Advanced Queuing - Oracle

Message Navigation in Receive
}
new_order = (BolOrder)obj_message.getObject();
customer = new_order.getCustomer();
state = customer.getState();
System.out.println("Order: for customer " +
customer.getName());
}
catch (JMSException ex)
{
System.out.println("Exception: " + ex);
}
return new_order;
JMS Message Consumer Features
When a consumer does the first receive in its session, its gets the first message in the
queue or topic. Subsequent receives get the next message, and so on. The default
behavior works well for FIFO queues and topics, but not for priority ordered
queues. If a high priority message arrives for the consumer, this client program will
not receive the message until it has cleared the messages that were already there for
it.
To provide the consumer a better control in navigating the queue for its messages,
the AQ navigation modes are made available to it as JMS extensions. These modes
can be set at the TopicSubscriber, QueueReceiver or the TopicReceiver.
FIRST_MESSAGE resets the consumer’s position to the beginning of the queue.
This is a useful mode for priority ordered queues as it allows the consumer to
remove the message on the top of the queue.
NEXT_MESSAGE get the message after the established position of the consumer.
For example, a NEXT_MESSAGE issued after the position is at the fourth
message, will get the second message in the queue. This is the default behavior.
For transaction grouping
FIRST_MESSAGE resets the consumer’s position to the beginning of the queue
NEXT_MESSAGE sets the position to the next message in the same transaction.
Creating Applications Using JMS 12-69