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Pentaho Documentation

Embed Pentaho Data Integration

You can build and run PDI transformations and jobs in other Java applications. Examples of these types of PDI transformations and jobs are available in the kettle-sdk-embedding-samples directory of the accompany project within the sample code package. This sample project has a set of dependencies you should consider before using these example transformations and jobs.

Get Started with Embedding PDI

Consider the following dependencies while embedding PDI:

  • Complete Set of Dependent PDI Files
  • Default OSGi Features for PDI
  • Kettle (Non-OSGi) Plugins

Complete Set of Dependent PDI Files

The following PDI directories contain a complete set of all .jar files needed:

  • pentaho/design-tools/data-integration/lib
  • pentaho/design-tools/data-integration/libswt/<os>
  • pentaho/design-tools/data-integration/classes

These dependencies must be included in your class path. You can copy the directories into your project’s directory structure or specify the path directly to your PDI installation, as shown in the following example code:

java -classpath "lib/*;libswt/linux/*;classes/*" MyApp.java
java -classpath "$PDI_DI_DIR/lib/*;$PDI_DI_DIR/libswt/linux/*; $PDI_DI_DIR/classes/*" MyApp.java

OSGi Features for PDI

To use the OSGi features of PDI, make the pentaho/design-tools/data-integration/system directory available to your application. This directory is required for proper Karaf initialization. You can use either of following methods to specify this directory:

  • Copy the pentaho/design-tools/data-integration/system directory into the <working directory>/systems directory of your application.
  • Set the pentaho.user.dir system property to point to the PDI pentaho/design-tools/data-integration directory, either through the following command line option (-Dpentaho.user.dir=<pdi install>/data-integration) or directly in your code (System.setProperty( "pentaho.user.dir", new File("<pdi install>/data-integration") ); for example).

To enable non-default OSGi features of PDI, add the appropriate feature (.jar or .kar) to the pentaho/design-tools/data-integration/system/karaf/deploy directory. You do not need to restart your application for the enabled feature to take effect.

Kettle (Non-OSGi) Plugins

Make the kettle plugins (non-OSGi) available to your application. With a standard install, the kettle engine looks for plugins in either <working directory>plugins or <user.home>/.kettle/plugins. You can use either of following methods to make the default kettle plugins available:

  • Copy the pentaho/design-tools/data-integration/plugins directory into the <working directory>/plugins directory of your application.
  • Set the KETTLE_PLUGIN_BASE_FOLDERS system property to point to the PDI pentaho/design-tools/data-integration directory, either through the following command line option (-DKETTLE_PLUGIN_BASE_FOLDERS=<pdi install>/data-integration) or directly in your code (System.setProperty( "KETTLE_PLUGIN_BASE_FOLDERS", new File("<pdi install>/data-integration") ); for example).

Once the plugin location(s) are properly configured, you can add custom plugins to your specific locations. You can also add custom plugins in other locations as long as they are registered with the appropriate implementation of PluginTypeInterface prior to initializing the kettle environment, as shown in the following code example:

StepPluginType.getInstance().getPluginFolders().add( new PluginFolder( "<path to the plugin folder>" , false, true ) );

Sample Class Scenarios

For each of the following embedding scenarios, a sample class can be executed as a stand-alone Java application:

  • Run Transformations
  • Run Jobs
  • Dynamically Build Transformations 
  • Dynamically Build Jobs 

Each sample has an associated unit test. To run an individual sample, execute the following command:

mvn test -Dtest=<sample unit test class>

The following sections describe how to use these samples as templates for embedding PDI in your applications.

Run Transformations

The org.pentaho.di.sdk.samples.embedding.RunningTransformations class is an example of how to run a PDI transformation from Java code in a stand-alone application. This class sets parameters and executes the sample transformations in pentaho/design-tools/data-integration/etl directory. You can run a transform from its .ktr file using runTransformationFromFileSystem() or from a PDI repository using runTransfomrationFromRepository().

Consider the following general steps while trying to run an embedded transformation:

  1. Initialize the Kettle Environment
    Always make the first call to KettleEnvironment.init() whenever you are working with the PDI APIs.
  2. Prepare the Transformation
    The definition of a PDI transformation is represented by a TransMeta object. You can load this object from a .ktr file, a PDI repository, or generate it dynamically. To query the declared parameters of the transformation definition use listParameters(). To query the assigned values, use setParameterValue().
  3. Execute the Transformation
    An executable Trans object is derived from the TransMeta object that is passed to the constructor. The Trans object starts, then executes asynchronously. To ensure that all steps of the Trans object have completed, call waitUntilFinished().
  4. Evaluate the Outcome
    After the Trans object completes, you can access the result using getResult(). The Result object can be queried for success by evaluating getNrErrors(). This method returns zero (0) on success and a non-zero value when there are errors. To get more information, retrieve the transformation log lines.
  5. Shutdown Listeners
    When the transformations have completed, call KettleEnvironment.shutdown() to ensure the proper shutdown of all kettle listeners.

