tServerAlive validates the status of the connection to a specified host.
tServerAlive helps you check whether the connection to a specified host is up or down, which is indicated by the boolean value returned by the global variable SERVER_ALIVE_RESULT.
Select either Ping or Telnet from the drop-down list of protocols.
IP address or host name of the remote server to be checked.
Timeout Interval (in seconds)
Enter the timeout interval in seconds. If the target host is reached within this time, the component's global variable SERVER_ALIVE_RESULT will be set to true, otherwise false.
Listening port number of the Telnet server.
Available when Telnet is selected from the Protocol drop-down list.
Select this check box to gather the Job processing metadata at a Job level as well as at each component level.
SERVER_ALIVE_RESULT: the status of the connection to a remote host. This is an After variable and it returns a boolean.
ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box.
A Flow variable functions during the execution of a component while an After variable functions after the execution of the component.
To fill up a field or expression with a variable, press Ctrl + Space to access the variable list and choose the variable to use from it.
For further information about variables, see Talend Studio User Guide.
This component is generally used as a one-component subjob.
In this scenario, tServerAlive is used to ping a remote host and the value of its global variable SERVER_ALIVE_RESULT is extracted to show the connection status.
Drop the following components from the Palette onto the design workspace: tServerAlive, tFixedFlowInput, and tLogRow.
Connect tServerAlive to tFixedFlowInput using a Trigger > On Subjob Ok connection.
Connect tFixedFlowInput to tLogRow using a Row > Main connection.
Double-click tServerAlive to open its Basic settings view.
In the Protocol drop-down list, select Ping.
In the Host field, enter the IP address of the remote server to ping.
In the Timeout Interval field, enter the timeout interval in seconds.
Double-click tFixedFlowInput to open its Basic settings view.
Click the [...] button next to Edit schema to open the schema editor.
Click the [+] button to add one column, namely status, of the boolean type.
Click OK to validate the schema and close the editor.
In the dialog box that appears, click Yes to propagate the changes to the subsequent component.
In the Values table, press the Ctrl + Space keys in the Value field to select tServerAlive_1_SERVER_ALIVE_RESULT from the variable list.
Double-click tLogRow to open its Basic settings view.
Select Table (print values in cells of a table) for a better display of the results.