Demonstrates the use of transactions in a JMS application : Java Message Service JMS « J2EE « Java

Java
1. 2D Graphics GUI
2. 3D
3. Advanced Graphics
4. Ant
5. Apache Common
6. Chart
7. Class
8. Collections Data Structure
9. Data Type
10. Database SQL JDBC
11. Design Pattern
12. Development Class
13. EJB3
14. Email
15. Event
16. File Input Output
17. Game
18. Generics
19. GWT
20. Hibernate
21. I18N
22. J2EE
23. J2ME
24. JDK 6
25. JNDI LDAP
26. JPA
27. JSP
28. JSTL
29. Language Basics
30. Network Protocol
31. PDF RTF
32. Reflection
33. Regular Expressions
34. Scripting
35. Security
36. Servlets
37. Spring
38. Swing Components
39. Swing JFC
40. SWT JFace Eclipse
41. Threads
42. Tiny Application
43. Velocity
44. Web Services SOA
45. XML
Java Tutorial
Java Source Code / Java Documentation
Java Open Source
Jar File Download
Java Articles
Java Products
Java by API
Photoshop Tutorials
Maya Tutorials
Flash Tutorials
3ds-Max Tutorials
Illustrator Tutorials
GIMP Tutorials
C# / C Sharp
C# / CSharp Tutorial
C# / CSharp Open Source
ASP.Net
ASP.NET Tutorial
JavaScript DHTML
JavaScript Tutorial
JavaScript Reference
HTML / CSS
HTML CSS Reference
C / ANSI-C
C Tutorial
C++
C++ Tutorial
Ruby
PHP
Python
Python Tutorial
Python Open Source
SQL Server / T-SQL
SQL Server / T-SQL Tutorial
Oracle PL / SQL
Oracle PL/SQL Tutorial
PostgreSQL
SQL / MySQL
MySQL Tutorial
VB.Net
VB.Net Tutorial
Flash / Flex / ActionScript
VBA / Excel / Access / Word
XML
XML Tutorial
Microsoft Office PowerPoint 2007 Tutorial
Microsoft Office Excel 2007 Tutorial
Microsoft Office Word 2007 Tutorial
Java » J2EE » Java Message Service JMSScreenshots 
Demonstrates the use of transactions in a JMS application
 

/*
 * @(#)TransactedExample.java  1.4 04/09/15
 *
 * Copyright (c) 2000-2002 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
 * modify and redistribute this software in source and binary code form,
 * provided that i) this copyright notice and license appear on all copies of
 * the software; and ii) Licensee does not utilize the software in a manner
 * which is disparaging to Sun.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
 * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
 * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
 * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
 * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
 * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
 * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
 * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * This software is not designed or intended for use in on-line control of
 * aircraft, air traffic, aircraft navigation or aircraft communications; or in
 * the design, construction, operation or maintenance of any nuclear
 * facility. Licensee represents and warrants that it will not use or
 * redistribute the Software for such purposes.
 */
import java.util.Random;
import java.util.Hashtable;
import javax.jms.Queue;
import javax.jms.Session;
import javax.jms.ConnectionFactory;
import javax.jms.Connection;
import javax.jms.MessageProducer;
import javax.jms.MessageConsumer;
import javax.jms.Message;
import javax.jms.MapMessage;
import javax.jms.MessageListener;
import javax.jms.JMSException;

