July 30, 2023

tBufferOutput – Docs for ESB 7.x

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tBufferOutput

Collects data in a buffer in order to access it later via webservice for
example.

tBufferOutput has been designed to be exported as Webservice in order to
access data on the web application server directly. For more information, see Talend Studio User Guide.

tBufferOutput Standard properties

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

The Standard
tBufferOutput component belongs to the Misc family.

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

Basic settings

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 is
either built-in or remote in the Repository.

Click Edit
schema to make changes to the schema. If the current schema is of the Repository type, three options are available:

  • View schema: choose this
    option to view the schema only.

  • Change to built-in property:
    choose this option to change the schema to Built-in for local changes.

  • Update repository connection:
    choose this option to change the schema stored in the repository and decide whether
    to propagate the changes to all the Jobs upon completion. If you just want to
    propagate the changes to the current Job, you can select No upon completion and choose this schema metadata
    again in the Repository Content
    window.

In the case of the tBufferOutput, the column position is
more important than the column label as this will
be taken into account.

 

Built-in:
The schema will be created and stored locally for
this component only. Related topic: see

Talend Studio User Guide.

 

Repository:
The schema already exists and is stored in the
Repository, hence can be reused in various
projects and Job designs. Related topic: see

Talend Studio User Guide.

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 +
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 is not startable (green
background) and it requires an output
component.

Buffering data

This scenario describes an intentionally basic Job that bufferizes data in a
child job while a parent Job simply displays the bufferized data onto the
standard output console. For an example of how to use tBufferOutput to access output data directly on the Web
application server, see Buffering output data on the webapp server.

tBufferOutput_1.png

  • Create two Jobs: a first Job
    (BufferFatherJob) runs the
    second Job and displays its content onto the Run console. The second Job
    (BufferChildJob) stores the
    defined data into a buffer memory.

  • On the first Job, drop the following components: tRunJob and tLogRow from the Palette to the design
    workspace.

  • On the second Job, drop the following components: tFileInputDelimited and
    tBufferOutput the
    same way.

Let’s set the parameters of the second Job first:

  • Select the tFileInputDelimited and on the Basic Settings tab of the
    Component view, set
    the access parameters to the input file.

tBufferOutput_2.png

  • In File Name, browse to the
    delimited file whose data are to be bufferized.

  • Define the Row and Field separators, as well as
    the Header.

tBufferOutput_3.png

  • Describe the Schema of the
    data to be passed on to the tBufferOutput component.

  • Select the tBufferOutput
    component and set the parameters on the Basic Settings tab of the
    Component view.

tBufferOutput_4.png

  • Generally the schema is propagated from the input component
    and automatically fed into the tBufferOutput schema. But you could also
    set part of the schema to be bufferized if you want
    to.

  • Now on the other Job (BufferFatherJob)
    Design, define the parameters of the tRunJob component.

tBufferOutput_5.png

  • Edit the Schema if relevant and select the column to be
    displayed. The schema can be identical to the bufferized
    schema or different.

  • You could also define context parameters to be used for this
    particular execution. To keep it simple, the default context
    with no particular setting is used for this use case.

Press F6 to execute the parent Job. The
tRunJob looks after executing the
child Job and returns the data onto the standard console:

tBufferOutput_6.png

Buffering data to be used as a source system

This scenario describes a Job that buffers data to be used as a source system by MDM.

An MDM process will invoke this Job to retrieve data by looking up the defined elements
(agent region values) from the buffered data. The process can then display the retrieved data
in the Talend MDM Web User Interface without really saving them in the MDM hub.

Creating a data buffer Job

  1. Create a Job named DetermineRegion.
  2. Drop the following components from the Palette onto the design workspace: tJava, tFixedFlowInput, and
    tBufferOutput.
  3. Connect tJava to
    tFixedFlowInput using a Trigger > On Component
    Ok     link.
  4. Connect tFixedFlowInput to
    tBufferOutput using a Row > Main link.

    tBufferOutput_7.png

Configuring the Job to buffer data

  1. In the Contexts view, add a new context variable with
    the Name of xmlInput and the
    Type of String.

    In this example, the context variable xmlInput of
    the Job will be specified in the MDM process which wants to invoke this
    Job.

