Hello,
I'd like to count messages in a queue using the QueueBrowser.
The queue should be examined at certain periods of time
(let's say every 3 seconds). For my testing, I sent 22 messages
to the queue. There was no receiver attached to the queue, so the
number of messages was always supposed to be 22.
I used the code below, but the output was incorrect:
Mon Aug 13 10:07:38 CEST 2001: 22 messages in queue.
Mon Aug 13 10:07:41 CEST 2001: 0 messages in queue.
Mon Aug 13 10:07:44 CEST 2001: 0 messages in queue.
Mon Aug 13 10:07:47 CEST 2001: 0 messages in queue.
Mon Aug 13 10:07:50 CEST 2001: 0 messages in queue.
...
----------------
try {
queueConnection = queueConnectionFactory.createQueueConnection();
queueSession = queueConnection.createQueueSession(false,
Session.AUTO_ACKNOWLEDGE);
queueBrowser = queueSession.createBrowser(queue);
while (true) {
long count = 0;
/* queueBrowser = queueSession.createBrowser(queue); */
Enumeration messageList = queueBrowser.getEnumeration();
while (messageList.hasMoreElements()) {
++count;
messageList.nextElement();
}
Date now = new Date(System.currentTimeMillis());
System.out.println(now.toString() + ": "
+ String.valueOf(count) + " messages in queue.");
/* queueBrowser.close(); */
Thread.sleep(3000);
}
} catch (Exception e) {
System.out.println("Exception occurred: " + e.toString());
} finally {
// release resources
}
----------------
Then I tried to use different approach. I changed the loop, so that
I create a new QueueBrowser object, get the Enumeration of messages
currently in the queue, count the messages, and close the QueueBrowser.
The modified lines are enclosed in comments.
The changed code works as expected:
Mon Aug 13 10:34:12 CEST 2001: 22 messages in queue.
Mon Aug 13 10:34:15 CEST 2001: 22 messages in queue.
Mon Aug 13 10:34:18 CEST 2001: 22 messages in queue.
Mon Aug 13 10:34:21 CEST 2001: 22 messages in queue.
Mon Aug 13 10:34:24 CEST 2001: 22 messages in queue.
------------
Does it mean that the QueueBrowser is kind of a "disposable" object?
I would expect that it is be possible to re-use a single QueueBrowser
to enumerate messages several times.
Is this intended behaviour or a bug?
Thank you in advance
Michal Palicka, Cleverlance
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