/**
 * The TransactedExample class demonstrates the use of transactions in a JMS
 * application.  It represents a highly simplified eCommerce application, in
 * which the following things happen:
 *
 * <pre>
 * Legend
 * R - Retailer
 * V - Vendor
 * S - Supplier
 * O - Order Queue
 * C - Confirmation Queue
 * ()- Thread
 * []- Queue
 *
 *                                   2(b)             3
 *          1        2(a)        /+------->[S1 O]<-----------(S1)
 *        /+-->[V O]<----+      /                             |
 *       /                \    /                      3       |
 *      /                  \  /     5      v------------------+
 *    (R)                  ( V )-------->[V C]        4
 *     \                   /  \            ^------------------+
 *      \                 /    \                              |
 *       \   7         6 /      \                             |
 *        +---->[R C]<--+        \   2(c)             4       |
 *                                +------->[SN O]<-----------(SN)
 * </pre>
 *
 * <ol>
 * <li>A retailer sends a message to the vendor order queue ordering a quantity 
 * of computers.  It waits for the vendor's reply.
 * <li>The vendor receives the retailer's order message and places an order 
 * message into each of its suppliers' order queues, all in one transaction. 
 * This JMS transaction combines one synchronous receive with multiple sends.
 * <li>One supplier receives the order from its order queue, checks its
 * inventory, and sends the items ordered to the order message's replyTo
 * field. If it does not have enough in stock, it sends what it has. 
 * The synchronous receive and the send take place in one JMS transaction.
 * <li>The other supplier receives the order from its order queue, checks its
 * inventory, and sends the items ordered to the order message's replyTo
 * field. If it does not have enough in stock, it sends what it has. 
 * The synchronous receive and the send take place in one JMS transaction.
 * <li>The vendor receives the replies from the suppliers from its confirmation 
 * queue and updates the state of the order.  Messages are processed by an 
 * asynchronous message listener; this step illustrates using JMS transactions 
 * with a message listener.
 * <li>When all outstanding replies are processed for a given order, the vendor 
 * sends a message notifying the retailer whether or not it can fulfill the 
 * order.
 * <li>The retailer receives the message from the vendor.
 * </ol>
 * <p>
 * The program contains five classes: Retailer, Vendor, GenericSupplier, 
 * VendorMessageListener, and Order.  It also contains a main method and a 
 * method that runs the threads of the Retail, Vendor, and two supplier classes.
 * <p>
 * All the messages use the MapMessage message type.  Synchronous receives are
 * used for all message reception except for the case of the vendor processing 
 * the replies of the suppliers. These replies are processed asynchronously 
 * and demonstrate how to use transactions within a message listener.
 * <p>
 * All classes except Retailer use transacted sessions.
 * <p>
 * The program uses five queues.  Before you run the program, create the
 * queues and name them A, B, C, D and E.
 * <p>
 * When you run the program, specify on the command line the number of
 * computers to be ordered.
 *
 @author Kim Haase
 @author Joseph Fialli
 @version 1.3, 08/18/00
 */
public class TransactedExample {
    public static String  vendorOrderQueueName = null;
    public static String  retailerConfirmationQueueName = null;
    public static String  monitorOrderQueueName = null;
    public static String  storageOrderQueueName = null;
    public static String  vendorConfirmationQueueName = null;
    public static int     exitResult = 0;

    /**
     * The Retailer class orders a number of computers by sending a message
     * to a vendor.  It then waits for the order to be confirmed.
     * <p>
     * In this example, the Retailer places two orders, one for the quantity
     * specified on the command line and one for twice that number.
     * <p>
     * This class does not use transactions.
     *
     @author Kim Haase
     @author Joseph Fialli
     @version 1.3, 08/18/00
     */
    public static class Retailer extends Thread {
        int  quantity = 0;

        /**
         * Constructor.  Instantiates the retailer with the quantity of 
         * computers being ordered.
         *
         @param q  the quantity specified in the program arguments
         */
        public Retailer(int q) {
            quantity = q;
        }

        /**
         * Runs the thread.
         */
        public void run() {
            ConnectionFactory    connectionFactory = null;
            Connection           connection = null;
            Session              session = null;
            Queue                vendorOrderQueue = null;
            Queue                retailerConfirmationQueue = null;
            MessageProducer      msgProducer = null;
            MapMessage           outMessage = null;
            MessageConsumer      orderConfirmationConsumer = null;
            MapMessage           inMessage = null;

            try {
                connectionFactory =
                    SampleUtilities.getConnectionFactory();
                connection =
                    connectionFactory.createConnection();
                session = connection.createSession(false,
                                                     Session.AUTO_ACKNOWLEDGE);
                vendorOrderQueue =
                    SampleUtilities.getQueue(vendorOrderQueueName, session);
                retailerConfirmationQueue =
                    SampleUtilities.getQueue(retailerConfirmationQueueName, 
                                             session);
            catch (Exception e) {
                System.out.println("Connection problem: " + e.toString());
                System.out.println("Program assumes five queues named A B C D E");
                if (connection != null) {
                    try {
                        connection.close();
                    catch (JMSException ee) {}
                }
                System.exit(1);
            }

