DataFlex

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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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSsh
    Integer iPort
    Boolean iConnected
    String sTemp1

    Move False To iSuccess

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

    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

    //  IsConnected reports the state already known to the Ssh object.  It does not perform a
    //  network round trip.
    Get ComIsConnected Of hoSsh To iConnected
    If (iConnected) 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.
        Get ComSendIgnore Of hoSsh To iConnected
    End

    Showln "connected = " iConnected

    Send ComDisconnect To hoSsh

    //  After disconnecting, the object reports that it is no longer connected.
    Get ComIsConnected Of hoSsh To iConnected
    Showln "connected = " iConnected


End_Procedure