First of all, let me admit that I am completely new to MQ, so my question might be trivial.
We are using MQs configured on Websphere and I am trying to use MQExplorer 8 to monitor the same. After connecting using the Queue Managers, I can see the Current Queue Depth, Open Input Count, etc. But I don't get any option to see the actual messages lying in a queue.
I tried googling it, but did not find anything useful.
Here is what I see:
Can some enlighten me how can I see the actual messages from a queue?
The context menu is your friend. Right-click on the queue name and select Browse.
If you are dealing with JMS messages, you can use other tools like JMSToolBox to browse and manage the messages in MQ 8 and see the JMS headers etc.
Related
We are using WebLogic 10.3.6.0 and IBM MQ 7.5.
Application design is to send messages to a dead letter queue (in WebLogic) on re-delivery. The re-delivery happens as the first delivery has failed due to some network issue or database data source failure.
My Client wants a way to browse the messages in the dead letter queue from the application GUI and pull them for processing when the network issue or data source issue has been resolved.
What is the best way to go about this?
I cam across QueueBrowser coupled with activemq or some other implementation. Is QueueBrowser possible with WebLogic? Please suggest on best ways to achieve this requirement.
Kindly pardon if my question is too naive. I am only a PL/SQL programmer.
Valerie is referring to the SYSTEM DLQ and application should never ever write to it. Application's should have there own DLQ.
i.e. If your application queue is called 'TEST.Q1' then your application DLQ should be called 'TEST.Q1.DLQ'.
There is a whole long list of MQ tools here to view messages and manage your MQ environment.
Is the application actually designed to write to the DLQ? If so, that is a very poor design. The DLQ is for the queue manager and MQ software to place messages which can not be delivered. The application should not be writing to the DLQ.
As for how to view messages on DLQ, that can be done with the MQ Explorer GUI. Or to write a script, use the DLQ handler (runmqdlq) with a rules table for processing messages.
I am working with someone who is trying to achieve a load-balancing behavior using JMS Queues with IBM Websphere MQ. As such, they have multiple Camel JMS consumers configured to read from the same Queue. Despite that this behavior is undefined according to the JMS spec (last time I looked anyway), they expect a sort of round-robin / load-balancing behavior. And, while the spec leaves this undefined, I'm led to believe that the normal behavior of Websphere MQ is to deliver the message to only one of the consumers, and that it may do some type of load-balancing. See here, for example: When multi MessageConsumer connect to same queue(Websphere MQ),how to load balance message-consumer?
But in this particular case, it appears that both consumers are receiving the same message.
Can anyone who is more of an expert with Websphere MQ shed any light on this? Is there any situation where this behavior is expected? Is there any configuration change that can alleviate this?
I'm leaning towards telling everyone here to use the native Websphere MQ clustering facility and go away from having multiple consumers pointing at the same Queue, but that will be a big change for them, so I'd love to discover a way to make this work.
Not that I'm a fan of relying on anything that's undefined, but if they're willing to rely on IBM specific behavior, I'll leave that up to them.
The only way for them to both receive the same messages are:
There are multiple copies of the message.
The apps are browsing the message without a lock, then circling back to delete it.
The apps are backing out a transaction and making the message available again.
The connection is severed before the app acknowledges the message.
Having multiple apps compete for messages in a queue is a recommended practice. If one app goes down the queue is still served. In a cluster this is crucial because the cluster will continue to direct messages to the un-served queue instance until it fills up.
If it's a Dev system, install SupportPac MA0W and tell it to trace just that one queue and you will be able to see exactly what is happening.
See the JMS spec in section 4.4. The provider must never deliver a second copy of an acknowledged message. Exception is made for session handling in 4.4.13 which I cover in #4 above. That's pretty unambiguous and part of the official spec so not an IBM-specific behavior.
I have connected to remote queue manager which has a bunch of queue's. But the Queue listeners (Open Input Count) are not showing up. The Tomcat Application server is up and running.
What could be the possible reason ?
Is there a way i can check the reason why the listeners are down ?
I think further detail is required. I would assume the qmgr is fine as you say you have connected to a remote queue manager which has a bunch of queues. check the queu
I will suggest to look on the WebSphere MQ Infocenter, you will find tons of valuable information. Nevertheless I will say that you have to check your Error logs, normally you'll check:
- The Queue manager Error Logs.
- The general WebSphere MQ Logs.
The directories depends on the platform, but Infocenter will be your friend on that!
I'm not sure what you mean when you say Queue Listeners, perhaps your intention is to refer to Queue manager Listener (for example for TCP) on certain IP port. If possible include the Completion Code and Reason code, or even the Stack Trace you get in Java.
I honestly hope this can be useful, let me know if it wasn't!
Have fun and Good luck!
What is the best approach to connect to websphere mq v7.1 and clear all the messages of one or more specified queues using Java and JMS? Do I need to use Websphere MQ specific java API? Thanks.
Like all good questions, "it depends."
The queue can be cleared with a command only if there are no open handles on the queue. In that case sending a PCF command to clear the queue is quite effective, but if there are open handles you get back an error. PCF commands are of course a Java feature and not JMS because they are proprietary to WebSphere MQ.
On the other hand, any program authorized to perform destructive gets off a queue can clear the queue. In this case, just loop over a get until you get the 2033 return code indicating the queue is empty. This can be performed using JMS or Java but both of these manage the input buffer for you. If the queue is REALLY deep then you end up moving all that data and if the app is client connected, you are moving it at network speed instead of in memory.
To get around this, you need to specify a minimal amount of buffer and as one of the GET options also specify MQGMO.TRUNCATED_MSG_ACCEPTED. This moves only the message header during the get calls and can be significantly faster.
Finally, if you are doing this programamtically and regardless of which method you use, spin off several threads and don't use syncpoint. You actually have to go out of your way to get exclusive input on a queue so once you get a session, just spawn many threads off of it. Close each thread gracefully and shut down the the session once all the threads are closed.
I'm queuing messages to a WebSphere MQ queue (NB: A point-to-point queue -- not a topic) using a stored procedure in my Oracle database. Is there a way to publish each message to multiple queues with a single call? What I would like is to find a solution that would incur zero additional latency on my database compared to sending the message to a single queue.
Solutions that involve changing my WebSphere MQ settings are certainly welcome! What I had in mind was somehow creating a "clone" queue that got all the same messages as the original one, but I've been unable to locate anything like this in the documentation.
Thanks,
Jeff
With WMQ v7 you can do this easily and with administration only. You would create a topic object and then an alias over the topic. The Oracle app writes to the alias and does not know that it is actually publishing.
Meanwhile, you make two administrative subscriptions on the topic so that publications are delivered to your two destination queues. The apps consuming them have no idea that the messages were published as opposed to delivered through point-to-point queues.
If you are not familiar with the new WMQ v7 features, take a look at the Infocenter. In particular, the "What's New in V7" section and the sections on Pub/Sub.
You can accomplish this using "Distribution Lists" in WebsphereMQ. These have to be configured on your queue manager.
Take a look at the Wesbphere MQ Application Programming Guide for more info.