            /*
             * Create non-transacted session and sender for vendor order
             * queue.
             * Create message to vendor, setting item and quantity values.
             * Send message.
             * Create receiver for retailer confirmation queue.
             * Get message and report result.
             * Send an end-of-message-stream message so vendor will
             * stop processing orders.
             */
            try {
                msgProducer = session.createProducer(vendorOrderQueue);
                outMessage = session.createMapMessage();
                outMessage.setString("Item""Computer(s)");
                outMessage.setInt("Quantity", quantity);
                outMessage.setJMSReplyTo(retailerConfirmationQueue);
                msgProducer.send(outMessage);
                System.out.println("Retailer: ordered " + quantity
                                   " computer(s)");

                orderConfirmationConsumer =
                    session.createConsumer(retailerConfirmationQueue);
                connection.start();
                inMessage = (MapMessageorderConfirmationConsumer.receive();
                if (inMessage.getBoolean("OrderAccepted"== true) {
                    System.out.println("Retailer: Order filled");
                else {
                    System.out.println("Retailer: Order not filled");
                }
                
                
                System.out.println("Retailer: placing another order");
                outMessage.setInt("Quantity", quantity * 2);
                msgProducer.send(outMessage);
                System.out.println("Retailer: ordered " 
                                   + outMessage.getInt("Quantity")
                                   " computer(s)");
                inMessage =
                    (MapMessageorderConfirmationConsumer.receive();
                if (inMessage.getBoolean("OrderAccepted"== true) {
                    System.out.println("Retailer: Order filled");
                else {
                    System.out.println("Retailer: Order not filled");
                }

                // Send a non-text control message indicating end of messages.
                msgProducer.send(session.createMessage());
            catch (Exception e) {
                System.out.println("Retailer: Exception occurred: " 
                                   + e.toString());
                e.printStackTrace();
                exitResult = 1;
            finally {
                if (connection != null) {
                    try {
                        connection.close();
                    catch (JMSException e) {
                        exitResult = 1;
                    }
                }
            }
        }
    }

    /**
     * The Vendor class uses one transaction to receive the computer order from
     * the retailer and order the needed number of monitors and disk drives
     * from its suppliers.  At random intervals, it throws an exception to
     * simulate a database problem and cause a rollback.
     * <p>
     * The class uses an asynchronous message listener to process replies from
     * suppliers. When all outstanding supplier inquiries complete, it sends a 
     * message to the Retailer accepting or refusing the order.
     *
     @author Kim Haase
     @author Joseph Fialli
     @version 1.3, 08/18/00
     */
    public static class Vendor extends Thread {
        Random  rgen = new Random();
        int     throwException = 1;

        /**
         * Runs the thread.
         */
        public void run() {
            ConnectionFactory        connectionFactory = null;
            Connection               connection = null;
            Session                  session = null;
            Session                  asyncSession = null;
            Queue                    vendorOrderQueue = null;
            Queue                    monitorOrderQueue = null;
            Queue                    storageOrderQueue = null;
            Queue                    vendorConfirmationQueue = null;
            MessageConsumer          vendorOrderMessageConsumer = null;
            MessageProducer          monitorOrderMessageProducer = null;
            MessageProducer          storageOrderMessageProducer = null;
            MapMessage               orderMessage = null;
            MessageConsumer          vendorConfirmationMessageConsumer = null;
            VendorMessageListener    listener = null;
            Message                  inMessage = null;
            MapMessage               vendorOrderMessage = null;
            Message                  endOfMessageStream = null;
            Order                    order = null;
            int                      quantity = 0;

