JPAWriterPattern

The JPAWriterPattern pattern is used to write data to a database using a Java Persistence API (JPA) connection.

Supporting classes

The JPAWriter class implements the basic JPA operations of obtaining an EntityManager class and joining, beginning, and committing transactions. By default the JPAWriter joins an existing global transaction.

Package a persistence.xml file that sets the transaction-type attribute to JTA and declares a jta-data-source element. Optionally configure the JPAWriter class to begin and commit transactions in synchronization with the global transactions. These transactions are used with non-jta-data-source elements and connection URLs. In this case the persistence.xml file sets the transaction-type to RESOURCE_LOCAL and declare a non-jta-data-source element or connection URLs.

Required properties

The following properties are required for the pattern.

Property name	Value
PATTERN_IMPL_CLASS	Class implementing JPAWriterPattern interface
PERSISTENT_UNIT	The provider persistent unit name
JPA properties that we set on the EntityManager class	The value of these properties

Optional properties

The following properties are optional for the pattern.

Property name	Value	Description
debug	true or false (The default is false.)	Enable detailed tracing on this batch data stream.
use_JTA_transactions	true or false (The default is true.)	If we use the non-jta-data-source element or connection URLs, set the value to false.
EnablePerformanceMeasurement	true or false (The default is false.)	Calculates the total time spent in the batch data-streams and the processRecord method, if we are using the GenericXDBatchStep.

Interface definition

public interface JPAWriterPattern {

	/**
	 * This method is invoked during create job step to allow the JPAWriter stream to 	 * initialize. 
	 * @param props Properties passed via xJCL 
	 */
public void initialize(Properties props);
	
	/**
	 * This method is invoked to actually persist the passed object to the database
	 * using JPA EntityManager 
	 * @param manager
	 * @param record
	 */
	public void writeRecord(EntityManager manager, Object record);
}  

xJCL example

<batch-data-streams> 
<bds>  
<logical-name>outputStream</logical-name>  
<props>  
<prop name="PATTERN_IMPL_CLASS" value="com.ibm.websphere.batch.samples.tests.bds.EchoWriter"/>  
<prop name="PERSISTENT_UNIT" value="mypersistentU"/>  
<prop name="debug" value="true"/>  
</props>  
<impl-class>com.ibm.websphere.batch.devframework.datastreams.patterns.JPAWriter</impl-class>  
</bds>  
</batch-data-streams> 

Related:

Batch data stream framework and patterns

Use the batch data stream framework

JDBCReaderPattern

JPAReaderPattern

ByteReaderPattern

ByteWriterPattern

FileReaderPattern

FileWriterPattern

(ZOS) RecordOrientedDatasetReaderPattern

(ZOS) RecordOrientedDataSetWriterPattern