How to handle Connection in a SLSB

Question

I am reading EJB in j2ee tutorial 1.4 and in the Bank example I saw that for each private method, first a connection is obtained then work is completed and then the connection is closed.
    private void updateChecking(double amount) throws SQLException {
        makeConnection();
        releaseConnection();
    private void updateSaving(double amount) throws SQLException {
        makeConnection();
        releaseConnection();
    public void transferToSaving(double amount)
        throws InsufficientBalanceException {
        checkingBalance -= amount;
        savingBalance += amount;
        try {
            updateChecking(checkingBalance);
            if (checkingBalance < 0.00) {
                context.setRollbackOnly();
                throw new InsufficientBalanceException();
            updateSaving(savingBalance);
        } catch (SQLException ex) {
            throw new EJBException("Transaction failed due to SQLException: " +
                ex.getMessage());
    }Is this the recommended approach? I find it problemetic that one Logical Unit of Work "the transferToSaving() method" is opening and closing Connection twice.
I am thinking that a better approach would be to get Connection in transferToSaving() method then pass Connection as an argument to both updateChecking() and updateSaving() methods.
    private void updateChecking(Connection conn, double amount) throws SQLException {
    private void updateSaving(Connection conn, double amount) throws SQLException {
    public void transferToSaving(double amount)
        throws InsufficientBalanceException {
        checkingBalance -= amount;
        savingBalance += amount;
        try {
            makeConnection();
            updateChecking(checkingBalance);
            if (checkingBalance < 0.00) {
                context.setRollbackOnly();
                throw new InsufficientBalanceException();
            updateSaving(savingBalance);
        } catch (SQLException ex) {
            throw new EJBException("Transaction failed due to SQLException: " +
                ex.getMessage());
        } finally {
        releaseConnection();
    }Am i right? If yes then how come the guys at Sun are recommending a wrong approach?
Thanks

Answer 1

What is your question really about? You seem to be
going in circles.
Ok. Here is my question refined:
I am reading SLSB EJB in j2ee tutorial 1.4 and in the Bank example I saw that for each business private method, first a connection is obtained then work is completed and then the connection is closed. For example:
public class BankBean implements SessionBean, SessionSynchronization {
    private Connection con;
    public void transferToSaving(double amount) throws InsufficientBalanceException {
        checkingBalance -= amount;
        savingBalance += amount;
        try {
            updateChecking(checkingBalance);
            if (checkingBalance < 0.00) {
                context.setRollbackOnly();
                throw new InsufficientBalanceException();
            updateSaving(savingBalance);
        } catch (SQLException ex) {
            throw new EJBException("Transaction failed due to SQLException: " +
                ex.getMessage());
    private void updateChecking(double amount) throws SQLException {
        makeConnection();
        String updateStatement =
            "update checking set balance =  ? " + "where id = ?";
        PreparedStatement prepStmt = con.prepareStatement(updateStatement);
        prepStmt.setDouble(1, amount);
        prepStmt.setString(2, customerId);
        prepStmt.executeUpdate();
        prepStmt.close();
        releaseConnection();
    private void updateSaving(double amount) throws SQLException {
        makeConnection();
        String updateStatement =
            "update saving set balance =  ? " + "where id = ?";
        PreparedStatement prepStmt = con.prepareStatement(updateStatement);
        prepStmt.setDouble(1, amount);
        prepStmt.setString(2, customerId);
        prepStmt.executeUpdate();
        prepStmt.close();
        releaseConnection();
    private void makeConnection() {
        try {
            InitialContext ic = new InitialContext();
            DataSource ds = (DataSource) ic.lookup(dbName);
            con = ds.getConnection();
        } catch (Exception ex) {
            throw new EJBException("Unable to connect to database. " +
                ex.getMessage());
    private void releaseConnection() {
        try {
            con.close();
        } catch (SQLException ex) {
            throw new EJBException("releaseConnection: " + ex.getMessage());
}Is this the recommended approach? I find it problemetic that one Logical Unit of Work "the transferToSaving() method" is opening and closing Connection twice.
I am thinking that a better approach would be to first get Connection in transferToSaving() method then call both updateChecking() and updateSaving() methods and then close Connection in transferToSaving() method.
So I would make following changes in the above code:
public void transferToSaving(double amount) throws InsufficientBalanceException {
        checkingBalance -= amount;
        savingBalance += amount;
        try {
            makeConnection();
            updateChecking(checkingBalance);
            if (checkingBalance < 0.00) {
                context.setRollbackOnly();
                throw new InsufficientBalanceException();
            updateSaving(savingBalance);
        } catch (SQLException ex) {
            throw new EJBException("Transaction failed due to SQLException: " +
                ex.getMessage());
        } finally {
            releaseConnection();
    private void updateChecking(double amount) throws SQLException {
        String updateStatement =
            "update checking set balance =  ? " + "where id = ?";
        PreparedStatement prepStmt = con.prepareStatement(updateStatement);
        prepStmt.setDouble(1, amount);
        prepStmt.setString(2, customerId);
        prepStmt.executeUpdate();
        prepStmt.close();
    private void updateSaving(double amount) throws SQLException {
        String updateStatement =
            "update saving set balance =  ? " + "where id = ?";
        PreparedStatement prepStmt = con.prepareStatement(updateStatement);
        prepStmt.setDouble(1, amount);
        prepStmt.setString(2, customerId);
        prepStmt.executeUpdate();
        prepStmt.close();
    }Am i right? If yes then how come the guys at Sun are recommending a wrong approach?
Thanks