            try {
                connectionFactory =
                    SampleUtilities.getConnectionFactory();
                connection =
                    connectionFactory.createConnection();
                session = connection.createSession(true, 0);
                asyncSession = connection.createSession(true, 0);
                vendorOrderQueue =
                    SampleUtilities.getQueue(vendorOrderQueueName, session);
                monitorOrderQueue =
                    SampleUtilities.getQueue(monitorOrderQueueName, session);
                storageOrderQueue =
                    SampleUtilities.getQueue(storageOrderQueueName, session);
                vendorConfirmationQueue =
                    SampleUtilities.getQueue(vendorConfirmationQueueName, session);
            catch (Exception e) {
                System.out.println("Connection problem: " + e.toString());
                System.out.println("Program assumes six queues named A B C D E F");
                if (connection != null) {
                    try {
                        connection.close();
                    catch (JMSException ee) {}
                }
                System.exit(1);
            }

            try {
                /*
                 * Create receiver for vendor order queue, sender for
                 * supplier order queues, and message to send to suppliers.
                 */
                vendorOrderMessageConsumer = 
                    session.createConsumer(vendorOrderQueue);
                monitorOrderMessageProducer = 
                    session.createProducer(monitorOrderQueue);
                storageOrderMessageProducer = 
                    session.createProducer(storageOrderQueue);
                orderMessage = session.createMapMessage();

                /*
                 * Configure an asynchronous message listener to process
                 * supplier replies to inquiries for parts to fill order.
                 * Start delivery.
                 */
                vendorConfirmationMessageConsumer = 
                    asyncSession.createConsumer(vendorConfirmationQueue);
                listener = new VendorMessageListener(asyncSession, 2);
                vendorConfirmationMessageConsumer.setMessageListener(listener);
                connection.start();

                /*
                 * Process orders in vendor order queue.
                 * Use one transaction to receive order from order queue
                 * and send messages to suppliers' order queues to order 
                 * components to fulfill the order placed with the vendor.
                 */
                while (true) {
                    try {

                        // Receive an order from a retailer.
                        inMessage = vendorOrderMessageConsumer.receive();
                        if (inMessage instanceof MapMessage) {
                            vendorOrderMessage = (MapMessageinMessage;
                        else {
                            /*
                             * Message is an end-of-message-stream message from
                             * retailer.  Send similar messages to suppliers,
                             * then break out of processing loop.
                             */
                            endOfMessageStream = session.createMessage();
                            endOfMessageStream.setJMSReplyTo(vendorConfirmationQueue);
                            monitorOrderMessageProducer.send(endOfMessageStream);
                            storageOrderMessageProducer.send(endOfMessageStream);
                            session.commit();
                            break;
                        }

                        /*
                         * A real application would check an inventory database
                         * and order only the quantities needed.  Throw an
                         * exception every few times to simulate a database
                         * concurrent-access exception and cause a rollback.
                         */
                        if (rgen.nextInt(3== throwException) {
                            throw new JMSException("Simulated database concurrent access exception");
                        }

                        // Record retailer order as a pending order.
                        order = new Order(vendorOrderMessage);
                        
                        /*
                         * Set order number and reply queue for outgoing
                         * message.
                         */
                        orderMessage.setInt("VendorOrderNumber"
                                            order.orderNumber);
                        orderMessage.setJMSReplyTo(vendorConfirmationQueue);
                        quantity = vendorOrderMessage.getInt("Quantity");
                        System.out.println("Vendor: Retailer ordered " +
                                           quantity + " " +
                                           vendorOrderMessage.getString("Item"));

                        // Send message to monitor supplier.
                        orderMessage.setString("Item""Monitor");
                        orderMessage.setInt("Quantity", quantity);
                        monitorOrderMessageProducer.send(orderMessage);
                        System.out.println("Vendor: ordered " + quantity + " " 
                                           + orderMessage.getString("Item"
                                           "(s)");

                        /*
                         * Reuse message to send to storage supplier, changing
                         * only item name.
                         */
                        orderMessage.setString("Item""Hard Drive");
                        storageOrderMessageProducer.send(orderMessage);
                        System.out.println("Vendor: ordered " + quantity + " " 
                                           + orderMessage.getString("Item"
                                           "(s)");

