tDotNETRow - 6.2

Talend Open Studio for Big Data Components Reference Guide

EnrichVersion
6.2
EnrichProdName
Talend Open Studio for Big Data
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Function

tDotNETRow sends data to and from libraries and classes within .NET or other custom DLL files.

Purpose

tDotNETRow helps you facilitate data transform by utilizing custom or built-in .NET classes.

tDotNETRow properties

Component family

DotNET

 

 Basic settings

Schema and Edit schema

A schema is a row description, it defines the number of fields to be processed and passed on to the next component. The schema is either built-in or remotely stored in the Repository.

Since version 5.6, both the Built-In mode and the Repository mode are available in any of the Talend solutions.

 

 

Built-in: No property data stored centrally.

 

 

Repository: Select the Repository file where properties are stored. The following fields are pre-filled in using fetched data

  Use a static method

Select this check box to invoke a static method in .NET and this will disable Use an existing instance check box.

  Propagate a data to output

Select this check box to propagate a transformed data to output.

  Use an existing instance

Select this check box to reuse an existing instance of a .NET object from the Existing instance to use list.

Existing instance to use: Select an existing instance of .NET objects created by the other .NET components from the list.

Note

This check box will be disabled if you have selected Use a static method and selecting this check box will disable Dll to load, Fully qualified class name(i.e. ClassLibrary1.NameSpace2.Class1) and Value(s) to pass to the constructor.

 

Dll to load

Type in the path, or browse to the DLL library containing the class(es) of interest or enter the assembly's name to be used. For example, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 for an OleDb assembly.

 

 Fully qualified class name(i.e. ClassLibrary1.NameSpace2.Class1)

Enter a fully qualified name for the class of interest.

 

 Method name

Fill this field with the name of the method to be invoked in .NET.

  Value(s) to pass to the constructor

Click the plus button to add one or more lines for values to be passed to the constructor for the object. Or, leave this table empty to call a default constructor for the object.

The valid value(s) should be the parameters required by the class to be used.

  Method Parameters

Click the plus button to add one or more lines for parameters to be passed to the method.

  Output value target column

Select a column in the output row from the list to put value into it.

 Advanced settings Create a new instance at each row

Select this check box to create a new instance at each row that passes through the component.

  Method doesn't return a value

Select this check box to invoke a method without returning a value as a result of the processing.

  Returns an instance of a .NET Object

Select this check box to return an instance of a .NET object as a result of a invoked method.

  Store the returned value for later use

Select this check box to store the returned value of a method for later reuse in another tDotNETRow component.

 

tStatCatcher Statistics

Select this check box to collect log data at the component level.

Global Variables

NB_LINE: the number of rows processed. This is an After variable and it returns an integer.

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 utilized to integrate with .NET objects.

To use this component, you must first install the runtime DLLs, for example janet-win32.dll for Windows 32-bit version and janet-win64.dll for Windows 64-bit version, from the corresponding Microsoft Visual C++ Redistributable Package. This allows you to avoid errors like the UnsatisfiedLinkError on dependent DLL.

So ensure that the runtime and all of the other DLLs which the DLL to be called depends on are installed and their versions are consistent among one another.

Note

The required DLLs can be installed in the System32 folder or in the bin folder of the Java runtime to be used.

If you need to export a Job using this component to run it outside the Studio, you have to specify the runtime container of interest by setting the -Djava.library.path argument accordingly.

Scenario: Utilizing .NET in Talend

This scenario describes a three-component Job that uses a DLL library containing a class called Test1.Class1 Class and invokes a method on it that processes the value and output the result onto the console.

Prerequisites

Before replicating this scenario, you need first to build up your runtime environment.

  • Create the DLL to be loaded by tDotNETInstantiate

    This example class built into .NET reads as follows:

    using System;
    using System.Collections.Generic;
    using System.Text;
    
    
    namespace Test1
    {
        public class Class1
        {
            string s = null;
            public Class1(string s)
            {
                this.s = s;
            }
    
            public string getValue()
            {
                return "Return Value from Class1: " + s;
            }
    
        }
        }

    This class reads the input value and adds the text Return Value from Class1: in front of this value. It is compiled using the latest .NET.

  • Install the runtime DLL from the latest .NET. In this scenario, we use janet-win32.dll on Windows 32-bit version and place it in the System32 folder.

    Thus the runtime DLL is compatible with the DLL to be loaded.

Connecting components

  1. Drop the following components from the Palette to the design workspace: tDotNETInstantiate, tDotNETRow and tLogRow.

  2. Connect tDotNETInstantiate to tDotNETRow using a Trigger On Subjob OK connection.

  3. Connect tDotNETRow to tLogRow using a Row Main connection.

Configuring tDotNETInstantiate

  1. Double-click tDotNETInstantiate to display its Basic settings view and define the component properties.

  2. Click the three-dot button next to the Dll to load field and browse to the DLL file to be loaded. Alternatively, you can fill the field with an assembly. In this example, we use :

    "C:/Program Files/ClassLibrary1/bin/Debug/ClassLibrary1.dll""

  3. Fill the Fully qualified class name field with a valid class name to be used. In this example, we use:

    "Test1.Class1"

  4. Click the plus button beneath the Value(s) to pass to the constructor table to add a new line for the value to be passed to the constructor.

    In this example, we use:

    "Hello world"

Configuring tDotNETRow

  1. Double-click tDotNETRow to display its Basic settings view and define the component properties.

  2. Select Propagate data to output check box.

  3. Select Use an existing instance check box and select tDotNETInstantiate_1 from the Existing instance to use list on the right.

  4. Fill the Method Name field with a method name to be used. In this example, we use "getValue", a custom method.

  5. Click the three-dot button next to Edit schema to add one column to the schema.

    Click the plus button beneath the table to add a new column to the schema and click OK to save the setting.

  6. Select newColumn from the Output value target column list.

Configuring tLogRow

  1. Double-click tLogRow to display its Basic settings view and define the component properties.

  2. Click Sync columns button to retrieve the schema defined in the preceding component.

  3. Select Table in the Mode area.

Save your Job and press F6 to execute it.

From the result, you can read that the text Return Value from Class1 is added in front of the retrieved value Hello world.