
    End

    Move 22 To iPort
    Get ComConnect Of hoSsh "ssh.example.com" iPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  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.
    Move "mySshPassword" To sPassword

    Get ComAuthenticatePw Of hoSsh "mySshLogin" sPassword To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  QuickCmdSend starts a command and returns immediately, so all three run concurrently, each on
    //  its own session channel.
    Get ComQuickCmdSend Of hoSsh "df" To iChannel1
    If (iChannel1 < 0) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComQuickCmdSend Of hoSsh "date" To iChannel2
    If (iChannel2 < 0) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComQuickCmdSend Of hoSsh "echo hello world" To iChannel3
    If (iChannel3 < 0) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Collect the results.  QuickCmdCheck returns the channel number of a completed command,
    //  -1 when commands are still pending but none finished within the timeout, or -2 when nothing
    //  remains to be checked (or an error occurred).
    Move 50 To iPollTimeoutMs
    Move 0 To iNumFinished
    While (iNumFinished < 3)
        Get ComQuickCmdCheck Of hoSsh iPollTimeoutMs To iChannel
        If (iChannel = -2) Begin
            Get ComLastErrorText Of hoSsh To sTemp1
            Showln sTemp1
            Procedure_Return
        End

        If (iChannel >= 0) Begin
            Showln "---- channel " iChannel " finished ----"
            Get ComGetReceivedText Of hoSsh iChannel "utf-8" To sCmdOutput
            Get ComLastMethodSuccess Of hoSsh To bTemp1
            If (bTemp1 = False) Begin
                Get ComLastErrorText Of hoSsh To sTemp1
                Showln sTemp1
                Procedure_Return
            End

            Showln sCmdOutput
            Move (iNumFinished + 1) To iNumFinished
        End

    Loop

    Send ComDisconnect To hoSsh


End_Procedure