ex8_16.txt

j2ee core design patterns

Example 8.16 	Order Sender Application Service: OrderSenderAppService.java
// imports...

public class OrderSenderAppService {
	// Queue session and sender: see JMS API for details
	private QueueSession orderQueueSession;
	private QueueSender orderQueueSender;

	// These values could come from some property files
	private String connectionFactoryName =
			"PendingOrdersQueueFactory";
	private String queueName = "PendingOrders";

	// use a service locator to locate administered
	// JMS components such as a Queue or a Queue.
	// Connection factory
	private JMSServiceLocator serviceLocator;
	. . .
	// method to initialize and create queue sender
	private void createSender() {
		try {
			// using ServiceLocator and getting Queue
			// Connection Factory is similar to the
			// Service Activator code.
			serviceLocator = ServiceLocator.getInstance();
			queueConnectionFactory =
					serviceLocator.getQueueConnectionFactory(
					connectionFactoryName);
			queueConnection =
					queueConnectionFactory.createQueueConnection();

			// See JMS API for method usage and arguments
			orderQueueSession =
					queueConnection.createQueueSession(. . .);
			Queue ordersQueue =
					serviceLocator.getQueue(queueName);
			orderQueueSender =
					orderQueueSession.createSender(ordersQueue);
		}
		catch(Exception excp) {
			// Handle exception - Failure to create sender
		}
	}


	// method to dispatch order to fulfillment service
    // for asynchronous processing
	public void sendOrder(Order order) {
		try {
			// create a new Message to send Order object
			ObjectMessage orderObjectMessage =
					queueSession.createObjectMessage(order);

			// set object message properties and delivery 
			// mode as required.
			// See JMS API for ObjectMessage

			// Set the Order into the object message
			orderObjectMessage.setObject(order);

			// send the message to the Queue
			orderQueueSender.send(orderObjectMessage);
    
			. . .
		} catch (Exception e) {
			// Handle exceptions
		}
		. . .
	}

	. . .

	public void close() {
		try {
			// cleanup before closing
			orderQueueReceiver.setMessageListener(null);   
			orderQueueSession.close();     
		}
		catch(Exception excp) {
			// Handle exception - Failure to close
		}
	}
}