Middleware Programming - JMS

DDeevveellooppiinngg CChhaatt RRoooomm

AApppplliiccaattiioonn wwiitthh JJMMSS

Professor: Sheau-Ling Hsieh , Ph.D

Team : 9634501, Chi-Hua Chen 9634508, Chang-Min Chen

9634509, Ying-Yu Lin 9634512, Hsin-Ying Hsieh

9634519, Ming-Chia Li 9634524, Chia-Wei Hsu

9634528, Yin-Lung Lu

Institute of Information Management,

National Chiao Tung University, Hsinchu, Taiwan.

DDeevveellooppiinngg CChhaatt RRoooomm AApppplliiccaattiioonn wwiitthh JJMMSS

1

Contents

1 Introduction ..................................................................................................... 2

2 Objective .......................................................................................................... 3

3 Hardware & Software Environment............................................................... 3

3.1 Hardware................................................................................................ 3

3.2 Software.................................................................................................. 3

4 Approach(Design) ............................................................................................ 3

5 Implementation................................................................................................ 4

5.1 Common objects and functions in JMS topic ....................................... 4

5.2 Structure ................................................................................................. 5

5.3 Server Setup ........................................................................................... 6

5.4 Development Example ........................................................................... 6

6 Results (Execution) .......................................................................................... 8

7 Alternatives...................................................................................................... 9

8 Discussion and Conclusion (Problem Encountered) .....................................10

9 References .......................................................................................................11

Appendix : Source Code..........................................................................................12

Frame1.java ........................................................................................... 12

ChatManGUI.java.................................................................................. 17

ChatMan.java......................................................................................... 19

MQUtility.java ....................................................................................... 23


2

1 Introduction

The Java Message Service (JMS) API is a Java Message Oriented Middleware

(MOM) API for sending messages between two or more clients.

JMS defines an API for accessing services from a messaging provider; that is, it

is not a product itself. It is a set of interface classes that messaging provider vendors

implement. Applications that use the JMS API can then communicate with the

messaging provider the vendor supplies. The JMS API has become the industry

standard interface for Java applications to create, send, receive and read messages

using messaging providers that support the JMS API. The standard is associated with

the Java 2 Enterprise Edition (J2EE) platform. J2EE is a set of standards for a

component-based way to develop, assemble and deploy enterprise applications. J2EE

containers implement a standard runtime environment that provides quality of service

items such as security, transaction support and thread pooling.

Connection

Factory Destination

JNDI Namespace

JMS provider

Message Message

Consumer Producer

Connection::Session

JMS client

Figure 1. JMS programming model


3

In the above diagram, the JMS provider implements the JMS API. It is the entity

with which the JMS client interacts. The JMS client establishes a connection and a

session through which the interaction takes place. The JMS client establishes the

connection based on configuration information in the connection factory and

identifies where a message is to be sent to or retrieved from based on the destination.

Both the connection factory and destination objects are listed in the Java Naming

and Directory Interface (JNDI) namespace. JNDI is the Java industry standard API for

accessing naming and directory services. Since the connection factory and destination

are administered objects by JNDI, it means the JMS client can connect to different

JMS providers without changing JMS client code; that is, it creates portability. It also

means that attributes which often can and do change dynamically such as the

destination can be changed independent of the JMS client code.

2 Objective

Understand the structure of JMS in depth and use JMS to develop an example

application to describe the development process for creating distributed, object-based

applications for Java. Learn the process of middleware development, and understand

the JMS infrastructure and how it works.

3 Hardware & Software Environment

3.1 Hardware

AMD Semprom(tm) 1.00 GHz

512 MB RAM, Physical Address Extension

3.2 Software

SwiftMQ V2.1.3 (JMS Server)

4 Approach(Design)

Introduction of JMS

There are two JMS models which are showed as below,

• Point-to-point: it is a one to one model. Every message is handled by

sequence.

• Publish/Subscribe: it is a one to many models. Author can publish messages

whatever there is any subscriber.

According to above characteristic of JMS, model of Publish/Subscribe is chosen

in this project.


4

5 Implementation

5.1 Common objects and functions in JMS topic

JNDI and TopicConnectionFactory

• JNDI (Java Naming and Directory) provides application based on Java

technology with a unified interface to multiple naming and directory services.

• Property setting would not be the same in different provider JNDI.

• TopicConnectionFactory which is unable to get by JMS can be got by JNDI

• Managing connection between client and server is function of

TopicConnectionFactory.

