Sams Teach Yourself BEA WebLogic Server 7.0 in 21 Days

The architecture of the restaurant example system now works as follows:

  1. The Customer instantiates a Waiter object.

  2. The Customer then gets the menu list and orders the items.

  3. On calling the method to confirm the order, the Waiter loops through the vector of ordered items and allocates each item to a Chef from the Chef bean pool. The Waiter then calls a static method called getAllCookedItems()method of the ReceiveMessagesFromQueue class, which is described a little later.

  4. The Chef creates the items after looking up the ingredients in the Item bean pool.

  5. After creating the cooked items, the Chef puts the cooked items into the Message queue "ORDERED_ITEMS_QUEUE".

  6. The ReceiveMessagesFromQueue class receives the items and puts them into a vector. In this class the method getAllCookedItems() keeps checking whether the items received are equal to the items sent to be cooked. When they are equal, the cooked-items vector is sent back to the waiter.

  7. The Customer now calls the method serveCookedItem()on the Waiter.

  8. The Waiter serves the items by returning a Vector of cooked items.

  9. The Customer asks for the bill by calling the getCheck() method on the Waiter. The Waiter delivers the bill.

The code in Listings 15.1 through 15.4 implements messaging; only the classes that have been added or changed are shown. Two classes have changed:

  • WaiterBean.java

  • ChefBean.java

The classes that have been added are

  • SendMessagesToQueue.java

  • eceiveMessagesFromQueue.java

Listing 15.1 WaiterBean.java

/****************************************************************************** * Class Name : WaiterBean.java * Description : Picks Chef from Chef pool, passes the ordered items to the * Chef and gets the cooked items. Then serves the client. * @author Mandar S. Chitnis, Lakshmi AM. @version 1.3 * Copyright (c) by Sams Publishing. All Rights Reserved. *******************************************************************************/ package com.sams.learnweblogic7.ejb.jms; import java.util.*; import java.rmi.RemoteException; import java.util.Properties; import javax.ejb.CreateException; import javax.ejb.RemoveException; import javax.naming.*; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; import javax.rmi.PortableRemoteObject; import javax.ejb.*; public class WaiterBean implements SessionBean { //defining private and public variables, for the list of items ordered //by client, and items cooked by chef private Vector orderedItemsList = new Vector(); private Vector cookedItems = new Vector(); private static final String CHEFHOME_JNDI_NAME = "Chef_Home"; private static final boolean ENABLE_WEBLOGIC_LOGGING = true; private SessionContext ctx; // Using WebLogic's log service to log events private void webLogicLog(String logMessage) { if (ENABLE_WEBLOGIC_LOGGING) System.out.println(logMessage); } //end of webLogicLog /** * Per EJB specifications to be implemented by bean, * Used when create is called on the remote interface */ public void ejbCreate() { webLogicLog("Method ejbCreate has been called"); } /** * Per EJB specifications to be implemented by bean, * Presently not being used */ public void ejbActivate() { webLogicLog("Method ejbActivate has been called"); }//end of ejbActivate /** * Per EJB specifications to be implemented by bean, * Presently not being used */ public void ejbRemove() { webLogicLog("Method ejbRemove has been called"); }//end of ejbRemove /** * Per EJB specifications to be implemented by bean, * Presently