PureQueryReaderPattern

Use this pattern is used to read data from a database using IBM Optim™ pureQuery Runtime. The batch data stream (BDS) framework completes the administrative tasks of opening and closing connections.

Supporting classes

The PureQueryReader class implements the basic operations of opening and closing database connections and obtaining the IBM Optim pureQuery Runtime data.

Required properties

The following properties are required for the pattern.

Property name	Value
PATTERN_IMPL_CLASS	Class implementing PureQueryReaderPattern interface
PQ_DATA_BEAN_INTERFACE	PureQuery data bean interface
ds_jndi_name	JNDI name of the data source to access the database

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
DB_SCHEMA	null	Database schema name
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

The PureQueryReaderPattern Interface definition shows the methods that we must implement to support the PureQueryReaderPattern interface.

public interface PureQueryReaderPattern
{

	/**
	 * This method is called by the batch container during step setup. The properties passed
	 * in are the ones that we provide in the xJCL BDS level properties.
	 * @param properties 	 */
    public  void initialize(Properties properties);

    /**
     * Invoked by the container during each iteration of the batch loop. This code obtains
     * the next record using the given iterator object.
     * @param iterator
     * @return
     */
    public  Object fetchRecord(Iterator iterator);

    /**
     * Return the iterator based on the passed data object used to iterate 
     * over the records
     * @param data
     * @return
     */
    public  Iterator getInitialIterator(Data data);

    /**
     * Return the iterator based on the passed data object repositioned based on the restart
     * token of restartToken.
     * @param data
     * @param s
     * @return
     */
    public  Iterator getRestartIterator(Data data, String restartToken);

    /**
     * Invoked before a checkpoint is taken to save the restart token used in case 
     * of a restart
     * @return
     */
    public  String getRestartTokens();
}   

xJCL example

The example shows xJCL we can use to define a batch datastream which implements the PureQueryReaderPattern interface in the application.

<batch-data-streams> 
<bds>
 		<logical-name>outputStream</logical-name>
 		<props>
 			<prop name="IMPLCLASS" value="com.ibm.MyWriterPattern"/>
               <prop name="ds_jndi_name" value="jdbc/crreport"/>
               <prop name="debug" value="true"/>
               <prop name="DB_SCHEMA" value="PQDS"/>
               <prop name="PQ_DATA_BEAN_INTERFACE" value="com.ibm.MyEmployeeData"/>
 			</props>
 			<impl-class>com.ibm.websphere.batch.devframework.datastreams.patterns.PureQueryReader</impl-class>
  </bds></batch-data-streams> 

Related:

Batch data stream framework and patterns

Use the batch data stream framework

Task overview: IBM Optim pureQuery Runtime

JDBCReaderPattern

JPAReaderPattern

JPAWriterPattern

ByteReaderPattern

ByteWriterPattern

FileReaderPattern

FileWriterPattern

PureQueryWriterPattern

(ZOS) RecordOrientedDatasetReaderPattern

(ZOS) RecordOrientedDataSetWriterPattern