CODEWITHSUNDEEP
javaibm-mq
Porter
Porter

Reputation: 143

Delete top message from MQQueue

I am constructing a messaging system using MQSeries. For some reason, when I perform q.get(...), I am getting an exception thrown (I don't know the specific MQException). Below is the code causing the error:

private static MQGetMessageOptions GMO = new MQGetMessageOptions();
private static int GMO_OPTIONS = MQC.MQGMO_SYNCPOINT | MQC.MQGMO_WAIT;
GMO.options = GMO.options | GMO_OPTIONS;
GMO.waitInterval = MQC.MQWI_UNLIMITED;

MQEnvironment.hostname = args[0];
MQEnvironment.channel = args[2];
MQEnvironment.port = Integer.parseInt(args[1]);
MQQueueManager queueManager = new MQQueueManager(args[3])

MQMessage msg = new MQMessage();
MQQueue q = queueManager.accessQueue("qName1",MQC.MQOO_OUTPUT);
q.get(msg, GMO);

My plan is, when this error occurs, skip the message and delete it. To perform the delete I will call the following function:

private void deleteMsg(MQQueueManager queueManager, String queueName) throws MQException {
    MQGetMessageOptions tempGmo = new MQGetMessageOptions();
        tempGmo.options |= MQC.MQGMO_WAIT;
        tempGmo.waitInterval = 1000;
    MQQueue remover = queueManager.accessQueue(queueName, MQC.MQOO_INPUT_AS_Q_DEF);
        remover.get(new MQMessage(), tempGmo);
        queueManager.commit();
}

Would the remover.get() in my deleteMsg function also, in this specific scenario, fail for the same reason? Or does the option used to construct the MQQueue(MQC.MQOO_INPUT_AS_Q_DEF vs MQC.MQOO_OUTPUT) prevent it from also failing? If I am having trouble accessing my queue's message, how do I discard the top message and move to the next?

To shorten my question: If I am unable to perform a get() on a given queue to retrieve a message, how can we delete that corrupt message on the same queue?

Thank you!

Upvotes: 4

Views: 1346

Answers (3)

Shashi
Shashi

Reputation: 15283

I wonder if the program compiled because there is no option called GMO_OPTIONS. All MQ constants are prefixed MQC

Upvotes: 0

Roger
Roger

Reputation: 7506

OMG!

MQQueue q = queueManager.accessQueue("qName1",MQC.MQOO_OUTPUT);
q.get(msg, GMO);

Your are opening a queue for output (writing) but you are trying to get a message. You have your shoes on the wrong feet!! Secondly, why aren't you catching the MQException that MQ would be throwing?? The exception would have included the reason code which would have given you the exact explanation to your issue.

Here's how you should be opening the queue for reading:

try
{
   int oo = MQC.MQOO_INPUT_SHARED + MQC.MQOO_FAIL_IF_QUIESCING;
   MQQueue q = queueManager.accessQueue("qName1",oo);
   MQGetMessageOptions gmo = new MQGetMessageOptions();
   gmo.options = MQC.MQGMO_NO_WAIT + MQC.MQGMO_FAIL_IF_QUIESCING;
   q.get(msg, gmo);
}
catch (MQException e)
{
   System.err.println(e.getLocalizedMessage() );
   System.err.println("CC = " + e.completionCode + " - RC = " + e.reasonCode);
}

Also, make sure you use the appropriate "Fail if quiescing" option for the particular MQ API call.

Finally, look up "backout queue". If your application is having an issue with a message then the message should be moved to a backout queue and not simply deleted.

Upvotes: 4

AlexR
AlexR

Reputation: 115388

I do not why what you are doing does not work for you but I wonder why are you using proprietary API of MQ Series instead of using JMS API. In JMS terms remove top message just means receive the message, so call of session.receieve() does the work.

Using common JMS API has a lot of advantages. The main of them is that you can easily move from MQ Series to any other messaging solution without changing even one line of your code.

Upvotes: 0

Related Questions