not being used */ public void ejbPassivate() { webLogicLog("Method ejbPassivate has been called"); }//end of ejbPassivate /** * Sets the session context. * * @param ctx SessionContext Context for session */ public void setSessionContext(SessionContext ctx) { webLogicLog("Method setSessionContext has been called"); this.ctx = ctx; }//end of setSessionContext //method called by client to get a list of Menu items. public MenuList getMenu(){ return MenuList.getMenu(); } //method called by client to get the order. //The client gets the menu item id from the menu list, and also //specifies the number of items. public void getOrder(MenuItem orderedItem, int quantity){ System.out.println("Item ordered : "+orderedItem.getItemDesc()); System.out.println("Item qty ordered : "+quantity); orderedItemsList.addElement(new Order(orderedItem, quantity)); } //the client calls this method to confirm his order. //When he does this, the waiter requests for an available chef //from the chef pool, and sends the item to be prepared to the chef. // The chef returns the cooked item. // The waiter then collects all the cooked items into his tray // (the global vector) and returns the cook to the cook pool public void confirmOrder(){ CookedItemImpl currentCookedItem; int itemsOrderedCtr = 0; MenuItem menuItemToBeProcessed; Enumeration orderedItemsEnum = orderedItemsList.elements(); while(orderedItemsEnum.hasMoreElements()) { try{ ChefInterface currentChef = getChefFromChefPool(); menuItemToBeProcessed = ((Order)orderedItemsEnum.nextElement()). getItem(); itemsOrderedCtr++; //currentCookedItem = currentChef.cookItem(menuItemToBeProcessed); //cookedItems.addElement(currentCookedItem); } catch(Exception e){ e.printStackTrace(); } }//end of while //calling the static method cookedItems = ReceiveMessagesFromQueue.getAllCookedItems (itemsOrderedCtr); } //called by the waiter to get a chef from the chef pool public ChefInterface getChefFromChefPool(){ ChefInterface chef=null; try{ ChefHome chefHome = lookupHome(); chef = (ChefInterface)PortableRemoteObject.narrow(chefHome.create(),ChefInterface.class); } catch(Exception e){ e.printStackTrace(); } return chef; } /** * Lookup the EJBs home in the JNDI tree */ private ChefHome lookupHome() throws NamingException { // Lookup the beans home using JNDI //(Properties can be used instead of Hashtable, to keep the code // compatible with jdk1.1 also.) try{ Hashtable h = new Hashtable(); h.put(Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory"); h.put(Context.PROVIDER_URL, "t3://localhost:7001"); Context ctx = new InitialContext(h); System.out.println("Initial context to look up chef home created "+ctx); Object home = ctx.lookup(CHEFHOME_JNDI_NAME); System.out.println("Lookup performed"); return (ChefHome)PortableRemoteObject.narrow(home, ChefHome.class); } catch (NamingException namingException) { System.out.println("Unable to lookup EJBHome ChefHome."); System.out.println("Check JNDI name "+CHEFHOME_JNDI_NAME+" on the WebLogic server"); throw namingException; } } //performed by the waiter after all the items are cooked, //and collected in the vector, and then served to the client. public Vector serveCookedItem(){ return cookedItems; } //called by the client, to get his check. public float getCheck(){ float checkSum = 0; Enumeration orderedItemsEnum = orderedItemsList.elements(); while(orderedItemsEnum.hasMoreElements()) { Order individualCurrOrder = (Order)orderedItemsEnum.nextElement(); checkSum += (individualCurrOrder.getItem()).getItemPrice() *individualCurrOrder.getQty(); } return checkSum; } };

