tBufferOutput

tBufferOutput properties

Component family	Misc
Function	This component collects data in a buffer in order to access it later via webservice for example.
Purpose	This component allows a Webservice to access data. Indeed it had 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.
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. Since version 5.6, both the Built-In mode and the Repository mode are available in any of the Talend solutions. 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	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	This component is not startable (green background) and it requires an output component.

Scenario 1: 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 Scenario 2: Buffering output data on the webapp server.

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.

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.

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.

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.

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:

Scenario 2: 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

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

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:

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.
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.

Configuring the input data

In the design workspace, select tFixedFlowInput.
Click the Component
tab to define the basic settings for tFixedFlowInput.
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.
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.
Click in the Value
cell of each of the first two defined columns and
press Ctrl+Space to
access the global variable list.
From the global variable list, select
TalendDate.getCurrentDate()
and
talendDatagenerator.getFirstName,
for the now and
firstname columns
respectively.
Click in the Value
cell of lastname column and
press Ctrl+Space to
access the global variable list.
From the global variable list, select
context.lastname, the context
variable you created for the last name column.

Building your Job as a Webservice

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

In the Repository
tree view, right-click on the above created Job and
select Build Job.
The [Build Job]
dialog box appears.
Click the Browse…
button to select a directory to archive your Job
in.
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.
Copy the War folder and paste it in a Tomcat webapp
directory.

Scenario 3: Calling a Job with context variables from a browser

This scenario describes how to call the Job you created in Scenario 2: 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.

Click Enter to execute your Job from your
browser.

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.

The Job generates two lines with MASSY as last name.

Scenario 4: 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 Scenario 2: 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.

In the design workspace, select tWebServiceInput.
Click the Component tab to
define the basic settings for tWebServiceInput.

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.

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.

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.

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 5.x

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tBufferOutput – Docs for ESB 5.x