Run Jobs

The org.pentaho.di.sdk.samples.embedding.RunningJobs class is an example of how to run a PDI job from Java code in a stand-alone application. This class sets parameters and executes the job in etl/parametrized_job.kjb. You can run the job from the .kjb file using runJobFromFileSystem() or from a repository using runJobFromRepository().

Consider the following general steps while trying to run an embedded job:

  1. Initialize the Kettle Environment
    Always make the first call to KettleEnvironment.init() whenever you are working with the PDI APIs.
  2. Prepare the Job
    The definition of a PDI job is represented by a JobMeta object. You can load this object from a .ktb file, a PDI repository, or generate it dynamically. To query the declared parameters of the job definition use listParameters(). To set the assigned values use setParameterValue().
  3. Execute the Job
    An executable Job object is derived from the JobMeta object that is passed to the constructor. The Job object starts, then executes in a separate thread. To wait for the job to complete, call waitUntilFinished().
  4. Evaluate the Outcome
    After the Job completes, you can access the result using getResult(). The Result object can be queried for success using getResult(). This method returns true on success and false on failure. To get more information, retrieve the job log lines.
  5. Shutdown Listeners
    When the transformations have completed, call KettleEnvironment.shutdown() to ensure the proper shutdown of all kettle listeners.

Dynamically Build Transformations

The org.pentaho.di.sdk.samples.embedding.GeneratingTransformations class is an example of a dynamic transformation. This class generates a transformation definition and saves it to a .ktr file.

Consider the following general steps while trying to dynamically build a transformation:

  1. Initialize the Kettle Environment
    Always make the first call to KettleEnvironment.init() whenever you are working with the PDI APIs.
  2. Create and Configure a Transformation Definition Object
    A transformation definition is represented by a TransMeta object. Create this object using the default constructor. The transformation definition includes the name, the declared parameters, and the required database connections.
  3. Populate the TransMeta Object with Transformation Steps
    The data flow of a transformation is defined by steps that are connected by hops. Perform the following tasks to populate the object with a transformation step:

    1. Create the step by instantiating its class directly and configure it by using its get and set methods. Transformation steps reside in sub-packages of org.pentaho.di.trans.steps. For example, to use the Get File Names step , create an instance of org.pentaho.di.trans.steps.getfilenames.GetFileNamesMeta and use its get and set methods to configure it.
    2. Obtain the step ID string. Each PDI step has an ID that can be retrieved from the PDI plugin registry. A simple way to retrieve the step ID is to call PluginRegistry.getInstance().getPluginId(StepPluginType.class, theStepMetaObject)
    3. Create an instance of org.pentaho.di.trans.step.StepMeta by passing the step ID string, the name, and the configured step object to the constructor. An instance of StepMeta encapsulates the step properties, as well as controls the placement of the step on the PDI client (Spoon) canvas and connections to hops.
    4. Once the StepMeta object has been created, call setDrawn(true) and setLocation(x,y) to make sure the step appears correctly on the PDI client canvas.
    5. Add the step to the transformation, by calling addStep() on the transformation definition object.
  4. Connect the Hops
    Once steps have been added to the transformation definition, they need to be connected by hops. To create a hop, create an instance of org.pentaho.di.trans.TransHopMeta, passing in the From and To steps as arguments to the constructor. Add the hop to the transformation definition by calling addTransHop().

After all steps have been added and connected by hops, the transformation definition object can be serialized to a .ktr file by calling getXML() and opening it in the PDI client for inspection. The sample class org.pentaho.di.sdk.samples.embedding.GeneratingTransformations generates the following example transformation:
buildtransformationdynamically.png

Dynamically Build Jobs

The org.pentaho.di.sdk.samples.embedding.GeneratingJobs class is an example of a dynamic job. This class generates a job definition and saves it to a .kjb file.