Listing 15.2 ChefBean.java

/****************************************************************************** * Class Name : ChefBean.java * Description : Gets item to be cooked from the Waiter. After preparing item, * puts the prepared items onto the queue. * @author Mandar S. Chitnis, Lakshmi AM. @version 1.3 * Copyright (c) by Sams Publishing. All Rights Reserved. *******************************************************************************/ package com.sams.learnweblogic7.ejb.jms; import javax.naming.*; import javax.ejb.*; import java.util.*; import javax.rmi.PortableRemoteObject; import javax.ejb.CreateException; import javax.ejb.SessionBean; import javax.ejb.SessionContext; import javax.naming.InitialContext; import javax.naming.NamingException; public class ChefBean implements SessionBean { private String chefId; private static final boolean ENABLE_WEBLOGIC_LOGGING = true; private boolean isAvailable; private SessionContext ctx; //Defining context factory. //This is the default WebLogic's context factory. //This class can be found in the weblogic.jar package located in the //C:\bea\weblogic700\server\lib directory. public static final String WEBLOGIC_JNDI_FACTORY = "weblogic.jndi.WLInitialContextFactory"; //defining the name of the JMS connection factory which contains our queues. //this has to be configured via the admin console. public static final String JMS_FACTORY = "learnweblogic7.jms.QueueConnectionFactory"; //defining the name of the queue to be used for sending //OrderedItem Messages. public static final String ORDERED_ITEMS_QUEUE = "learnweblogic7.jms.orderedItemsQueue"; /** * Per EJB specifications to be implemented by bean, * Used when create is called on the remote interface */ public void ejbCreate(){ webLogicLog("Method ejbCreate has been called"); } // Using WebLogic's log service to log events private void webLogicLog(String logMessage) { if (ENABLE_WEBLOGIC_LOGGING) System.out.println(logMessage); } //end of webLogicLog /** * Per EJB specifications to be implemented by bean, * Presently not being used */ public void ejbActivate() { webLogicLog("Method ejbActivate has been called"); }//end of ejbActivate /** * Per EJB specifications to be implemented by bean, * Presently not being used */ public void ejbRemove() { webLogicLog("Method ejbRemove has been called"); }//end of ejbRemove /** * Per EJB specifications to be implemented by bean, * Presently not being used */ public void ejbPassivate() { webLogicLog("Method ejbPassivate has been called"); }//end of ejbPassivate /** * Sets the session context. * * @param ctx SessionContext Context for session */ public void setSessionContext(SessionContext ctx) { webLogicLog("Method setSessionContext has been called"); this.ctx = ctx; }//end of setSessionContext /** * Look up the bean's home interface using JNDI. */ private ItemHome lookupHome() throws NamingException { Hashtable h = new Hashtable(); h.put(Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory"); h.put(Context.PROVIDER_URL, "t3://localhost:7001"); Context ctx = new InitialContext(h); System.out.println("Initial context to look up BMP ItemHome created "+ctx); try { Object home = (ItemHome)ctx.lookup("BMP_ItemHome"); return (ItemHome)PortableRemoteObject.narrow(home, ItemHome.class); } catch (NamingException ne) { webLogicLog("Unable to lookup the EJBHome. Verify the ejb JNDI name BMP_ItemHome on the WebLogic server"); throw ne; } } /** * This method is called by the waiter to cook the item. * * @param orderedItem MenuItem object ordered item * @return object CookedItem */ public void cookItem(MenuItem orderedItem){ ItemHome home; ItemPK orderedItemPk; String EJBQLIngredients; String orderedItemName; String orderedItemServingSize; String orderedItemTaste; String orderedItemIngredients; String orderedItemTemperature; webLogicLog("cook Item called"); int orderedItemId = orderedItem.getItemId(); CookedItemImpl preparedItem = new CookedItemImpl(); System.out.println("The ordered item desc is:"+ orderedItem.getItemDesc()); //call the entity bean now to get the attributes for the cooked Item. try{ home = lookupHome(); orderedItemPk = new ItemPK(orderedItemId); ItemInterface orderedItemInterface = (ItemInterface)home.findByPrimaryKey(orderedItemPk); System.out.println("Item interface object created"+ System.currentTimeMillis()); orderedItemName = orderedItem.getItemDesc(); preparedItem.setItemName(orderedItemName); orderedItemServingSize = orderedItemInterface.getItemServingSize(); preparedItem.setServingSize(orderedItemServingSize); orderedItemTaste = orderedItemInterface.getItemTaste(); preparedItem.setTaste(orderedItemTaste); orderedItemIngredients = orderedItemInterface.getItemIngredients(); preparedItem.setIngredients(orderedItemIngredients); orderedItemTemperature = orderedItemInterface.getItemTemperature(); preparedItem.setTemperature(orderedItemTemperature); InitialContext ic = getInitialContext("t3://local host:7001"); SendMessagesToQueue messageSender = new SendMessagesToQueue(); messageSender.init(ic, ORDERED_ITEMS_QUEUE); SendMessagesToQueue.readAndSend(messageSender,preparedItem); messageSender.close(); // return preparedItem; } catch(Exception e){ e.printStackTrace(); } //changed here for JMS. }//end of cookItem private static InitialContext getInitialContext(String url) throws NamingException { Hashtable env = new Hashtable(); env.put(Context.INITIAL_CONTEXT_FACTORY, WEBLOGIC_JNDI_FACTORY); env.put(Context.PROVIDER_URL, url); return new InitialContext(env); } }

