SQL Server

Check the SSH Connection (IsConnected)

Demonstrates how to check whether the connection to the SSH server still exists. The IsConnected property is checked first, and SendIgnore is then used to confirm the link for certain.

Background: These checks differ in strength. IsConnected simply reports the state the object already knows and involves no network activity, so it can stay true after a silent network failure the operating system has not yet noticed. SendIgnore sends an SSH IGNORE message — discarded by the peer by design — which exercises the real write path and is therefore much stronger evidence the link is usable. CheckConnection sits between the two, peeking at the socket without sending anything.

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SQL Server

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

    --  Demonstrates how to check whether the connection to the SSH server still exists.

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

    DECLARE @port int
    SELECT @port = 22
    EXEC sp_OAMethod @ssh, 'Connect', @success OUT, 'ssh.example.com', @port
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  IsConnected reports the state already known to the Ssh object.  It does not perform a
    --  network round trip.
    DECLARE @connected int
    EXEC sp_OAGetProperty @ssh, 'IsConnected', @connected OUT
    IF @connected
      BEGIN
        --  Verify for certain by sending an SSH IGNORE message, which exercises the actual write
        --  path.  The server sends no reply, but a successful send proves the link is writable.
        EXEC sp_OAMethod @ssh, 'SendIgnore', @connected OUT
      END


    PRINT 'connected = ' + @connected

    EXEC sp_OAMethod @ssh, 'Disconnect', NULL

    --  After disconnecting, the object reports that it is no longer connected.
    EXEC sp_OAGetProperty @ssh, 'IsConnected', @connected OUT

    PRINT 'connected = ' + @connected

    EXEC @hr = sp_OADestroy @ssh


END
GO