JDBCCallableStatementReaderPattern
This pattern is used to implement the business logic of processing data from a Java™ Database Connectivity (JDBC) connection using a stored procedure. The administrative tasks of opening and closing the connection are done by the batch framework.
Supporting classes
- JDBCCallableStatementReader
This class is referenced when the usage pattern of your 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.
- 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) | Enables Cursor Holdability for this BDS Reader | Applicable | Applicable |
debug | true or false. The default value is false. | Enables detailed tracing on this batch data stream. | Applicable | Applicable |
EnablePerformanceMeasurement | true or false. The default value is false. | Calculates the total time spent in the batch data streams and the processRecord method, if you are using the GenericXDBatchStep. | Applicable | Applicable |
EnableDetailedPerformanceMeasurement | true or false. The default value 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>