Advanced Queuing - Oracle

}
}
}
db_conn.commit();
Dequeue Features
deq_option.setDequeueMode(AQDequeueOption.DEQUEUE_LOCKED);
deq_option.setMessageId(null);
deq_option.setNavigationMode(
AQDequeueOption.NAVIGATION_NEXT_MESSAGE);
}
catch (AQException aqex)
{
new_orders = false;
System.out.println("--- No more booked orders ----");
System.out.println("Exception-1: " + aqex);
}
}
catch (Exception ex)
{
System.out.println("Exception-2: " + ex);
}
Optimization of Waiting for Arrival of Messages
AQ allows applications to block on one or more queues waiting for the arrival of
either a newly enqueued message or for a message that becomes ready. You can use
the DEQUEUE operation to wait for the arrival of a message in a queue (see
"Dequeuing a Message" on page 11-44) or the LISTEN operation to wait for the
arrival of a message in more than one queue (see "Listening to One or More
Single-Consumer Queues" on page 11-23.
When the blocking DEQUEUE call returns, it returns the message properties and the
message payload. By contrast, when the blocking LISTEN call returns, it discloses
only the name of the queue where a message has arrived. A subsequent DEQUEUE
operation is needed to dequeue the message.
Applications can optionally specify a timeout of zero or more seconds to indicate
the time that AQ must wait for the arrival of a message. The default is to wait
forever until a message arrives in the queue. This optimization is important in two
ways. It removes the burden of continually polling for messages from the
application. And it saves CPU and network resource because the application
A Sample Application Using AQ 8-75