Example: Suspended ResultSets

import java.sql.*;
import javax.sql.*;
import java.util.*;
import javax.transaction.*;
import javax.transaction.xa.*;
import com.ibm.db2.jdbc.app.*;

public class JTATxEffect {

    public static void main(java.lang.String[] args) {
        JTATxEffect test = new JTATxEffect();

        test.setup();
        test.run();
    }


    /**
     * Handle the previous cleanup run so that this test can recommence.
     */
    public void setup() {

        Connection c = null;
        Statement s = null;
        try {
            Class.forName("com.ibm.db2.jdbc.app.DB2Driver");
            c = DriverManager.getConnection("jdbc:db2:*local");
            s = c.createStatement();

            try {
                s.executeUpdate("DROP TABLE CUJOSQL.JTATABLE");
            } catch (SQLException e) {
                // Ignore... does not exist
            }

            s.executeUpdate("CREATE TABLE CUJOSQL.JTATABLE (COL1 CHAR (50))");
            s.executeUpdate("INSERT INTO CUJOSQL.JTATABLE VALUES('Fun with JTA')");
            s.executeUpdate("INSERT INTO CUJOSQL.JTATABLE VALUES('JTA is fun.)");

            s.close();
        } finally {
            if (c != null) {
                c.close();
            }
        }
    }


    /** 
     * This test uses JTA support to handle transactions.
     */
    public void run() {
        Connection c = null;

        try {
            Context ctx = new InitialContext();

            // Assume the data source is backed by a UDBXADataSource.
            UDBXADataSource ds = (UDBXADataSource) ctx.lookup("XADataSource");

            // From the DataSource, obtain an XAConnection object that
            // contains an XAResource and a Connection object.
            XAConnection  xaConn = ds.getXAConnection();
            XAResource    xaRes  = xaConn.getXAResource();
            Connection    c      = xaConn.getConnection();

            // For XA transactions, a transaction identifier is required.
            // An implementation of the XID interface is not included with
            // the JDBC driver. See Transactions with JTA
            // for a description of this interface to build a 
            // class for it.
            Xid xid = new XidImpl();

            // The connection from the XAResource can be used as any other 
            // JDBC connection.
            Statement stmt = c.createStatement();

            // The XA resource must be notified before starting any
            // transactional work.
            xaRes.start(xid, XAResource.TMNOFLAGS);

            // Create a ResultSet during JDBC processing and fetch a row.
            ResultSet rs = stmt.executeUpdate("SELECT * FROM CUJOSQL.JTATABLE");
            rs.next();

            // The end method is called with the suspend option. The 
            // ResultSets associated with the current transaction are 'on hold'.  
            // They are neither gone nor accessible in this state.
            xaRes.end(xid, XAResource.TMSUSPEND);

            
            // In the meantime, other work can be done outside the transaction.
            // The ResultSets under the transaction can be closed if the 
            // Statement object used to create them is reused.
            ResultSet nonXARS = stmt.executeQuery("SELECT * FROM CUJOSQL.JTATABLE");
            while (nonXARS.next()) {
                // Process here...
            }


            // Attempt to go back to the suspended transaction. The suspended
            // transaction's ResultSet has disappeared because the statement
            // has been processed again.
            xaRes.start(newXid, XAResource.TMRESUME);
            try {
                rs.next();
            } catch (SQLException ex) {
                System.out.println("This exception is expected. " +
                                   "The ResultSet closed due to another process.");
            }


            // When the transaction had completed, end it
            // and commit any work under it.
            xaRes.end(xid, XAResource.TMNOFLAGS);
            int rc = xaRes.prepare(xid);
            xaRes.commit(xid, false);


        } catch (Exception e) {
            System.out.println("Something has gone wrong.");
            e.printStackTrace();
        } finally {
            try {
                if (c != null)
                    c.close();
            } catch (SQLException e) {
                System.out.println("Note:  Cleaup exception.");
                e.printStackTrace();
            }
        }
    }
}