• TopicConnection is built by TopicConnectionFactory

TopicConnection, TopicSession, and Topic

• TopicConnection represents connection between client and server.

• TopicConnections defines some methods which provide functions of

connection management, like start (), stop (), close (), etc.

• Topic Session of publishing and Topic Session of subscribing are built by

TopicConnection.

• Topic is discovered by JNDI.

• TopicPublisher and TopicSubscriber are built by TopicSession and Topic.

TopicPublisher and TopicSubscriber

• TopicPublisher, sending asynchronous messages to a specific topic at JMS

server.

• TopicSubscriber, receiving messages from a specific topic.

• There is a MessageListener which handles incoming messages in

TopicSubscriber.

• Chat class implements MessageListener.

Message

• onMessage() is one of MessageListener methods which prints out incoming

messages at Client side.

• writeMessage(), sending messages to JMS server

• TextMessage, packaging messages.

• TextMessage, there are header and string which is stored message information.


5

5.2 Structure

5.2.1 Structure is showed as below,

Figure 2. Publish/Subscribe Architecture

5.2.2 Appling the above model to multi-chat rooms,

Figure 3. Multi-Chat Rooms Architecture

(a) When someone is publishing message, he/she acts as a publisher.

On the other hand, other users act ac a Subscriber.

(b) Publisher sends his/her own message to Topic and Topic will

forward this message to online subscribers.

(c) Because of Topic just supports asynchronous messages, subscribers

have to remain online.

Publisher Subject

Subscriber

Subscriber

User 1

User 2

User 3

User 4

Topic


6

5.3 Server Setup

(a) Unzip swiftmq_2_1_3.zip to specific path.

(b) In order to starting server, running

swiftmq_2_1_3\scripts\win32\smqr1.bat at CMD.

5.4 Development Example

Jbuilder enterprise 2005 is used in following example,

(a) New project


7

(b) Imports files from swiftmq_2_1_3\swiftmq_2_1_3\jars

Files of swiftmq_2_1_3\swiftmq_2_1_3\jars

• Steps of importing files,


8

(c) Java files

6 Results (Execution)

6.1 MQUtility.java

Reading property from files, for example, Topic connection and JNDI

reference.

6.2 ChatMan.java

Implementing terminal function menu.

• Entering Account


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• Chatting

6.3 Frame1.java

Implementation chat room graphic user interface.

6.4 ChatManGUI.java

Presenting chat room graphic user interface with Java Swing.

7 Alternatives

Data Distribution Service (DDS) is an alternative to JMS. This spec was

designed and is supported by OMG (Object Management Group). The concepts are

fairly familiar to anyone who has done JMS.

DDS is newer standard based on fundamentally different paradigms than JMS,

with regards to data modeling, dataflow routing, discovery, and data typing; these

differences enable applications designers with powerful new architectural

possibilities. Despite these differences, the user experience of writing to DDS APIs


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is similar to that of JMS APIs. DDS offers several enhanced capabilities with respect

to data filtering and transformation, connectivity monitoring, redundancy and

replication, and delivery effort. DDS offers new capabilities with respect to

data-object lifecycle management, predictable delivery, delivery ordering, transport

priority, resource management, and status notifications. JMS offers some capabilities

not offered by DDS. These include client application acknowledgements, full

transaction support, message priority, and point-to-point semantics requiring a

message to be delivered to exactly one of many consumers.

8 Discussion and Conclusion (Problem

Encountered)

Most pub-sub systems we see today deal with frequently published data and tend

to provide real-time monitoring and status updates. Pub-sub is good for these kinds of

operations. Many pub-sub implementations have a peculiar limitation that makes

them only suitable for applications with frequently published data-more specifically,

applications in which it doesn't matter if you miss a message because there will be

another one in a few minutes.

The reason pub-sub usually only works in these types of applications is that

pub-sub doesn't usually have the concept of a persistent, or durable subscription. For

example, suppose you are publishing flight cancellations for LaGuardia Airport.

Although it's true that they do seem to occur often enough that there will be another

one in a few minutes, you really don't want to miss one. Now, suppose you have a

program that makes a list of passengers who need to be rebooked for the next

available flight (tomorrow, next week, sometime next year, and and so on). If the

program shuts down for a few minutes, it might miss three or four cancel lations! You

want the message server to hold on to your messages while your program is down.

