SQL Server

Start Concurrent SSH Commands with QuickCmdSend

Demonstrates the Chilkat Ssh.QuickCmdSend method, which starts a remote command and immediately returns its channel number. The only argument is the command line. Internally it opens a session channel and sends an exec request.

Background: Because it returns without waiting, several commands can run concurrently over one authenticated connection — far faster than running them one after another when each has latency or slow work to do. Pair it with QuickCmdCheck, which reports commands as they finish, so results can be collected in completion order rather than the order they were started.

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-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  Demonstrates the Ssh.QuickCmdSend method, which starts a remote command and immediately
    --  returns its channel number.  The only argument is the command line.  Because it returns
    --  right away, several commands can run concurrently on the same SSH connection.

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

    DECLARE @sshPort int
    SELECT @sshPort = 22
    EXEC sp_OAMethod @ssh, 'Connect', @success OUT, 'ssh.example.com', @sshPort
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        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.
    DECLARE @password nvarchar(4000)
    SELECT @password = 'mySshPassword'

    EXEC sp_OAMethod @ssh, 'AuthenticatePw', @success OUT, 'mySshLogin', @password
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  Start three commands without waiting for any of them to finish.
    DECLARE @channel1 int
    EXEC sp_OAMethod @ssh, 'QuickCmdSend', @channel1 OUT, 'sleep 2; echo first done'
    IF @channel1 < 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    DECLARE @channel2 int
    EXEC sp_OAMethod @ssh, 'QuickCmdSend', @channel2 OUT, 'echo second done'
    IF @channel2 < 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    DECLARE @channel3 int
    EXEC sp_OAMethod @ssh, 'QuickCmdSend', @channel3 OUT, 'sleep 1; echo third done'
    IF @channel3 < 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END


    PRINT 'Started three concurrent commands.'

    --  Use QuickCmdCheck to collect the results as each command completes.

    EXEC sp_OAMethod @ssh, 'Disconnect', NULL

    EXEC @hr = sp_OADestroy @ssh


END
GO