    You can search for further information about MDM
    processess on Talend Help Center (https://help.talend.com).

    If you cannot find the Contexts view, go to Window > Show view > Talend, and select Contexts.

    For more information about how to define context variables, see Talend Studio
    User Guide.

    You can search for further information about how to
    define context variables on Talend Help Center (https://help.talend.com).

  2. Double-click the tJava component to open
    its Component view, and in the
    Code area, enter the code according to your
    needs.

    In this example, enter
    System.out.println("#############################"+context.xmlInput);.
  3. Double-click the tFixedFlowInput component to open its
    Component view.
  4. Click the […] button next
    to Edit schema to open the dialog box and
    define the schema for the data to be used by the source system.

    In this example, add one new column col0 of the type
    String.
  5. After the schema is defined, click Yes in the
    Propagate dialog box to propagate the schema changes
    to the following component tBufferOutput.
  6. In the Number of rows field, enter
    1.
  7. In the Mode area, select Use Single
    Table     and enter "Paris" in the
    Value column that corresponds to the column
    col0 you have defined.

    In this example, the value of the col0 provides the
    agent region information to be retrieved by MDM.
  8. Double-click the tBufferOutput component to open its
    Component view, and then make sure its schema is
    synchronized with the previous component
    tFixedFlowInput.
  9. Run the Job and make sure the execution succeeds.

Buffering output data on the webapp server

This scenario describes a Job that is called as a Webservice and stores the
output data in a buffer directly on the server of the Web application. This scenario creates
first a Webservice oriented Job with context variables, and next exports the Job as a
Webservice.

Creating a Job

  1. Drop the following components from the Palette onto the design
    workspace: tFixedFlowInput and tBufferOutput.
  2. Connect tFixedFlowInput to tBufferOutput using a
    Row Main
    link.

    tBufferOutput_8.png

Creating a context variable

For this scenario, you will define two context variables:
nb_lines and
lastname. The first variable will set
the number of lines the tFixedFlowInput
component will generate, and the second one will set the
last name to display in the output list. For more information about
how to create and use context variables, see
Talend Studio User Guide.

To define the two context variables:

  1. Select the Contexts
    tab view of your Job, and click the [+] button at the bottom of
    the view to add two variables, respectively
    nb_lines of
    type Integer and
    lastname of
    type String.
  2. In the Value field
    for the variables, set the last name to be displayed
    and the number of lines to be generated,
    respectively Ford
    and 3 in this
    example.

    tBufferOutput_9.png

Configuring the input data

  1. In the design workspace, select tFixedFlowInput.
  2. Click the Component
    tab to define the basic settings for tFixedFlowInput.
  3. Click the three-dot […] button next to Edit Schema to describe the
    data structure you want to create from internal
    variables. In this scenario, the schema is made of
    three columns, now of type
    Date,
    firstname of type String, and
    lastname of type String.

    tBufferOutput_10.png

  4. Click OK to close the
    dialog box and accept propagating the changes when
    prompted by the system. The three defined columns
    display in the Values panel of the Basic settings view of
    tFixedFlowInput.

    tBufferOutput_11.png

  5. Click in the Value
    cell of each of the first two defined columns and
    press Ctrl+Space to
    access the global variable list.
  6. From the global variable list, select

    Talend Date.getCurrentDate()
    and
    talendDatagenerator.getFirstName,
    for the now and
    firstname columns
    respectively.
  7. Click in the Value
    cell of lastname column and
    press Ctrl+Space to
    access the global variable list.
  8. From the global variable list, select
    context.lastname, the context
    variable you created for the last name column.

    tBufferOutput_12.png

Building your Job as a Webservice

Before building your Job as a Web service, see
Talend Studio User Guide for more
information.

