# tLogCatcher

Operates as a log function triggered by one of the three: Java exception, tDie or tWarn, to collect and transfer log data.

Both the tDie and tWarn components are closely related to the tLogCatcher component.They generally make sense when used alongside a tLogCatcher component in order for the log data collected to be encapsulated and passed on to the output defined.

Fetches set fields and messages from Java Exception, tDie and/or tWarn and passes them on to the next component.

## tLogCatcher Standard properties

These properties are used to configure tLogCatcher running in the Standard Job framework.

The Standard tLogCatcher component belongs to the Logs & Errors family.

The component in this framework is available in all Talend products.

## Basic settings

| Properties | Description |
| --- | --- |
| Schema and Edit<br>Schema | A schema is a row description, it defines the fields to be processed<br>and passed on to the next component.<br><br>The schema of this component is read-only. It describes the properties<br>of the log data. You can click the [...] button next to Edit<br>schema to view the predefined schema which contains the<br>following fields:<br><br><ul> <li> <p> <span>moment</span>: the time when the                                    message is caught.</p> </li> <li> <p> <span>pid</span>: the process ID of the                                    Job.</p> </li> <li> <p> <span>root_pid</span>: the root process                                    ID.</p> </li> <li> <p> <span>father_pid</span>: the father                                    process ID.</p> </li> <li> <p> <span>project</span>: the name of the                                    project.</p> </li> <li> <p> <span>job</span>: the name of the                                    Job.</p> </li> <li> <p> <span>context</span>: the context used to                                    run the Job.</p> </li> <li> <p> <span>priority</span>: the priority level                                    of the message.</p> </li> <li> <p> <span>type</span>: the type of the                                    message.</p> </li> <li> <p> <span>origin</span>: the name of the                                    component that triggers the message.</p> </li> <li> <p> <span>message</span>: the message                                    content.</p> </li> <li> <p> <span>code</span>: the error code                                    level.</p> </li> </ul> |
| Catch Java Exception | Select this check box to trigger the tCatch function when a Java Exception occurs in the<br>Job. |
| Catch tDie | Select this check box to trigger the tCatch function when a tDie component is called in a Job. |
| Catch tWarn | Select this check box to trigger the tCatch function when a tWarn component is called in a Job. |

## Global Variables

| Variables | Description |
| --- | --- |
| Global Variables | ERROR\_MESSAGE: the error message generated by the<br>component when an error occurs. This is an After variable and it returns a string. This<br>variable functions only if the Die on error checkbox is<br>cleared, if the component has this checkbox.<br><br>A Flow variable functions during the execution of a component<br>while an After variable functions after the execution of the component.<br><br>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<br>it.<br><br>For more information about variables, see [Using contexts and variables](https://help.qlik.com/talend/r/en-US/8.0/studio-user-guide/contexts-and-variables). |

## Usage

| Usage guidance | Description |
| --- | --- |
| **Usage rule** | This component is usually used as the start component of a secondary<br>Job which is automatically triggered at the end of the main Job. |

**Related concepts**

* [Catching messages triggered by a tWarn component](https://help.qlik.com/talend/en-US/components/8.0/logs-and-errors/twarn-tlogcatcher-tlogrow-trowgenerator-catching-messages-triggered-by-twarn-component-standard-component "This example shows you how to use the tLogCatcher component to catch the messages triggered by a tWarn component.")
* [Catching the message triggered by a tDie component](https://help.qlik.com/talend/en-US/components/8.0/logs-and-errors/tdie-tlogcatcher-tjava-catching-message-triggered-by-tdie-component-standard-component "This example shows you how to use the tLogCatcher component to catch the message triggered by a tDie component.")