                        // Commit session.
                        session.commit();
                        System.out.println("  Vendor: committed transaction 1");
                    catch(JMSException e) {
                        System.out.println("Vendor: JMSException occurred: "
                            + e.toString());
                        e.printStackTrace();
                        session.rollback();
                        System.out.println("  Vendor: rolled back transaction 1");
                        exitResult = 1;
                    }
                }

                // Wait till suppliers get back with answers.
                listener.monitor.waitTillDone();
            catch (JMSException e) {
                System.out.println("Vendor: Exception occurred: " +
                                   e.toString());
                e.printStackTrace();
                exitResult = 1;
            finally {
                if (connection != null) {
                    try {
                        connection.close();
                    catch (JMSException e) {
                        exitResult = 1;
                    }
                }
            }
        }
    }

    /**
     * The Order class represents a Retailer order placed with a Vendor.
     * It maintains a table of pending orders.
     *
     @author Joseph Fialli
     @version 1.3, 08/18/00
     */
    public static class Order {
        private static Hashtable  pendingOrders = new Hashtable();
        private static int        nextOrderNumber = 1;

        private static final int  PENDING_STATUS   = 1;
        private static final int  CANCELLED_STATUS = 2;
        private static final int  FULFILLED_STATUS = 3;
        int                       status;

        public final int          orderNumber;
        public int                quantity;
        public final MapMessage   order;   // original order from retailer
        public MapMessage         monitor = null;  // reply from supplier
        public MapMessage         storage = null;  // reply from supplier

        /**
         * Returns the next order number and increments the static variable
         * that holds this value.
         *
         @return  the next order number
         */
        private static int getNextOrderNumber() {
            int  result = nextOrderNumber;
            nextOrderNumber++;
            return result;
        }

        /**
         * Constructor.  Sets order number; sets order and quantity from  
         * incoming message. Sets status to pending, and adds order to hash 
         * table of pending orders.
         *
         @param order  the message containing the order
         */
        public Order(MapMessage order) {
            this.orderNumber = getNextOrderNumber();
            this.order = order;
            try {
                this.quantity = order.getInt("Quantity");
            catch (JMSException je) {
                System.err.println("Unexpected error. Message missing Quantity");
                this.quantity = 0;
            }
            status = PENDING_STATUS;
            pendingOrders.put(new Integer(orderNumber)this);
        }

        /**
         * Returns the number of orders in the hash table.
         *
         @return  the number of pending orders
         */
        public static int outstandingOrders() {
            return pendingOrders.size();
        }

        /**
         * Returns the order corresponding to a given order number.
         *
         @param orderNumber  the number of the requested order
         @return  the requested order
         */
        public static Order getOrder(int orderNumber) {
            return (OrderpendingOrders.get(new Integer(orderNumber));
        }

        /**
         * Called by the onMessage method of the VendorMessageListener class
         * to process a reply from a supplier to the Vendor.
         *
         @param component  the message from the supplier
         @return  the order with updated status information
         */
        public Order processSubOrder(MapMessage component) {
            String  itemName = null;

            // Determine which subcomponent this is.
            try {
                itemName = component.getString("Item");
            catch (JMSException je) {
                System.err.println("Unexpected exception. Message missing Item");
            }
            if (itemName.compareTo("Monitor"== 0) {
                monitor = component;
            else if (itemName.compareTo("Hard Drive"== ) {
                storage = component;
            }

            /*
             * If notification for all subcomponents has been received,
             * verify the quantities to compute if able to fulfill order.
             */
            if ( (monitor != null&& (storage != null) ) {
                try {
                    if (quantity > monitor.getInt("Quantity")) {
                        status = CANCELLED_STATUS;
                    else if (quantity > storage.getInt("Quantity")) {
                        status = CANCELLED_STATUS;
                    else {
                        status = FULFILLED_STATUS;
                    }
                catch (JMSException je) {
                    System.err.println("Unexpected exception " + je);
                    status = CANCELLED_STATUS;
                }

                /*
                 * Processing of order is complete, so remove it from 
                 * pending-order list.
                 */
                pendingOrders.remove(new Integer(orderNumber));
            }
            return this;
        }