Listing 15.3 SendMessagesToQueue.java

/****************************************************************************** * Class Name : SendMessagesToQueue.java * Description : Sends the prepared items on the queue * @author Mandar S. Chitnis, Lakshmi AM. @version 1.3 * Copyright (c) by Sams Publishing. All Rights Reserved. *******************************************************************************/ package com.sams.learnweblogic7.ejb.jms; import java.io.*; import java.util.*; import javax.transaction.*; import javax.naming.*; import javax.jms.*; public class SendMessagesToQueue { //Defining context factory. //This is the default WebLogic's context factory. //This class can be found in the weblogic.jar package located in the // C:\bea\weblogic700\server\lib directory. public static final String WEBLOGIC_JNDI_FACTORY = "weblogic.jndi.WLInitialContextFactory"; //defining the name of the JMS connection factory which contains our queues. //this has to be configured via the admin console. public static final String JMS_FACTORY = "learnweblogic7.jms.QueueConnectionFactory"; //defining the name of the queue //to be used for sending OrderedItem Messages. public static final String ORDERED_ITEMS_QUEUE = "learnweblogic7.jms.orderedItemsQueue"; private QueueConnectionFactory qConnFactory; private QueueConnection qConn; private QueueSession qSession; private QueueSender qSender; private Queue queue; public static ObjectMessage orderedMsg; /**** Method to obtain the initial context of the queue factory ***/ private static InitialContext getInitialContext(String contextProviderUrl) throws NamingException { Hashtable envHash = new Hashtable(); envHash.put(Context.INITIAL_CONTEXT_FACTORY, WEBLOGIC_JNDI_FACTORY); //contextProviderUrl is "t3://localhost:7001" in case of weblogic envHash.put(Context.PROVIDER_URL, contextProviderUrl); return new InitialContext(envHash); } /** * Creates all the necessary objects for sending * messages to a JMS queue. * * @param ctx JNDI initial context * @param queueName name of queue * @exception NamingException if operation cannot be performed * @exception JMSException if JMS fails to initialize due to internal error */ public void init(Context ctx, String queueName) throws NamingException, JMSException { qConnFactory(QueueConnectionFactory) ctx.lookup(JMS_FACTORY); qConn = qConnFactory.createQueueConnection(); qSession = qConn.createQueueSession(false, Session.AUTO_ACKNOWLEDGE); queue = (Queue) ctx.lookup(queueName); qSender = qSession.createSender(queue); orderedMsg = qSession.createObjectMessage(); qConn.start(); } public static void readAndSend( SendMessagesToQueue itemSender, CookedItemImpl cookedItem) throws IOException, JMSException { boolean quitNow = false; do { itemSender.send(cookedItem); System.out.println("Sent Message "+cookedItem); }while(!quitNow); } /** * Send a message to a JMS queue using this method. * * @params message message to be sent *@exception JMSException if JMS fails to send message * due to internal error */ //public void send(ObjectMessage message) public void send(CookedItemImpl cookedItem) throws JMSException { /* Vector itemsVector = new Vector(); itemsVector.addElement("apple"); itemsVector.addElement("orange"); itemsVector.addElement("banana");*/ orderedMsg.setObject(cookedItem); qSender.send(orderedMsg); } /** * Closes JMS objects. * @exception JMSException if JMS fails to close objects * due to internal error */ public void close() throws JMSException { qSender.close(); qSession.close(); qConn.close(); } }

