Advanced Queuing - Oracle

JMS Message Consumer Features
This mode allows the JMS client to avoid the overhead of retrieving the payload
from the database, which can be substantial for a large message.
Example Scenario and Code
In the following scenario from the BooksOnLine example, international orders
destined to Mexico and Canada are to be processed separately due to trade policies
and carrier discounts. Hence, a message is viewed in the locked mode (so no other
concurrent user removes the message) using the QueueBrowser and the customer
country (message payload) is checked. If the customer country is Mexico or Canada
the message be deleted from the queue using the remove with no data (since the
payload is already known) mode. Alternatively, the lock on the message is released
by the commit call. Note that the receive call uses the message identifier obtained
from the locked mode browse.
public void process_international_orders(QueueSession jms_session)
{
QueueBrowser browser;
Queue queue;
ObjectMessage obj_message;
BolOrder new_order;
Enumeration messages;
String customer_name;
String customer_country;
QueueReceiver qrec;
String msg_sel;
try
{
/* get a handle to the new_orders queue */
queue = ((AQjmsSession) jms_session).getQueue("OE", "OE_neworders_que");
/* create a Browser to look at RUSH orders */
browser = ((AQjmsSession)jms_session).createBrowser(queue, null, true);
for (messages = browser.getEnumeration() ; messages.hasMoreElements() ;)
{
obj_message = (ObjectMessage)messages.nextElement();
new_order = (BolOrder)obj_message.getObject();
customer_name = new_order.getCustomer().getName();
customer_country = new_order.getCustomer().getCountry();
Creating Applications Using JMS 12-73