JMS supports durable subscription. After you create a durable subscription, the

JMS server keeps any messages you miss while your program isn't running. To create

a durable subscription, use the createDurableSubscriber method in the TopicSession

class:

public TopicSubscriber createDurableSubscriber(Topic topic, String subscriptionName)


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You must always use the same subscription name when reconnecting your

program to its durable subscription. That is, you must always ask for subscription

name (not the topic name) when resuming that subscription. Messages can have an

expiration time, so when a message expires, the server can safely remove it from the

durable subscription. This helps keep the database size down when we you don't

resume a durable subscription for a long time.

9 References

[1] Sun Microsystems, Java Naming and Directory Interface (JNDI),

http://java.sun.com/products/jndi/

[2] O’reilly, Java Message Service(JMS),

http://www.oreilly.com

[3] IBM, Java Message Service (JMS) programming model,

http://publib.boulder.ibm.com/

[4] RTI, Data Distribution Service (DDS) and Java Message Service (JMS),

http://www.rti.com/mk/JMS.html


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Appendix : Source Code

� Frame1.java

package p5;

import javax.jms.*;

import javax.naming.*;

import java.util.*;

import java.io.*;

import java.awt.*;

import javax.swing.*;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.event.KeyEvent;

import java.awt.event.KeyAdapter;

import javax.swing.text.BadLocationException;

import javax.swing.text.StyledDocument;

import javax.swing.text.SimpleAttributeSet;

import javax.swing.text.StyleConstants;

public class Frame1 extends JFrame implements MessageListener{

String id = "default user of "+new Date();

private TopicConnection topicConnection;

private TopicSession pubSession;

private TopicSession subSession;

private TopicPublisher publisher;

private TopicSubscriber subscriber;

JPanel contentPane;

BorderLayout borderLayout1 = new BorderLayout();

JTextField jTextField1 = new JTextField();

JScrollPane jScrollPane1 = new JScrollPane();

JTextPane jTextPane1 = new JTextPane();

JPanel jPanel1 = (JPanel) getContentPane();


13

static Color red = new Color(255, 0, 0);

static Color blue = new Color(0, 0, 255);

public void sendText(String text)

{

try

{

TextMessage textMesg = pubSession.createTextMessage();

// set message property

textMesg.setStringProperty("id", id);

textMesg.setText(text);

publisher.publish(textMesg);

System.out.println(this.id+"<< "+text);

SimpleAttributeSet s1 = new SimpleAttributeSet();

StyleConstants.setForeground(s1, blue);

String CRLF = System.getProperty("line.separator");

StyledDocument doc = jTextPane1.getStyledDocument();

doc.insertString(doc.getLength(), text+CRLF, s1);

jTextPane1.setDocument(doc);

jTextField1.setText(null);

}

catch(Exception e)

{

System.out.println(e);

}

}

public void onMessage(Message mesg)

{

try

{

TextMessage textMesg = (TextMessage)mesg;

String text = textMesg.getText();

String id = textMesg.getStringProperty("id");

// only display messages from other users

if(!id.equals(this.id)) { //if

//System.out.println(id + ">> " + text);

SimpleAttributeSet s1 = new SimpleAttributeSet();

StyleConstants.setForeground(s1, red);


14

String CRLF = System.getProperty("line.separator");

StyledDocument doc = jTextPane1.getStyledDocument();

doc.insertString(doc.getLength(), id + ">> " +text+CRLF, s1);

jTextPane1.setDocument(doc);

jTextField1.setText(null);

} //if

}

catch(Exception e)

{

System.out.println(e.getMessage());

}

}

public void end() throws JMSException

{

topicConnection.close();

}

public Frame1(String id) {

this();

this.id = id;

}

public Frame1() {

try {

setDefaultCloseOperation(EXIT_ON_CLOSE);

jbInit();

} catch (Exception exception) {

exception.printStackTrace();

}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////

MQUtility mq = null;

TopicConnectionFactory topicConnectionFactory = null;

Topic topic = null;

try {

mq = new MQUtility("C:\\Documents and

Settings\\Andy\\jbproject\\andyTest0721", "mq.config");

topicConnectionFactory =


15

(TopicConnectionFactory)mq.getConnectionFactory();

topicConnection =

topicConnectionFactory.createTopicConnection();

topic = (Topic)mq.getDestination();

subSession = topicConnection.createTopicSession(false,

Session.AUTO_ACKNOWLEDGE);

pubSession = topicConnection.createTopicSession(false,


subscriber = subSession.createSubscriber(topic);

publisher = pubSession.createPublisher(topic);

subscriber.setMessageListener(this);

topicConnection.start();

} catch (Exception e) {


}

}

/**

* Component initialization.

