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Retailer.javaAPI DocExample6406Wed Dec 06 18:34:58 GMT 2000chap4.b2b

Retailer

public class Retailer extends Object implements javax.jms.MessageListener

Fields Summary
private javax.jms.TopicConnection
connect
private javax.jms.TopicSession
session
private javax.jms.TopicPublisher
publisher
private javax.jms.Topic
hotDealsTopic
private javax.jms.TopicSubscriber
subscriber
Constructors Summary
public Retailer(String broker, String username, String password)


           
        try{
            TopicConnectionFactory factory = null;
            InitialContext jndi = null;

            Properties env = new Properties();
            // ... specify the JNDI properties specific to the vendor
            env.put("BROKER", broker);
            jndi = new InitialContext(env);

            factory =
                (TopicConnectionFactory)jndi.lookup("TopicConnectionFactory");

            connect = factory.createTopicConnection (username, password);
            connect.setClientID(username);

            session =
            connect.createTopicSession(false,Session.AUTO_ACKNOWLEDGE);

            hotDealsTopic = (Topic)jndi.lookup("Hot Deals");

            subscriber = session.createDurableSubscriber(hotDealsTopic,
                    "Hot Deals Subscription");
            subscriber.setMessageListener(this);
            connect.start();

        }catch (javax.jms.JMSException jmse){
            jmse.printStackTrace();
            System.exit(1);
        }catch(javax.naming.NamingException jne){
         jne.printStackTrace(); System.exit(1);
        }
Methods Summary
private voidautoBuy(javax.jms.Message message)

        int count = 1000;
        try{
            StreamMessage strmMsg = (StreamMessage)message;
            String dealDesc = strmMsg.readString();
            String itemDesc = strmMsg.readString();
            float oldPrice = strmMsg.readFloat();
            float newPrice = strmMsg.readFloat();
            System.out.println("Received Hot Buy :"+dealDesc);

            // if price reduction greater than 10 percent, buy
            if (newPrice == 0 || oldPrice / newPrice > 1.1){
                System.out.println ("\nBuying " + count + " " + itemDesc);

                TextMessage textMsg = session.createTextMessage();
                textMsg.setText(count + " " + itemDesc );

                javax.jms.Topic buytopic =
                    (javax.jms.Topic)message.getJMSReplyTo();

                publisher = session.createPublisher(buytopic);

                textMsg.setJMSCorrelationID("DurableRetailer");

                publisher.publish(
                    textMsg,
                    javax.jms.DeliveryMode.PERSISTENT,
                    javax.jms.Message.DEFAULT_PRIORITY,
                    1800000);
            }else{
                System.out.println ("\nBad Deal.  Not buying");
            }
        }catch (javax.jms.JMSException jmse){
            jmse.printStackTrace();
        }
private voidexit(java.lang.String s)

        try {
            if ( s != null &&
                s.equalsIgnoreCase("unsubscribe"))
            {
                subscriber.close();
                session.unsubscribe("Hot Deals Subscription");
            }
            connect.close();
        }catch (javax.jms.JMSException jmse){
            jmse.printStackTrace();
        }
        System.exit(0);
public static voidmain(java.lang.String[] argv)

        String broker, username, password;
        if(argv.length == 3){
            broker = argv[0];
            username = argv[1];
            password = argv[2];
        }else{
            System.out.println("Invalid arguments. Should be: ");
            System.out.println
            ("java Retailer broker username password");
            return;
        }

        Retailer retailer  = new Retailer(broker, username, password);

        try{
            System.out.println("\nRetailer application started.\n");
            // Read all standard input and send it as a message.
            java.io.BufferedReader stdin =
                new java.io.BufferedReader
                ( new java.io.InputStreamReader( System.in ) );
            while ( true ){
                String s = stdin.readLine();
                if ( s == null )retailer.exit(null);
                else if ( s.equalsIgnoreCase("unsubscribe") )
                    retailer.exit ( s );
            }
        }catch ( java.io.IOException ioe ){
            ioe.printStackTrace();
        }
public voidonMessage(javax.jms.Message aMessage)

        try{
            autoBuy(aMessage);
        }catch (java.lang.RuntimeException rte){
            rte.printStackTrace();
        }