JDBCCallableStatementReaderPattern

This pattern is used to implement the business logic of processing data from a JDBC connection using a stored procedure. The administrative tasks of opening and closing the connection are done by the batch framework.

Supporting classes

1. JDBCCallableStatementReader

   This class is referenced when the usage pattern of our JDBC input stream retrieves a single result from a query. The query and results are discarded after every iteration of the step. This class differs from JDBCReader in that it uses a callable statement instead of a prepared statement.

2. LocalJDBCCallableStatementReader

   This class is referenced when data is read from a local database.

Required properties

The following properties are required for the pattern.

Property	Value	JDBCCallableStatementReader	LocalJDBCCallableStatementReader
PATTERN_IMPL_CLASS	The class implementing JDBCCallableStatementReaderPattern interface.	Applicable	Applicable
ds_jndi_name	The data source JNDI name.	Applicable	Applicable
jdbc_url	The JDBC URL. For example, jdbc:derby:C:\\mysample\\CREDITREPORT.	Not applicable	Applicable
jdbc_driver	The JDBC driver. For example, org.apache.derby.jdbc.EmbeddedDriver	Not applicable	Applicable
userid	The user ID for the database.	Not applicable	Applicable
pswd	The user password.	Not applicable	Applicable

Optional properties

The following properties are optional for the pattern.

Property name	Value	Description	JDBCCallableStatementReader	LocalJDBCCallableStatementReader
CursorHoldabilityEnabled	true or false (default is false)	Enable Cursor Holdability for this BDS Reader	Applicable	Applicable
debug	true or false. The default is false.	Enable detailed tracing on this batch data stream.	Applicable	Applicable
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.	Applicable	Applicable
EnableDetailedPerformanceMeasurement	true or false. The default is false.	Provides a more detailed breakdown of time spent in each method of the batch data streams.	Applicable	Applicable

Interface definition

public interface JDBCCallableStatementReaderPattern {

		 /**
		  * This method is invoked during the job setup phase. 
		  * 
		  * @param props properties provided in the xJCL 
		  */
		 
		 public void initialize(Properties props);
		 
		 /**
	 * This method should retrieve values for the various columns for the current row from
	 * the given resultset object. Typically this data would be used to populate an 	 * intermediate object which would be returned
	 * @param resultSet
	 * @return
	 */
		 public Object fetchRecord(ResultSet resultSet);
		 
		 /**
	 * This method should return a ResultSet used by the stream to retrieve all relevant
	 * data that would be processed part of the job steps.
	 */
	public ResultSet getResultSet(CallableStatement cstmt) throws SQLException ;

	/**
	 * This method should return a Callable statement that will be used during setup of the 	 * stream to retrieve all relevant data that would be processed as part of the job steps.
	 * @return object to be used during process step.
	 */
	public CallableStatement getInitialCallableStatement(Connection con);
	
	/**
	 * This method gets called during Job Restart. The restart token should be used to create
	 * a Callable Statement that will retrieve previously unprocessed records. 
	 * Typically the restart token would be the primary key in the table and the query would
	 * get all rows with primary key value > restarttoken
	 * @param restartToken
	 * @return The restart query
	 */
	public CallableStatement getRestartCallableStatement(Connection con,String restartToken);
	
	/**
	 * This method gets called just before a checkpoint is taken.
	 * @return The method should return a string value identifying the last record read by the stream.
	 */
	public String getRestartTokens();
		 		 
}

JDBCCallableStatementReader xJCL example

<batch-data-streams>
<bds>
<logical-name>inputStream</logical-name>
<props>
<prop name="IMPLCLASS" value="com.ibm.websphere.batch.samples.tests.bds.EchoReader"/>
<prop name="ds_jndi_name" value="jdbc/echojndi"/>
<prop name="debug" value="false"/>
<prop name="EnablePerformanceMeasurement" value="true"/> 
</props>
<impl-class>com.ibm.websphere.batch.devframework.datastreams.patterns.JDBCCallableStatementReader</impl-class>
</bds>
</batch-data-streams>

Related:

Batch data stream framework and patterns

Use the batch data stream framework

JDBCWriterPattern

ByteReaderPattern

ByteWriterPattern

FileReaderPattern

FileWriterPattern

(ZOS) RecordOrientedDatasetReaderPattern

(ZOS) RecordOrientedDataSetWriterPattern

JPAReaderPattern

JPAWriterPattern