July 30, 2023

tWaitForFile – Docs for ESB 7.x

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tWaitForFile

Iterates on a directory and triggers the next component when the defined condition
is met.

This component is used to put the component connected
with it in waiting state. It then triggers that component when the defined file operation
occurs in the specified directory.

tWaitForFile Standard properties

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

The Standard
tWaitForFile component belongs to the Orchestration family.

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

Basic settings

Time (in seconds)
between iterations

Set the time interval in seconds between each two
iterations.

Max. number of iterations (infinite loop if
empty)

Set the maximum number of iterations on the specified
directory.

Directory to scan

Specify the directory to iterate on.

File mask

Type in the file mask to filter the files to be monitored. To
monitor a given file, type in the file name.

Include subdirectories

Select this check box to iterate also on the
subdirectories.

Case sensitive

Select this check box to activate case sensitivity.

Include present file

Select this check box to include the file in use.

Trigger action when

Select one of the following trigger conditions:

a file is created: triggers the
next component when a file is created.

a file is deleted: triggers the
next component when a file is removed.

a file is updated: triggers the
next component when a file is modified.

a file is created or updated or
deleted: triggers the next component when a file is
created, or removed, or modified.

Then

Select what to do with the iteration loop after the next component
is triggered:

continue loop: continues
iterating until the number of iterations reaches the defined maximum
value.

exit loop: stops iterating
immediately.

Schema and Edit
Schema

A schema is a row description, it defines the number of fields
that will be processed and passed on to the next component. The
schema of this component is Built-in and cannot be updated.

Advanced Settings

Wait for file to be released Every (in
ms)

Select this check box so that the next component is triggered only
after the file operation is completed.

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.

CURRENT_ITERATION: the sequence number of the current
iteration. This is a Flow variable and it returns an integer.

PRESENT_FILE: the path and name of the present file. This
is a Flow variable and it returns a string.

DELETED_FILE: the path and name of the deleted file. This
is a Flow variable and it returns a string.

CREATED_FILE: the path and name of the created file. This
is a Flow variable and it returns a string.

UPDATED_FILE: the path and name of the updated file. This
is a Flow variable and it returns a string.

FILENAME: the name of the file being processed. This is a
Flow variable and it returns a string.

NOT_UPDATED_FILE: the path and name of the file that has
not been updated. This is a Flow variable and it returns a string.

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.

Usage

Usage rule

This component plays the role of triggering the next component
based on the defined condition. Therefore this component requires
another component to be connected to it via a link.

Connections

Outgoing links (from this component to another):

Row: Main; Iterate.

Trigger: On Subjob Ok; Run if; On
Component Ok; On Component Error.

Incoming links (from one component to this one):

Row: Iterate.

Trigger: On Subjob Ok; Run if; On
Component Ok; On Component Error; Synchronize; Parallelize.

For further information regarding connections, see

Talend Studio User
Guide.

Waiting for a file to be created and stopping the iteration loop after a
message is triggered

This scenario describes a Job that scans a directory and triggers a message showing
file creation information on the console when a text file is created in that directory.
Immediately after this, the scanning is ended, followed by another message showing the
number of iterations finished.

tWaitForFile_1.png

Dropping and linking the components

  1. Drop three components from the Palette
    onto the design workspace: one tWaitForFile
    and two tJava components.
  2. Connect tWaitForFile to the first
    tJava using a Row > Iterate
    connection.
  3. Connect tWaitForFile to the second
    tJava using a Trigger > On Subjob Ok
    connection.

Configuring the components

  1. Double-click tWaitForFile to open its
    Basic settings view.

    tWaitForFile_2.png

  2. In the Directory to scan field, enter the
    directory to be scanned.
  3. In the File mask field, enter “*.txt” to scan only text files.
  4. From the Trigger action when drop-down
    list, select a file is created to trigger
    the first tJava when a text file is
    created.
  5. From the Then drop-down list, select
    exit loop to stop the iteration loop
    immediately after the first tJava is
    triggered.
  6. Double-click the first tJava to open its
    Basic settings view.

    tWaitForFile_3.png

  7. In the code area, type in the following
    code:System.out.println("A file was created at " + TalendDate.getCurrentDate());
    System.out.println("Name of the created file: " + ((String)globalMap.get("tWaitForFile_1_CREATED_FILE")));
  8. Double-click the second tJava to open its
    Basic settings view.
  9. In the code area, type in the following
    code:System.out.println("
    Iteration loop ended at " + TalendDate.getCurrentDate());
    System.out.println("Number of iterations finished: " + ((Integer)globalMap.get("tWaitForFile_1_CURRENT_ITERATION")));

Saving and executing the Job

  1. Press Ctrl+S to save the Job.
  2. Press F6 to execute the Job.
  3. Create a text file exit.txt in the
    defined directory.

    tWaitForFile_4.png

    When a text file is created, a message about file creation is displayed on
    the Run console. The iteration loop is
    ended immediately after that, followed by another message showing the time
    the iteration loop is ended and the number of iterations executed.

Waiting for a file to be created and continuing the iteration loop after
a message is triggered

Based on the previous scenario, this scenario describes a Job triggers a message on
the console when a text file is created in the directory being scanned, without ending
the scanning process immediately. The Job continues scanning the directory until the
number of iterations reaches the defined maximum value.

Procedure

  1. Double-click tWaitForFile to open its
    Basic settings view.

    tWaitForFile_5.png

  2. In the Time (in seconds) between iterations
    field, enter the time interval in seconds between each two iterations. In this
    example, it is set to 5.
  3. In the Max. number of iterations (infinite loop if
    empty)     field, enter the maximum number of iterations. In this
    example, it is set to 10.
  4. From the Then drop-down list, select
    continue loop to continue the iteration
    loop after the message is triggered.
  5. Press Ctrl+S to save the Job.
  6. Press F6 to execute the Job.
  7. Create a text file continue.txt in the
    defined directory.

    tWaitForFile_6.png

    When a text file is created, a message about file creation is displayed on the
    Run console. The iteration loop is ended
    until the number of iterations reaches ten, followed by another message showing
    the time the iteration loop is ended and the number of iterations
    executed.
Document get from Talend https://help.talend.com
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Docs 7.x
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