July 30, 2023

tFlowMeterCatcher – Docs for ESB 7.x


Operates as a log function triggered by the use of a tFlowMeter component in the Job.

Based on a defined schema, the tFlowMeterCatcher catches the processing volumetric
from the tFlowMeter component and
passes them on to the output component.

tFlowMeterCatcher Standard properties

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

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

The component in this framework is available in all Talend

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. In this particular
case, the schema is read-only, as this component gathers standard
log information including:


Moment: Processing time and date


Pid: Process ID


Father_pid: Process ID of the
father Job if applicable. If not applicable, Pid is


Root_pid: Process ID of the root
Job if applicable. If not applicable, pid of current Job is


System_pid: Process id generated
by the system


Project: Project name, the Job
belongs to.


Job: Name of the current


Job_repository_id: ID generated
by the application.


Job_version: Version number of
the current Job


Context: Name of the current


Origin: Name of the component if


Label: Label of the row
connection preceding the tFlowMeter
component in the Job, and that will be analyzed for


Count: Actual number of rows
being processed


Reference: Number of rows passing
the reference link.


Thresholds: Only used when the
relative mode is selected in the tFlowMeter component.

Global Variables

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.


Usage rule

This component is the start component of a secondary Job which
triggers automatically at the end of the main Job.


The use of this component cannot be separated from the use of the
tFlowMeter. For more
information, see tFlowMeter

Catching flow metrics from a Job

The following basic Job aims at catching the number of rows being passed in
the flow processed. The measures are taken twice, once after the input component, that
is, before the filtering step and once right after the filtering step, that is, before
the output component.

  • Drop the following components from the Palette to the design workspace: tMysqlInput, tFlowMeter
    (x2), tMap, tLogRow, tFlowMeterCatcher and tFileOutputDelimited.

  • Link components using row main connections and click on the label
    to give consistent name throughout the Job, such as US_States from the input component and filtered_states for the output from the tMap component, for example.

  • Link the tFlowMeterCatcher
    to the tFileOutputDelimited component
    using a row main link also as data is passed.

  • On the tMysqlInput Component
    view, configure the connection properties as Repository, if the table metadata are stored in the Repository.
    Or else, set the Type as Built-in and
    configure manually the connection and schema details if they are built-in for
    this Job.

  • The 50 States of the USA are recorded in the table states. In order for all 50 entries of the table to get
    selected, the query to run onto the Mysql database is as follows:

    select * from states.

  • Select the relevant encoding
    on the Advanced settings vertical tab.

  • Then select the following component which is a tFlowMeter and set its properties.

  • Select the check box Use input
    connection name as label
    , in order to reuse the label you chose
    in the log output file (tFileOutputDelimited).

  • The mode is Absolute as
    there is no reference flow to meter against, also no Threshold is to be set for this example.


The Thresholds information is
of use within a supervising tool such as
Talend Activity Monitoring Console
in order to get a proportional representation of the flow process. See
Talend Activity Monitoring Console User guide
for more

  • Then launch the tMap
    editor to set the filtering properties.

  • For this use case, drag and drop the ID and State columns from
    the Input area of the tMap towards the
    Output area. No variable is used in this example.

  • On the Output flow area (labelled filtered_states in this example), click the arrow & plus button to
    activate the expression filter field.

  • Drag the State column from the Input area
    (row2) towards the expression filter field and type
    in the rest of the expression in order to filter the state labels starting with
    the letter M. The final expression looks like: row2.State.startsWith("M")

  • Click OK to validate the

  • Then select the second tFlowMeter component and set its properties.

  • Select the check box Use input
    connection name as label

  • Select Relative as
    Mode and in the Reference connections list, select US_States as reference to be measured against.

  • Once again, no threshold is used for this use case.

  • No particular setting is required in the tLogRow.

  • Neither does the tFlowMeterCatcher as this component’s properties are limited to
    a preset schema which includes typical log information.

  • So eventually set the log output component (tFileOutputDelimited).

  • Select the Append check
    box in order to log all tFlowMeter

  • Then save your Job and press F6 to execute it.


The Run view shows the filtered
state labels as defined in the Job.


In the delimited csv file, the number of rows shown in column count varies between tFlowMeter1 and tFlowMeter2 as
the filtering has then been carried out. The reference column
shows also this difference.

Document get from Talend https://help.talend.com
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