August 15, 2023

Scenario: Waiting for insertion of rows in a table – Docs for ESB 6.x

Scenario: Waiting for insertion of rows in a table

This scenario describes a Job reading a DB table and waiting for data to be put in
this table in order for a subjob to be executed. When the condition of the data
insertion in the table is met, then the subjob performs a Select* on the table and
simply displays the content of the inserted data onto the standard console.

Use_Case_tWaitForSqldata1.png
  • Drop the following components from the Palette onto the design workspace: tMySqlConnection, tWaitForSqlData, tMysqlInput,
    tLogRow.

  • Connect the tMysqlConnection component to the
    tWaitforSqlData using an OnSubjobOK link, available on the right-click
    menu.

  • Then connect the tWaitForSqlData component to
    the subjob using an Iterate link as no actual
    data is transferred in this part. Indeed, simply a loop is implemented by the
    tWaitForSqlData until the condition is
    met.

  • On the subjob to be executed if the condition is met, a tMysqlInput is connected to the standard console component,
    tLogRow. As the connection passes on data,
    use a Row main link.

  • Now, set the connection to the table to check at regular intervals. On the
    Basic Settings view of the tMySqlConnection
    Component tab, set the DB connection
    properties.

Use_Case_tWaitForSqldata2.png
  • Fill out the Host, Port, Database, Username, Password
    fields to open the connection to the Database table.

  • Select the relevant Encoding if
    needed.

  • Then select the tWaitForSqlData component,
    and on the Basic Setting view of the Component tab, set its properties.

  • In the Wait at each iteration field, set the
    time in seconds you want to wait before the next iteration starts.

Use_Case_tWaitForSqldata3.png
  • In the Max iterations field, fill out the
    number of iterations max you want to have before the whole Job is forced to
    end.

  • The tWaitForSqlData component requires a
    connection to be open in order to loop on the defined number of iteration.
    Select the relevant connection (if several) in the Component List combo box.

  • In the Table to scan field, type in the name
    of the table in the DB to scan.In this example:
    test_datatypes.

  • In the Trigger action when rowcount is and
    Value fields, select the condition to be
    met, for the subjob to be triggered. In this use case, the number of rows in the
    scanned table should be greater or equal to 1.

  • In the Then field, select the action to be
    carried out when the condition is met before the number of iteration defined is
    reached. In this use case, as soon as the condition is met, the loop should be
    ended.

  • Then set the subjob to be executed when the condition set is met. In this use
    case, the subjob simply selects the data from the scanned table and displays it
    on the console.

  • Select the tMySqlInput component, and on the
    Basic Setting view of the Component tab, set the connection to the
    table.

Use_Case_tWaitForSqldata4.png
  • If the connection is set in the Repository, select the relevant entry on the
    list. Or alternatively, select the Use an existing
    connection
    check box and select the relevant connection component
    on the list.

  • In this use case, the schema corresponding to the table structure is stored in
    the Repository.

  • Fill out the Table Name field with the table
    the data is extracted from, Test_datatypes.

  • Then in the Query field, type in the Select
    statement to extract the content from the table.

  • No particular setting is required in the tLogRow component for this use case.

Then before executing the Job, make sure the table to scan
(test_datatypes) is empty, in order for the condition (greater
or equal to 1) to be met. Then execute the Job by pressing the F6 key on your keyboard. Before the end of the iterating loop, feed the
test_datatypes table with one or more rows in order to meet the condition.

Use_Case_tWaitForSqldata6.png

The Job ends when this table insert is detected during the loop, and the table content
is thus displayed on the console.

Use_Case_tWaitForSqldata5.png


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