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Remoting JDO objects using RMI

Gopalan Suresh Raj

Note
To work with any of these samples, you will need the following:
.........................................JDK 1.2 or higher (I use JDK 1.3.1)
.........................................PE:JTM - The Productivity Environment for JavaTM (from HYWY Software Corporation)

 

Note: This article assumes that the reader has already created simple bank project using PE:J and JDO.

The Transfer Money Object Interaction Diagram is as shown below:

The Transfer Money logic is as follows:

  1. The IIOP Client (IIOPClient.java) obtains a reference to the TellerRemote (TellerRemote.java) remote object from Teller Server (TellerServer.java).

  2. The IIOP Client (IIOPClient.java) invokes the transferMoney() method of the TellerRemote (TellerRemote.java) object.

  3. The TellerRemote (TellerRemote.java) invokes the TransferMoney() method on the JDO Client (Teller.java).

  4. The JDO Client (Teller.java) obtains a configured PersistenceManagerFactory from the JDOAdapter.

  5. The JDO Client (Teller.java)  uses the configured PMF to get a PersistenceManager.

  6. The JDO Client (Teller.java)  uses the Persistence Manager to obtain a Transaction object.

  7. The JDO Client (Teller.java) begins a new Transaction using the Transaction object.

  8. The JDO Client (Teller.java) invokes the credit method on the Checking object.

  9. The JDO Client (Teller.java) then invokes the debit method on the Savings object.

  10. The JDO Client (Teller.java) then commits the transaction by invoking the method in the Transaction object.

  11. The JDO Client (Teller.java) then closes the Persistence Manager.

  12. The JDO Client (Teller.java) then closes the JDOAdapter.

 

 

com/hywy/samples/remote/TellerRemoteImpl.java
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/**
  * The following example illustrates an RMI-IIOP Server
  *
  * author: Gopalan Suresh Raj
  * Copyright (c), 2002. All Rights Reserved.
  * URL: http://gsraj.tripod.com/
  * email: gopalan@gmx.net
  */

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// To Compile
// cd C:\run\projects\bank\enhanced
// C:\java\jdk1.3\bin\rmic -classpath . -iiop -idl com.hywy.samples.remote.TellerRemoteImpl
// copy C:\run\projects\bank\enhanced\com\hywy\samples\remote\_TellerRemote_Stub.class C:\run\projects\bank\enhanced\com\hywy\samples\remote\client\
// copy C:\run\projects\bank\enhanced\com\hywy\samples\remote\_TellerRemoteImpl_Tie.class C:\run\projects\bank\enhanced\com\hywy\samples\remote\client\
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package com.hywy.samples.remote;

import java.util.ArrayList;
import java.util.Iterator;
import java.rmi.RemoteException;

import javax.rmi.PortableRemoteObject;

import com.hywy.samples.bank.Teller;

/**
* This component looks up the price of a given Stock Symbol
*
* @author Gopalan Suresh Raj
*/

public class TellerRemoteImpl extends PortableRemoteObject
  implements TellerRemote {

  /** The Teller reference */
  private Teller teller_;

  /**
   * Public No argument constructor
   */

  public TellerRemoteImpl() throws RemoteException {
    // Invoke the superclass to export this object
    super();
    this.teller_ = new Teller();
  }

  /**
   * Create Checking or Savings Account
   */

  public void createAccount(String customerNames,
                            int startingBalance,
                            boolean isCheckingAccount) throws RemoteException {
    try {
      this.teller_.createAccount(customerNames, startingBalance, isCheckingAccount);
    }
    catch(Exception exception) {
      throw new RemoteException(exception.toString());
    }
  }

  /**
   * Delete and close the account
   */

  public void deleteAccount(long accountNumber) throws RemoteException {
    try {
      this.teller_.deleteAccount(accountNumber);
    }
    catch(Exception exception) {
      throw new RemoteException(exception.toString());
    }
  }

  /**
   * Transfer Money
   */

  public boolean transferMoney(long fromAccountNumber,
                               long toAccountNumber,
                               int amount) throws RemoteException {
    boolean result = false;
    try {
      result = this.teller_.transferMoney(fromAccountNumber, toAccountNumber, amount);
    }
    catch(Exception exception) {
      throw new RemoteException(exception.toString());
    }
    return result;
  }

  /**
   * List out all Checking accounts found
   */

  public ArrayList listAllCheckingAccounts() throws RemoteException {
    String THIS = "listAllCheckingAccounts() - ";
    ArrayList list = null;
    Iterator iterator = null;
    try {
      list = this.teller_.listAllCheckingAccounts();
    }
    catch(Exception exception) {
      throw new RemoteException(exception.toString());
    }
    if(list != null) {
      iterator = list.iterator();
      while(iterator.hasNext()) {
        System.out.println(THIS+iterator.next().toString());
      }
    }
    return list;
  }

  /**
   * List out all Savings accounts found
   */

  public ArrayList listAllSavingsAccounts() throws RemoteException {
    String THIS = "listAllSavingsAccounts() - ";
    ArrayList list = null;
    Iterator iterator = null;
    try {
      list = this.teller_.listAllSavingsAccounts();
    }
    catch(Exception exception) {
      throw new RemoteException(exception.toString());
    }
    if(list != null) {
      iterator = list.iterator();
      while(iterator.hasNext()) {
        System.out.println(THIS+iterator.next().toString());
      }
    }
    return list;
  }

}

 

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About the Author...
Gopalan Suresh Raj is a Software Architect, Developer and an active Author. He has co-authored a number of books including "Professional JMS", "Enterprise Java Computing-Applications and Architecture" and "The Awesome Power of JavaBeans". His expertise spans enterprise component architectures and distributed object computing. Visit him at his Web Cornucopia site (http://gsraj.tripod.com/) or mail him at gopalan@gmx.net.

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This page has been visited times since February 26,2002.

Last Updated : Feb 26, 2002

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