Consider the following general steps while trying to dynamically build a job:

  1. Initialize the Kettle Environment
    Always make the first call to KettleEnvironment.init() whenever you are working with the PDI APIs.
  2. Create and Configure a Job Definition Object
    A job definition is represented by a JobMeta object. Create this object using the default constructor. The job definition includes the name, the declared parameters, and the required database connections.
  3. Populate the JobMeta Object with Job Entries
    The control flow of a job is defined by job entries that are connected by hops. Perform the following tasks to populate the object with a job entry:
    1. Create the entry by instantiating its class directly and configure it by using its get and set methods. Job entries reside in sub-packages of org.pentaho.di.job.entries. For example, use the File Exists job entry, create an instance of org.pentaho.di.job.entries.fileexists.JobEntryFileExists, and use setFilename() to configure it. The Start entry is implemented by org.pentaho.di.job.entries.special.JobEntrySpecial.
    2. Create an instance of org.pentaho.di.job.entry.JobEntryCopy by passing the entry created in the previous step to the constructor. An instance of JobEntryCopy encapsulates the properties of an entry, as well as controls the placement of the entry on the PDI client canvas and connections to hops.
    3. Once created, call setDrawn(true) and setLocation(x,y) to make sure the entry appears correctly on the PDI client canvas.
    4. Add the entry to the job by calling addJobEntry() on the job definition object. It is possible to place the same entry in several places on the canvas by creating multiple instances of JobEntryCopy and passing in the same entry instance. 
  4. Connect the Hops
    Once entries have been added to the job definition, they need to be connected by hops. To create a hop, create an instance of org.pentaho.di.job.JobHopMeta, by passing in the From and To entries as arguments to the constructor. Configure the hop consistently. Configure it as a green or red hop by calling setConditional() and setEvaluation(true/false). If it is an unconditional hop, call setUnconditional(). Add the hop to the job definition by calling addJobHop().

After all entries have been added and connected by hops, the job definition object can be serialized to a .kjb file by calling getXML(), and opened in the PDI client for inspection. The sample class org.pentaho.di.sdk.samples.embedding.GeneratingJobs generates the following example job:
buildjobdynamically.png

Obtain Logging Information

When you need more information about how transformations and jobs execute, you can view PDI log lines and text.

PDI collects log lines in a central place. The org.pentaho.di.core.logging.KettleLogStore class manages all log lines and provides methods for retrieving the log text for specific entities. To retrieve log text or log lines, supply the log channel ID generated by PDI during runtime. You can obtain the log channel id by calling getLogChannelId(), which is part of LoggingObjectInterface. Jobs, transformations, job entries, and transformation steps all implement this interface. 

For example, assuming the job variable is an instance of a running or completed job, the following code shows how you retrieve the job's log lines:

LoggingBuffer appender = KettleLogStore.getAppender();
String logText = appender.getBuffer(job.getLogChannelId(), false).toString();

The main methods in the sample classes org.pentaho.di.sdk.samples.embedding.RunningJobs and org.pentaho.di.sdk.samples.embedding.RunningTransformations retrieve log information from the executed transformation or job in this manner.

Expose a Transformation or Job as a Web Service

You can run a PDI transformation or job as part of a web-service by developing one of the following implementations:

  • Write a servlet that maps incoming parameters for a transformation step or job entry and executes them as part of the request cycle.
  • Use the Carte server or the Pentaho Server directly by building a transformation that writes its output to the HTTP response of the Carte server. Then, specify the Pass Output to Servlet option in the Text Output, XML Output, JSON Output, or scripting steps to write output to the HTTP response. For an example, run the pentaho/design-tools/data-integration/samples/transformations/Servlet Data Example.ktr sample transformation on Carte.

Use Non-Native Plugins

To use non-native plugins with an embedded Pentaho Server, you must configure the server to find where the plugins reside. How you configure the server depends on whether your plugin is a directory with associated files or a single JAR file.

If your plugins are directories with associated files, register the directories by setting the KETTLE_PLUGIN_BASE_FOLDERS system property just before the call to KettleEnvironment.init(), as shown in the following example for the “plugins” and “plugins2” plugins:

System.setProperty("KETTLE_PLUGIN_BASE_FOLDERS", "C:\\pentaho\\data-integration\\plugins,c:\\plugins2");
KettleEnvironment.init();

If your plugin is a single JAR file, annotate the classes for the plugin and include them in the class path, then set the KETTLE_PLUGIN_CLASSES system property to register the fully-qualified class names just before the call to KettleEnvironment.init(), as shown in the following example for a “jsonoutput” plugin:

System.setProperty("KETTLE_PLUGIN_CLASSES","org.pentaho.di.trans.steps.jsonoutput.JsonOutputMeta");
KettleEnvironment.init();

Refer to the Extend Pentaho Data Integration article for more information on creating plugins.

If you have custom custom transformation steps or job entries, you must use one of the above two methods to configure the locations where the embedded server will search for your custom transformation steps or custom job entries.