Developing JBP applications with the IMS Java dependent region resource adapter

Code sample of JBP symbolic checkpoint and restart

The following symbolic checkpoint/restart sample JBP application demonstrates the use of the checkpoint and restart functionality support with the IMS Java dependent region resource adapter.

The two symbolic checkpoint methods checkpoint() andcheckpoint(SaveArea saveArea) require the application to be restarted (in the case of any abnormal end of the program) using the 4-character constant LAST.

package samples.dealership.chkp_xrst;

import java.sql.*;
import java.io.*;

import com.ibm.ims.dli.DLIException;
import com.ibm.ims.dli.tm.Application;
import com.ibm.ims.dli.tm.ApplicationFactory;
import com.ibm.ims.dli.tm.SaveArea;
import com.ibm.ims.dli.tm.Transaction;
import com.ibm.ims.jdbc.IMSDataSource;

public class CheckpointRestartAutoSample {

    private SaveArea saveAreaOut;
    private Connection connection;
    private Transaction transaction;

    // The entry point of the application
    public static void main(String[] args) throws Exception {
        CheckpointRestartAutoSample crSample 
          = new CheckpointRestartAutoSample();

        crSample.setup();

        crSample.runSample();

        crSample.closeDown();

    }

    // Set up for the application: 
    //  1. Enable trace
    //  2. Creates connection
    void setup() throws Exception {
        this.createConnection();
        Application app = ApplicationFactory.createApplication();
        this.transaction = app.getTransaction();
    }

    void closeDown() throws Exception {
        // close the connection
        connection.close();

        // Commit the IMS DB work
        this.transaction.commit();
    }

    // Creates a connection to the auto dealership database
    void createConnection() throws Exception {
        try {
            IMSDataSource ds = new IMSDataSource();
         ds.setDriverType(IMSDataSource.DRIVER_TYPE_2);
         ds.setMetadataURL("class://samples.dealership.AUTPSB11DatabaseView");

            connection = ds.getConnection();

        } catch (SQLException e) {
            String errorMessage 
               = new String("During connection creation: " 
                   + e.toString());
            throw new Exception(errorMessage);
        }
    }

    void runSample() throws Exception {
        // the restart call is always the first call in a  
        // checkpoint/restart application
        saveAreaOut = this.transaction.restart();

        // if the SaveArea object returned is null it  
        // is a normal program start, otherwise it is a restart 
        if (saveAreaOut != null) {
            // Check the SaveArea object to determine 
               // where to restart from
            if (saveAreaOut.isEmpty()) {
                sqlMethod(true);
            } else {
                String str = 
                   (String)saveAreaOut.getObject(1);
                System.out.println("Retrieved string = "+str);
            }
        } else {
            sqlMethod(false);
        }
    }

    void sqlMethod(boolean isRestart) 
       throws DLIException, SQLException {

        String sql 
          = new String("SELECT * FROM Dealer.DealerSegment");
        Statement statement = connection.createStatement();
        ResultSet results = statement.executeQuery(sql);

        // this part of the code will be executed only during a normal
        // program start
        if (!isRestart && results.next()) {
            System.out.println("At first GetSegment call to the DealerDB: ");
            System.out.println("Dealer Number = " 
               + results.getString("DealerNo"));
            System.out.println("Dealer Name   = " 
               + results.getString("DealerName"));
            System.out.println("DealerCity    = " 
               + results.getString("DealerCity"));
            System.out.println("DealerZip     = " 
               + results.getString("DealerZip"));
            System.out.println("DealerPhone   = " 
               + results.getString("DealerPhone"));
        }

        //String ckptid = null;
        for (int i=1; results.next(); i++) {
            System.out.println("GetSegment call to the DealerDB:");
            System.out.println("Dealer Number = " 
               + results.getString("DealerNo"));
            System.out.println("Dealer Name   = " 
               + results.getString("DealerName"));
            System.out.println("DealerCity    = " 
               + results.getString("DealerCity"));
            System.out.println("DealerZip     = " 
               + results.getString("DealerZip"));
            System.out.println("DealerPhone   = " 
               + results.getString("DealerPhone"));

       // The checkpoint call, apart from storing program information, 
       // causes the program to lose its position in the database
            this.transaction.checkpoint();
        }
    }

}