Example: Developing your own DataStoreHelper class

 

Apply the WebSphere extension, GenericDataStoreHelper class, to create your own data store helper for data sources that WebSphere Application Server does not support. With this helper class, your JDBC configuration can use database-specific functions during transactions.

This code example subclasses the GenericDataStoreHelper class to extend the capabilities of a JDBC driver in a user-defined data source configuration. (This type of data source is based on a user-defined JDBC provider.)

 package com.ibm.websphere.examples.adapter;
 import java.sql.SQLException; import javax.resource.ResourceException;
 import com.ibm.websphere.appprofile.accessintent.AccessIntent; import com.ibm.websphere.ce.cm.*; import com.ibm.websphere.rsadapter.WSInteractionSpec;

/**
* Example DataStoreHelper class, demonstrating how to create a user-defined DataStoreHelper.
* Implementation for each method is provided only as an example.  More detail would likely be
* required for any custom DataStoreHelper created for use by a real application.
*/ public class ExampleDataStoreHelper extends com.ibm.websphere.rsadapter.GenericDataStoreHelper
{
    static final long serialVersionUID = 8788931090149908285L;


    public ExampleDataStoreHelper(java.util.Properties props)
    {
        super(props);

        // Update the DataStoreHelperMetaData values for this helper.
        getMetaData().setGetTypeMapSupport(false);

        // Update the exception mappings for this helper.
        java.util.Map xMap = new java.util.HashMap();

        // Add an Error Code mapping to StaleConnectionException.
        xMap.put(new Integer(2310),  StaleConnectionException.class);
        // Add an Error Code mapping to DuplicateKeyException.
        xMap.put(new Integer(1062),  DuplicateKeyException.class);
        // Add a SQL State mapping to the user-defined ColumnNotFoundException
        xMap.put("S0022",            ColumnNotFoundException.class);
        // Undo an inherited StaleConnection SQL State mapping.
        xMap.put("S1000",            Void.class);

        setUserDefinedMap(xMap);

        // If you are extending a helper class, it is
        // normally not necessary to issue 'getMetaData().setHelperType(...)'
        // because your custom helper will inherit the helper type from its
        //   parent class.
                          

         }

    public void doStatementCleanup(java.sql.PreparedStatement stmt) throws SQLException
    {
        // Clean up the statement so it may be cached and reused.

        stmt.setCursorName("");
        stmt.setEscapeProcessing(true);
        stmt.setFetchDirection(java.sql.ResultSet.FETCH_FORWARD);
        stmt.setMaxFieldSize(0);
        stmt.setMaxRows(0);
        stmt.setQueryTimeout(0);
    }


    public int getIsolationLevel(AccessIntent intent) throws ResourceException
    {
        // Determine an isolation level based on the AccessIntent.

        if (intent == null) return java.sql.Connection.TRANSACTION_SERIALIZABLE;

        return intent.getConcurrencyControl() == AccessIntent.CONCURRENCY_CONTROL_OPTIMISTIC ?
               java.sql.Connection.TRANSACTION_READ_COMMITTED :
               java.sql.Connection.TRANSACTION_REPEATABLE_READ;
    }
        public int getLockType(AccessIntent intent) {
           if ( intent.getConcurrencyControl() == AccessIntent.CONCURRENCY_CONTROL_PESSIMISTIC) {
              if ( intent.getAccessType() == AccessIntent.ACCESS_TYPE_READ ) {
                  return WSInteractionSpec.LOCKTYPE_SELECT;
              }
              else {
                  return WSInteractionSpec.LOCKTYPE_SELECT_FOR_UPDATE;
               }
           }
           return WSInteractionSpec.LOCKTYPE_SELECT;
        }


    public int getResultSetConcurrency(AccessIntent intent) throws ResourceException
    {
        // Determine a ResultSet concurrency based on the AccessIntent.

        return intent == null || intent.getAccessType() == AccessIntent.ACCESS_TYPE_READ ?
               java.sql.ResultSet.CONCUR_READ_ONLY :
               java.sql.ResultSet.CONCUR_UPDATABLE;
    }


    public int getResultSetType(AccessIntent intent) throws ResourceException
    {
        // Determine a ResultSet type based on the AccessIntent.

        if (intent == null) return java.sql.ResultSet.TYPE_SCROLL_INSENSITIVE;

        return intent.getCollectionAccess() == AccessIntent.COLLECTION_ACCESS_SERIAL ?
               java.sql.ResultSet.TYPE_FORWARD_ONLY :
               java.sql.ResultSet.TYPE_SCROLL_SENSITIVE;
    }
}

 

ColumnNotFoundException

package com.ibm.websphere.examples.adapter;
 import java.sql.SQLException; import com.ibm.websphere.ce.cm.PortableSQLException;

/**
* Example PortableSQLException subclass, which demonstrates how to create a user-defined
* exception for exception mapping.
*/ public class ColumnNotFoundException extends PortableSQLException
{
    public ColumnNotFoundException(SQLException sqlX)
    {
        super(sqlX);
    }
}

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Related concepts

Resource adapters

 

Reference topic