        /**
         * Determines if order status is pending.
         *
         @return  true if order is pending, false if not
         */
        public boolean isPending() {
            return status == PENDING_STATUS;
        }

        /**
         * Determines if order status is cancelled.
         *
         @return  true if order is cancelled, false if not
         */
        public boolean isCancelled() {
            return status == CANCELLED_STATUS;
        }

        /**
         * Determines if order status is fulfilled.
         *
         @return  true if order is fulfilled, false if not
         */
        public boolean isFulfilled() {
            return status == FULFILLED_STATUS;
        }
    }

    /**
     * The VendorMessageListener class processes an order confirmation message
     * from a supplier to the vendor.
     * <p>
     * It demonstrates the use of transactions within message listeners.
     *
     @author Joseph Fialli
     @version 1.3, 08/18/00
     */
    public static class VendorMessageListener implements MessageListener {
        final SampleUtilities.DoneLatch  monitor =
            new SampleUtilities.DoneLatch();
        private final Session session;
        int numSuppliers;

        /**
         * Constructor.  Instantiates the message listener with the session
         * of the consuming class (the vendor).
         *
         @param session   the session of the consumer
         @param numSuppliers  the number of suppliers
         */
        public VendorMessageListener(Session session, int numSuppliers) {
            this.session = session;
            this.numSuppliers = numSuppliers;
        }

        /**
         * Casts the message to a MapMessage and processes the order.
         * A message that is not a MapMessage is interpreted as the end of the  
         * message stream, and the message listener sets its monitor state to  
         * all done processing messages.
         * <p>
         * Each message received represents a fulfillment message from
         * a supplier.
         *
         @param message  the incoming message
         */
        public void onMessage(Message message) {

            /*
             * If message is an end-of-message-stream message and this is the
             * last such message, set monitor status to all done processing 
             * messages and commit transaction.
             */
            if ((message instanceof MapMessage)) {
                if (Order.outstandingOrders() == 0) {
                    numSuppliers--;
                    if (numSuppliers == 0) {
              monitor.allDone();
          }
                }
                try {
                    session.commit();
                catch (JMSException je) {}
                return;
            }

            /* 
             * Message is an order confirmation message from a supplier.
             */
            int orderNumber = -1;
            try {
                MapMessage component = (MapMessagemessage;

                /* 
                 * Process the order confirmation message and commit the
                 * transaction.
                 */
                orderNumber = component.getInt("VendorOrderNumber");
                Order order = 
                    Order.getOrder(orderNumber).processSubOrder(component);
                session.commit();
                
                /*
                 * If this message is the last supplier message, send message
                 * to Retailer and commit transaction.
                 */
                if (! order.isPending()) {
                    System.out.println("Vendor: Completed processing for order "
                        + order.orderNumber);
                    Queue replyQueue = (Queueorder.order.getJMSReplyTo();
                    MessageProducer mp = session.createProducer(replyQueue);
                    MapMessage retailerConfirmationMessage = 
                        session.createMapMessage();
                    if (order.isFulfilled()) {
                        retailerConfirmationMessage.setBoolean("OrderAccepted"
                                                               true);
                        System.out.println("Vendor: sent " + order.quantity
                                           " computer(s)");
                    else if (order.isCancelled()) {
                        retailerConfirmationMessage.setBoolean("OrderAccepted"
                                                               false);
                        System.out.println("Vendor: unable to send " +
                                           order.quantity + " computer(s)");
                    }
                    mp.send(retailerConfirmationMessage);
                    session.commit();
                    System.out.println("  Vendor: committed transaction 2");
                }
            catch (JMSException je) {
                je.printStackTrace();
                try {
                    session.rollback();
                catch (JMSException je2) {}
            catch (Exception e) {
                e.printStackTrace();
                try {
                    session.rollback();
                catch (JMSException je2) {}
            }
        }
    }

    /**
     * The GenericSupplier class receives an item order from the
     * vendor and sends a message accepting or refusing it.
     *
     @author Kim Haase
     @author Joseph Fialli
     @version 1.3, 08/18/00
     */
    public static class GenericSupplier extends Thread {
        final String  PRODUCT_NAME;
        final String  IN_ORDER_QUEUE;
        int           quantity = 0;