*

* @throws java.lang.Exception

*/

private void jbInit() throws Exception {

contentPane = (JPanel) getContentPane();

contentPane.setLayout(borderLayout1);

setSize(new Dimension(400, 300));

setTitle("聊天軟體 ver. 5.0");

jTextField1.addActionListener(new

Frame1_jTextField1_actionAdapter(this));

jTextField1.addKeyListener(new

Frame1_jTextField1_keyAdapter(this));

contentPane.add(jTextField1, java.awt.BorderLayout.SOUTH);

contentPane.add(jScrollPane1, java.awt.BorderLayout.CENTER);


16

jScrollPane1.getViewport().add(jTextPane1);

}

public void jTextField1_actionPerformed(ActionEvent e) {

}

public void jTextField1_keyPressed(KeyEvent e) {

String sentence = jTextField1.getText();

if (e.getKeyCode() == 10 && !jTextField1.getText().equals(""))

{ //if

sendText(sentence);

} //if

}

}

class Frame1_jTextField1_keyAdapter extends KeyAdapter {

private Frame1 adaptee;

Frame1_jTextField1_keyAdapter(Frame1 adaptee) {

this.adaptee = adaptee;

}

public void keyPressed(KeyEvent e) {

adaptee.jTextField1_keyPressed(e);

}

}

class Frame1_jTextField1_actionAdapter implements ActionListener {

private Frame1 adaptee;

Frame1_jTextField1_actionAdapter(Frame1 adaptee) {

this.adaptee = adaptee;

}

public void actionPerformed(ActionEvent e) {

adaptee.jTextField1_actionPerformed(e);

}

}


17

� ChatManGUI.java

package p5;

import java.awt.*;

import javax.swing.*;

public class ChatManGUI {

boolean packFrame = false;

/**

* Construct and show the application.

*/

public ChatManGUI() {

Frame1 frame = new Frame1();

// Validate frames that have preset sizes

// Pack frames that have useful preferred size info, e.g. from their

layout

if (packFrame) {

frame.pack();

} else {

frame.validate();

}

// Center the window

Dimension screenSize =

Toolkit.getDefaultToolkit().getScreenSize();

Dimension frameSize = frame.getSize();

if (frameSize.height > screenSize.height) {

frameSize.height = screenSize.height;

}

if (frameSize.width > screenSize.width) {

frameSize.width = screenSize.width;

}

frame.setLocation((screenSize.width - frameSize.width) / 2,

(screenSize.height - frameSize.height) / 2);

frame.setVisible(true);


18

try {

jbInit();

} catch (Exception ex) {

ex.printStackTrace();

}

}

public ChatManGUI(String id) {

Frame1 frame = new Frame1(id);

// Validate frames that have preset sizes

// Pack frames that have useful preferred size info, e.g. from their

layout

if (packFrame) {

frame.pack();

} else {

frame.validate();

}

// Center the window

Dimension screenSize =

Toolkit.getDefaultToolkit().getScreenSize();

Dimension frameSize = frame.getSize();

if (frameSize.height > screenSize.height) {

frameSize.height = screenSize.height;

}

if (frameSize.width > screenSize.width) {

frameSize.width = screenSize.width;

}

frame.setLocation((screenSize.width - frameSize.width) / 2,

(screenSize.height - frameSize.height) / 2);

frame.setVisible(true);

try {

jbInit();



}

}


19

/**

* Application entry point.

*

* @param args String[]

*/

public static void main(String[] args) {

SwingUtilities.invokeLater(new Runnable() {

public void run() {

try {

UIManager.setLookAndFeel(UIManager.

getSystemLookAndFeelClassName());

} catch (Exception exception) {

exception.printStackTrace();

}

new ChatManGUI("bjohnlee");

}

});

}


}

}

� ChatMan.java

package p5;

import javax.jms.*;


import java.util.*;

import java.io.*;

public class ChatMan implements MessageListener {

public ChatMan() {


20

try {

jbInit();



}

}

String id;

private TopicConnection topicConnection;

private TopicSession pubSession;

private TopicSession subSession;

private TopicPublisher publisher;

private TopicSubscriber subscriber;

public ChatMan(String id) {

this.id = id;

MQUtility mq = null;

TopicConnectionFactory topicConnectionFactory = null;

