The aim of this book is to provide you, the Talend developer, with a set of common (and sometimes not so common) tasks and examples that, we hope, will help you in:
Developing Talend jobs more rapidly
Solving Talend issues more quickly
Gaining a wider knowledge of the Talend product
Gaining a better understanding of the capabilities of Talend
This cookbook is primarily intended as a reference guide, however, the chapters have been organized in such a way that it can also be used as a means of rapidly developing your Talend skills by working through the exercises in sequence from front to back.
For the more experienced developers, some of the recipes in this book may seem very simple, because they describe a feature of Talend that you may already know, but we are hoping that this isn't the case for everyone, and that there will be something in the book for developers of all levels of experience.
Many of the recipes in the book require you to complete sections of a partially built job, so it is assumed that in the real world you would be able to get to the starting point independently. Our thinking behind this is that we wanted to squeeze in as many recipes in the book as possible, so only the relevant steps that need to be performed and understood for a particular point to be made, are described in detail within each recipe.
Many any of the examples will write their output to the Talend log/console window when we could easily have written the data out to files or tables. However, the decision was made to provide an easy means (in most cases) of viewing the results of an exercise without having to leave the studio.
Before you begin the exercises in the book, it is worth becoming familiar with some of the key concepts and best practices.
Keep code changes small and test often
By keeping each change small, it is much easier to find where and what has caused problems during compilation and execution.
Chapter 10, Debugging, Logging, and Testing, is dedicated to debugging and logging; however, observing the preceding method will save time having to perform debugging steps that can sometimes take a long time.
Document your code
Talend sub-jobs have the ability to add titles, and every component in Talend has the option to add documentation for the component. Where you use Java, you should use the Java comment structures to document the code. Remember to use all these methods as you go along to ensure that your code is well documented.
Contexts and globalMap
globalMap are global areas used to store data that can be used by all components within a Talend job.
context variables are predefined prior to job execution in a
context group, whereas
globalMap variables are created on the fly at any point within a job.
To pass information into a job from the command line and/or a parent job
To manage values of parameters between environments
To store values within a job or set of jobs
Chapter 6, Managing Context Variables, is dedicated to the use and management of context variables within Talend
Almost every component will write information to
globalMaponce it completes execution (for example
NB_LINEis the number of rows processed in a component).
Certain components, such as
tFileList,will store data in
globalMapvariables for use by downstream components.
Talend is a Java code generator, so having a little Java knowledge can help when using Talend. There are many Java tutorials for beginners online, and a little time spent learning the basics will help speed up your understanding of Talend.
Other background knowledge
As a data integrator, you will be expected to understand many technologies and how to interface with them, and this book assumes a basic knowledge of many of the most frequent data sources and targets.
Chapter 7, Working with Databases, relates to using Talend with databases. We have chosen to use MySQL, because it is quick to install, simple to use, and readily available. Basic knowledge of SQL and MySQL will therefore be required to perform the exercises in this chapter.
Other chapters will also assume knowledge of csv files, MS Excel, XML, and web services.
All templates, completed code, and data are in the
cookbook.zipinto a folder on your machine.
Copy the directory
cookbookDatato a directory on your machine (we recommend
Download and install the latest version of Talend Open Studio for enterprise service bus (ESB) from www.talend.com.
Right mouse click on the Job Designs folder in the Repository panel, and select the option Import Items.
This opens the import wizard. Click the Select archive file option, and then navigate to your unzipped cookbook directory and select the zip file named
Click on Finish to import all the Talend artifacts.
If you copied your data to
C:\cookbookData,then you can ignore the next steps, and you have completed the installation of the cookbook software.
Open the cookbook context, as shown in the following screenshot, and click Next at the first window.
Click Finish to complete the installation process.
Many of the exercises rely on the use of tHashInput and tHashOutput components. Talend 5.2.3 does not automatically enable these components for use in jobs. To enable these components perform the instructions in the following section:
On the main menu bar navigate to File | Edit Project properties to open the properties dialogue.
Select Designer then Palette Settings.
Click on the Technical folder and then click on the button shown in the following screenshot to add this folder to the Show panel.
Click on OK to exit the project settings.