Listing 15.4 ReceiveMessagesFromQueue.java

/****************************************************************************** * Class Name : ReceiveMessagesFromQueue.java * Description : Gets the prepared items from the queue * @author Mandar S. Chitnis, Lakshmi AM. @version 1.3 * Copyright (c) by Sams Publishing. All Rights Reserved. *******************************************************************************/ package com.sams.learnweblogic7.ejb.jms; import java.io.*; import java.util.*; import javax.transaction.*; import javax.naming.*; import javax.jms.*; public class ReceiveMessagesFromQueue implements MessageListener { //Defining context factory. //This is the default WebLogic's context factory. //This class can be found in the weblogic.jar package located in the // C:\bea\weblogic700\server\lib directory. public static final String WEBLOGIC_JNDI_FACTORY = "weblogic.jndi.WLInitialContextFactory"; //defining the name of the JMS connection factory which contains our queues. //this has to be configured via the admin console. public static final String JMS_FACTORY = "learnweblogic7.jms.QueueConnectionFactory"; //defining the name of the queue to be used for sending //OrderedItem Messages. public static final String ORDERED_ITEMS_QUEUE = "learnweblogic7.jms.orderedItemsQueue"; private QueueConnectionFactory qConnFactory; private QueueConnection qConn; private QueueSession qSession; private QueueReceiver qReceiver; private Queue queue; private boolean quit = false; static Vector cookedItems = null; static int orderedItemsCtr=0; static int receivedItemsCtr=0; /** * Message listener interface. * @param msg message */ // MessageListener interface public void onMessage(Message msg) { try { CookedItemImpl cookedItem=null; if(msg instanceof ObjectMessage){ ObjectMessage objMsg = (ObjectMessage)msg; cookedItem = (CookedItemImpl)objMsg.getObject(); } else{ System.out.println("Error in message"); } System.out.println("Message Received:"); cookedItems.addElement(cookedItem); receivedItemsCtr++; } catch (JMSException jmse) { jmse.printStackTrace(); } } /** * Creates all the necessary objects for receiving * messages from a JMS queue. * * @param ctx JNDI initial context * @param queueName name of queue * @exception NamingException if operation cannot be performed * @exception JMSException if JMS fails to initialize due to internal error */ public void init(Context ctx, String queueName) throws NamingException, JMSException { qConnFactory = (QueueConnectionFactory) ctx.lookup(JMS_FACTORY); qConn = qConnFactory.createQueueConnection(); qSession = qConn.createQueueSession(false, Session.AUTO_ACKNOWLEDGE); queue = (Queue)ctx.lookup(queueName); qReceiver = qSession.createReceiver(queue); qReceiver.setMessageListener(this); qConn.start(); } /** * Closes JMS objects. * @exception JMSException if JMS fails to close objects due to internal error */ public void close() throws JMSException { qReceiver.close(); qSession.close(); qConn.close(); } /** * main() method. * * @params args WebLogic Server URL * @exception Exception if execution fails */ public static void main(String[] args) throws Exception { InitialContext ic = getInitialContext("t3://localhost:7001"); ReceiveMessagesFromQueue qr = new ReceiveMessagesFromQueue(); qr.init(ic, ORDERED_ITEMS_QUEUE); System.out.println("JMS Ready To Receive Messages (To quit, send a \"quit\" message)."); // Wait until a "quit" message has been received. synchronized(qr) { while (! qr.quit) { try { qr.wait(); } catch (InterruptedException ie) {} } } qr.close(); } private static InitialContext getInitialContext(String url) throws NamingException { Hashtable env = new Hashtable(); env.put(Context.INITIAL_CONTEXT_FACTORY, WEBLOGIC_JNDI_FACTORY); env.put(Context.PROVIDER_URL, url); return new InitialContext(env); } public static Vector getAllCookedItems(int itemsOrderedCtr){ orderedItemsCtr = itemsOrderedCtr; checkIfAllItemsCooked(); return cookedItems; } public static void checkIfAllItemsCooked(){ if(orderedItemsCtr < receivedItemsCtr){ try{ Thread.sleep(100); checkIfAllItemsCooked(); } catch(Exception e){ e.printStackTrace(); } } }

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