  1. In the Repository
    tree view, right-click on the above created Job and
    select Build Job.
    The Build Job
    dialog box appears.

    tBufferOutput_13.png

  2. Click the Browse…
    button to select a directory to archive your Job
    in.
  3. In the Build type
    panel, select the build type you want to use in the
    Tomcat webapp directory (WAR in this example) and
    click Finish. The
    Build Job
    dialog box disappears.
  4. Copy the War folder and paste it in a Tomcat webapp
    directory.

Calling a Job with context variables from a browser

This scenario describes how to call the Job you created in Buffering output data on the webapp server from your browser with/without modifying the
values of the context variables.

Type the following URL into your browser: http://localhost:8080//export_job/services/export_job3?method=runJob
where “export_job” is the name of the webapp directory deployed in Tomcat
and “export_job3” is the name of the Job.

tBufferOutput_14.png

Click Enter to execute your Job from your
browser.

tBufferOutput_15.png

The Job uses the default values of the context variables:
nb_lines and lastname,
that is it generates three lines with the current date, first name and Ford
as a last name.

You can modify the values of the context variables directly from your browser.
To call the Job from your browser and modify the values of the two context
variables, type the following URL:

http://localhost:8080//export_job/services/export_job3?method=runJob&arg1=–context_param%20lastname=MASSY&arg2=–context_param%20nb_lines=2.

%20 stands for a blank space in the URL language. In the first argument
“arg1”, you set the value of the context variable to display “MASSY” as last
name. In the second argument “arg2”, you set the value of the context
variable to “2” to generate only two lines.

Click Enter to execute your Job from your
browser.

tBufferOutput_16.png

The Job generates two lines with MASSY as last name.

Calling a Job exported as Webservice in another Job

This scenario describes a Job that calls another Job exported as a
Webservice using the tWebServiceInput.
This scenario will call the Job created in Buffering output data on the webapp server.

  • Drop the following components from the Palette onto the design
    workspace: tWebServiceInput and tLogRow.

  • Connect tWebserviceInput to tLogRow using a
    Row Main
    link.

tBufferOutput_17.png

  • In the design workspace, select tWebServiceInput.

  • Click the Component tab to define the basic
    settings for tWebServiceInput.

tBufferOutput_18.png

  • Set the Schema
    Type     to Built-In and click the three-dot
    […] button
    next to Edit Schema
    to describe the data structure you want to call
    from the exported Job. In this scenario, the schema is made
    of three columns, now, firstname, and lastname.

tBufferOutput_19.png

  • Click the plus button to add the three parameter
    lines and define your variables. Click OK to close the dialog
    box.

  • In the WSDL field of the Basic settings view of
    tWebServiceInput, enter the URL http://localhost:8080/export_job/services/export_job3?WSDL
    where “export_job” is the name od the webapp directory where
    the Job to call is stored and “export_job3” is the name of
    the Job itself.

tBufferOutput_20.png

  • In the Method name
    field, enter runJob.

  • In the Parameters panel, Click the plus button
    to add two parameter lines to define your context
    variables.

  • Click in the first Value cell to enter the parameter to
    set the number of generated lines using the following
    syntax: –context_param nb_line=3.

  • Click in the second Value cell to enter the parameter to
    set the last name to display using the following syntax: –context_param lastname=Ford.

  • Select tLogRow and click the Component tab to display
    the component view.

  • Set the Basic settings
    for the tLogRow
    component to display the output data in a
    tabular mode. For more information, see tLogRow.

  • Save your Job and press F6 to execute it.

tBufferOutput_21.png

The system generates three columns with the current date, first
name, and last name and displays them onto the log console in a tabular
mode.

Document get from Talend https://help.talend.com
Thank you for watching.
Docs 7.x
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