        /**
         * Constructor.  Instantiates the supplier as the supplier for the
         * kind of item being ordered.
         *
         @param itemName  the name of the item being ordered
         @param inQueue  the queue from which the order is obtained
         */
        public GenericSupplier(String itemName, String inQueue) {
            PRODUCT_NAME = itemName;
            IN_ORDER_QUEUE = inQueue;
        }

        /**
         * Checks to see if there are enough items in inventory.
         * Rather than go to a database, it generates a random number related
         * to the order quantity, so that some of the time there won't be
         * enough in stock.
         *
         @return  the number of items in inventory
         */
        public int checkInventory() {
            Random  rgen = new Random();

            return (rgen.nextInt(quantity * 5));
        }

        /**
         * Runs the thread.
         */
        public void run() {
            ConnectionFactory    connectionFactory = null;
            Connection           connection = null;
            Session              session = null;
            Queue                orderQueue = null;
            MessageConsumer      msgConsumer = null;
            Message              inMessage = null;
            MapMessage           orderMessage = null;
            MapMessage           outMessage = null;

            try {
                connectionFactory =
                    SampleUtilities.getConnectionFactory();
                connection =
                    connectionFactory.createConnection();
                session = connection.createSession(true, 0);
                orderQueue =
                    SampleUtilities.getQueue(IN_ORDER_QUEUE, session);
            catch (Exception e) {
                System.out.println("Connection problem: " + e.toString());
                System.out.println("Program assumes six queues named A B C D E F");
                if (connection != null) {
                    try {
                        connection.close();
                    catch (JMSException ee) {}
                }
                System.exit(1);
            }
            
            // Create receiver for order queue and start message delivery.
            try {
                msgConsumer = session.createConsumer(orderQueue);
                connection.start();
            catch (JMSException je) {
                exitResult = 1;
            }

            /*
             * Keep checking supplier order queue for order request until
             * end-of-message-stream message is received.
             * Receive order and send an order confirmation as one transaction.
             */
            while (true) {
                try {
                    inMessage = msgConsumer.receive();
                    if (inMessage instanceof MapMessage) {
                        orderMessage = (MapMessageinMessage;
                    else {
                        /*
                         * Message is an end-of-message-stream message.
                         * Send a similar message to reply queue, commit
                         * transaction, then stop processing orders by breaking
                         * out of loop.
                         */
                        MessageProducer msgProducer =
                            session.createProducer((QueueinMessage.getJMSReplyTo());
                        msgProducer.send(session.createMessage());
                        session.commit();
                        break;
                    }

                    // Extract quantity ordered from order message.
                    quantity = orderMessage.getInt("Quantity");
                    System.out.println(PRODUCT_NAME 
                        " Supplier: Vendor ordered " + quantity + " " 
                        + orderMessage.getString("Item""(s)");

                    /*
                     * Create sender and message for reply queue.
                     * Set order number and item; check inventory and set
                     * quantity available.  
                     * Send message to vendor and commit transaction.
                     */
                    MessageProducer msgProducer =
                        session.createProducer((QueueorderMessage.getJMSReplyTo());
                    outMessage = session.createMapMessage();
                    outMessage.setInt("VendorOrderNumber",
                                      orderMessage.getInt("VendorOrderNumber"));
                    outMessage.setString("Item", PRODUCT_NAME);
                    int numAvailable = checkInventory();
                    if (numAvailable >= quantity) {
                        outMessage.setInt("Quantity", quantity);
                    else {
                        outMessage.setInt("Quantity", numAvailable);
                    }
                    msgProducer.send(outMessage);
                    System.out.println(PRODUCT_NAME + " Supplier: sent "
                                       + outMessage.getInt("Quantity"" " 
                                       + outMessage.getString("Item""(s)");
                    session.commit();
                    System.out.println("  " + PRODUCT_NAME
                                       " Supplier: committed transaction");
                catch (Exception e) {
                    System.out.println(PRODUCT_NAME 
                        " Supplier: Exception occurred: " + e.toString());
                    e.printStackTrace();
                    exitResult = 1;
                
