August 17, 2023

tLogCatcher – Docs for ESB 5.x



tLogCatcher properties

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

Component family

Logs & Errors



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


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

Basic settings

Schema and Edit

A schema is a row description, it defines the fields to be
processed and passed on to the next component.

The schema of this component is read-only.


Catch Java Exception

Select this check box to trigger the tCatch function when a Java Exception occurs in the


Catch tDie

Select this check box to trigger the tCatch function when a tDie is called in a Job


Catch tWarn

Select this check box to trigger the tCatch function when a tWarn is called in a

Global Variables

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 +
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 the start component of a secondary Job which
automatically triggers at the end of the main Job


The activity of this component can be logged using the log4j feature. For more information on this feature, see Talend Studio User

For more information on the log4j logging levels, see the Apache documentation at



Scenario 1: warning & log on entries

In this basic scenario made of three components, a tRowGenerator creates random entries (id to be incremented). The input
hits a tWarn component which triggers the tLogCatcher subjob. This subjob fetches the warning message
as well as standard predefined information and passes them on to the tLogRow for a quick display of the log data.

  • Drop a tRowGenerator, a tWarn, a tLogCatcher and a
    tLogRow from the Palette, on your design workspace

  • Connect the tRowGenerator to the tWarn component.

  • Connect separately the tLogCatcher to the

  • On the tRowGenerator editor, set the random
    entries creation using a basic function:

  • On the tWarn
    Component view, set your warning message, the
    code the priority level. In this case, the message is “this is a

  • For this scenario, we will concatenate a function to the message above, in
    order to collect the first value from the input table.

  • On the Basic settings view of tLogCatcher, select the tWarn check box in order for the message from the latter to be
    collected by the subjob.

  • Click Edit Schema to view the schema used as
    log output. Notice that the log is comprehensive.


Press F6 to execute the Job. Notice that the Log
produced is exhaustive.

Scenario 2: Log & kill a Job

This scenario uses a tLogCatcher and a tDie component. A tRowGenerator is connected to a tFileOutputDelimited using a Row link. On error, the tDie triggers the catcher subjob which displays the log data
content on the Run console.

  • Drop all required components from various folders of the Palette to the design workspace: tRowGenerator, tFileOutputDelimited, tDie,
    tLogCatcher, tLogRow.

  • On the tRowGenerator
    Component view, define the setting of the input
    entries to be handled.

  • Edit the schema and define the following columns as random input examples:
    id, name, quantity, flag and creation.

  • Set the Number of rows onto 0. This will
    constitute the error which the Die operation is based on.

  • On the Values table, define the functions to
    feed the input flow.

  • Define the tFileOutputDelimited to hold the
    possible output data. The row connection from
    the tRowGenerator feeds automatically the
    output schema. The separator is a simple semi-colon.

  • Connect this output component to the tDie
    using a Trigger > If connection.
    Double-click on the newly created connection to define the if:

  • Then double-click to select and define the Basic
    of the tDie

  • Enter your Die message to be transmitted to
    the tLogCatcher before the actual kill-job
    operation happens.

  • Next to the Job but not physically connected to it, drop a tLogCatcher from the Palette to the design workspace and connect it to a tLogRow component.

  • Define the tLogCatcher
    Basic settings. Make sure the tDie box is selected in order to add the Die message
    to the Log information transmitted to the final component.

  • Press F6 to run the Job and notice that the
    log contains a black message and a red one.

  • The black log data come from the tDie and are
    transmitted by the tLogCatcher. In addition the
    normal Java Exception message in red displays as a Job abnormally died.

Document get from Talend
Thank you for watching.
Notify of
Inline Feedbacks
View all comments
Would love your thoughts, please comment.x