Topic topic = null;

try {

mq = new MQUtility("C:\\Documents and

Settings\\Andy\\jbproject\\andyTest0721", "mq.config");

topicConnectionFactory =

(TopicConnectionFactory)mq.getConnectionFactory();

topicConnection =

topicConnectionFactory.createTopicConnection();

topic = (Topic)mq.getDestination();

subSession = topicConnection.createTopicSession(false,


pubSession = topicConnection.createTopicSession(false,


subscriber = subSession.createSubscriber(topic);

publisher = pubSession.createPublisher(topic);

subscriber.setMessageListener(this);


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topicConnection.start();



}

}

public void sendText(String text)

{

try

{

TextMessage textMesg = pubSession.createTextMessage();

// set message property

textMesg.setStringProperty("id", id);

textMesg.setText(text);

publisher.publish(textMesg);

System.out.println(this.id+"<< "+text);

}

catch(JMSException e)

{

System.out.println(e);

}

}

public void end() throws JMSException

{

topicConnection.close();

}

public void onMessage(Message mesg)

{

try

{

TextMessage textMesg = (TextMessage)mesg;

String text = textMesg.getText();

String id = textMesg.getStringProperty("id");

// only display messages from other users

if(!id.equals(this.id))


22

System.out.println(id + ">> " + text);

}

catch(JMSException e)

{


}

}

public static void main(String[] args) {

try {

System.out.println("please insert your id:");

BufferedReader reader = new BufferedReader(new

InputStreamReader(System.in));

String input = reader.readLine();

ChatMan c1 = new ChatMan(input);

input = null;

while (true) { //1

input = reader.readLine();

if (input.equals("exit")) {

System.out.println("機制結束");

System.exit(0);

} else { //2

c1.sendText(input);

} //2

} //1


System.out.println( e.getMessage() );

}

}


}

}


23

� MQUtility.java

package p5;


import java.util.*;

import java.io.*;

public class MQUtility

{

private Context jndiContext;

private String contextFactory;

private String url;

private String connectionFactory;

private String destination;

private String username;

private String password;

public MQUtility(String dir, String configFile)

throws FileNotFoundException, IOException

{

Properties mqConfig = loadConfig(dir, configFile);

url = mqConfig.getProperty("mq.url");

contextFactory = mqConfig.getProperty("mq.contextFactory");

connectionFactory = mqConfig.getProperty("mq.connectionFactory");

destination = mqConfig.getProperty("mq.destination");

username = mqConfig.getProperty("mq.username");

password = mqConfig.getProperty("mq.password");

}

public Object getConnectionFactory() throws Exception

{

return jndiLookup(connectionFactory);

}

public Object getDestination() throws Exception

{

return jndiLookup(destination);


24

}

// use initial context factory and provider URL from the configuration file

public Object jndiLookup(String name) throws NamingException

{

return jndiLookup(contextFactory, url, name);

}

// specify initial context factory and provider URL to lookup for name

public Object jndiLookup(String contextFactory, String url, String name)

throws NamingException

{

if(name == null)

throw new NamingException("Name to look up is empty");

if(jndiContext == null)

{

try

{

Properties jndiProperties = new Properties();

// initial context factory

jndiProperties.put(Context.INITIAL_CONTEXT_FACTORY,

contextFactory);

// naming server

jndiProperties.put(Context.PROVIDER_URL, url);

jndiContext = new InitialContext(jndiProperties);

}

catch(NamingException e)

{

System.out.println("Could not create JNDI context: " + url);

throw e;

}

}

Object nameObj = null;

try

{


25

nameObj = jndiContext.lookup(name);

}

catch(NamingException e)

{

System.out.println("JNDI lookup error: " + name);

throw e;

}

return nameObj;

}

public String getConnectionFactoryName()

{

if(connectionFactory != null)

connectionFactory.trim();

return connectionFactory;

}

public String getDestinationName()

{

if(destination != null)

destination.trim();

return destination;

}

public String getUsername()

{

if(username != null)

username.trim();

return username;

}

public String getPassword()

{

if(password != null)


26

password.trim();

return password;

}

// loads configurations with format like name=value from a file.

public static Properties loadConfig(String dir, String filename)

throws FileNotFoundException, IOException

{

File inFile = null;

Properties prop = null;

inFile = new File(dir, filename);

if(inFile.exists())

{

prop = new Properties();

prop.load(new FileInputStream(inFile));

}

else

throw new FileNotFoundException("Can not find '" +

inFile.toString() + "'");

return prop;

}

public void close() throws NamingException

{

jndiContext.close();

}

}

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