            }

            if (connection != null) {
                try {
                    connection.close();
                catch (JMSException e) {
                    exitResult = 1;
                }
            }
        }
    }

    /**
     * Creates the Retailer and Vendor classes and the two supplier classes,
     * then starts the threads.
     *
     @param quantity  the quantity specified on the command line
     */
    public static void run_threads(int quantity) {
        Retailer         r = new Retailer(quantity);
        Vendor           v = new Vendor();
        GenericSupplier  ms = new GenericSupplier("Monitor"
                                                 monitorOrderQueueName);
        GenericSupplier  ss = new GenericSupplier("Hard Drive"
                                                 storageOrderQueueName);

        r.start();
        v.start();
        ms.start();
        ss.start();
        try {
            r.join();
            v.join();
            ms.join();
            ss.join();
        catch (InterruptedException e) {}
    }

    /**
     * Reads the order quantity from the command line, then
     * calls the run_threads method to execute the program threads.
     *
     @param args  the quantity of computers being ordered
     */
    public static void main(String[] args) {
        TransactedExample  te = new TransactedExample();
        int                quantity = 0;

        if (args.length != 1) {
            System.out.println("Usage: java TransactedExample <integer>");
            System.out.println("Program assumes five queues named A B C D E");
            System.exit(1);
        }
        te.vendorOrderQueueName = new String("A");
        te.retailerConfirmationQueueName = new String("B");
        te.monitorOrderQueueName = new String("C");
        te.storageOrderQueueName = new String("D");
        te.vendorConfirmationQueueName = new String("E");
        quantity = (new Integer(args[0])).intValue();
        System.out.println("Quantity to be ordered is " + quantity);
        if (quantity > 0) {
            te.run_threads(quantity);
        else {
            System.out.println("Quantity must be positive and nonzero");
            te.exitResult = 1;
        }
        SampleUtilities.exit(te.exitResult);
    }
}

        
jms.zip( 65 k)
Related examples in the same category
1. The mqping utility is similar to the Unix ping utility in some regards
2. This example illustrates how JMS (Java Message Service) API can be used in a Java applet
3. This example illustrates how JMS can be used to create a simple chat application
4. The UniversalClient example is a basic 'client' application that uses the JMS 1.1 APIs
5. How to write a GUI application that uses a JMS QueueBrowser to browse the contents of a queue
6. This example is a simple JMS client application
7. Demonstrates a simple end-to-end "Hello World" JMS example that can be compiled and run with the Sun Java(tm) System Message Queue product
8. The BrokerMetrics example is a JMS application that monitors the Sun Java(tm) System Message Queue broker
9. The DestListMetrics example is a JMS application that monitors the destinations on a Sun Java(tm) System Message Queue broker
10. The DestMetrics example is a JMS application that monitors a destination on a Sun Java(tm) System Message Queue broker
11. The VMMetrics example is a JMS application that monitors the Java VM used by the Sun Java(tm) System Message Queue broker
12. MQ Cluster Monitor
13. The TopicSelectors class demonstrates the use of multiple subscribers and message selectors
14. A message will not be acknowledged until processing of it is complete
15. Reads a textfile, creates a BytesMessage from it, then reads the message
16. A durable subscription is active even when the subscriber is not active
17. Creates and then reads a StreamMessage and a BytesMessage
18. Creates and reads messages in all supported JMS message formats: BytesMessage, TextMessage, MapMessage, StreamMessage, and ObjectMessage
19. The use of message header fields
20. Demonstrates that mutable objects are copied, not passed by reference, when you use them to create message objects
21. A simple implementation of a request/reply message exchange
22. Sends several messages to a queue
23. Fetches one or more messages from a queue using synchronous message delivery
24. The simplest form of the publish/subscribe model: the producer publishes a message, and the consumer reads it using a synchronous receive
25. Creates a Producer and a Consumer objects (Producer and Consumer classes are defined in this file)
26. Fetches one or more messages from a queue using asynchronous message delivery
27. The use of a message listener in the publish/subscribe model. The producer publishes several messages, and the consumer reads them asynchronously
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.