my question is about WebSphere MQ's Dead-letter.
How I can view on ISPF the queue manager's dead-letter?
Each queue manager has a default dead-letter queue or I need to define it?
Thanks so much!
A queue manager does not have a dead-letter queue by default. You must tell the queue manager where its dead-letter queue is. The CSQINP2 samples (if you use them) define a QLOCAL called ++qmgr++.DEAD.QUEUE - see sample CSQ4INYG. If you use that sample and do the search and replace on the ++qmgr++ text, you may have the queue defined. But, you still need to tell the queue manager to use that queue as its dead-letter queue.
To view whether a queue manager has a dead-letter queue, you need to issue the following command:-
DISPLAY QMGR DEADQ
Alternatively you can view the same information on the MQ ISPF panels by
Chosing option 1. List or Display
For Object type MANAGER
Hit enter, and view the first page of queue manager details. Just below 'Description' and 'Default transmission queue' you will see 'Dead-letter queue'
To alter it, use option 3. from the ISPF panels or issue the following command:-
ALTER QMGR DEADQ(CSQ1.DEAD.QUEUE)
Changing the above queue name to be correct for your queue manager.
You can use any named queue you wish, you do not have to follow the convention used in the CSQ4INYG sample, but I would recommend having a name that indicates the purpose of the queue clearly.
Related
I have a Normal IBM MQ developer edition 924 installed on a ubuntu virtual machine. And have cpp code files for Publisher and Subscriber model. I created a topic and started sending messages on the topic.
The issue happens when I send a larger message on the topic, the error code of 2031(MQRC_MSG_TOO_BIG_FOR_Q_MGR) is outputted. (https://www.ibm.com/docs/en/ibm-mq/9.1?topic=arc-2031-07ef-rc2031-mqrc-msg-too-big-q-mgr)
I changed the maxmsgl value for the Queue manager and the SVR channel as well. I ran the following commands for this:
runmqsc QM1
ALTER QMGR MAXMSGL(104857600)
ALTER CHANNEL(SYSTEM.AUTO.SVRCONN) CHLTYPE(SVRCONN) maxmsgl(104857600)
But still the error persists, could someone reflect on what needs to be done regarding this error code. And also as message segmentation is not allowed on pubsub what is the maximum limit of message size it can handle.
When using a topic for publish/subscribe, the messages sent to subscribers are still put onto a queue for safe storage until they are consumed by the subscribing/getting application. These queues must also have MAXMSGL set appropriately.
If you do not know which queue to adjust, follow these steps:-
Run the subscriber application - assuming that it will wait around for a while
Issue the following MQSC command (e.g. using runmqsc):-
DISPLAY SUB(*) DEST DESTCLAS TOPICSTR DURABLE
The name shown in the DEST field in the output is the queue your subscription is using. If it's name starts with SYSTEM.MANAGED and it also shows DESTCLAS(MANAGED) then your subscription is a managed subscription. You say that your subscription is not managed, but if you don't know which queue is in use by that subscriber then it is most likely that it IS managed, since that means you don't have to worry about the queue.
A managed subscription queue is built from a MODEL queue referenced on the topic. If you are unsure which MODEL queue would be used, issue the following command using the TOPICSTR value from the output of the above command.
DISPLAY TPSTATUS('topic-str-value') MNDURMDL MDURMDL
If the output from the DISPLAY SUB command earlier showed that your subscription was DURABLE(YES) then the MODEL queue in use is the one shown in the field MDURMDL (Managed DURable MoDeL). If it showed DURABLE(NO) then the MODEL queue in use is the one shown in the field MNDURMDL (Managed Non-DURable MoDeL).
Using the name determined in step 4 if it is not managed, or in step 5 if it is managed, issue the following MQSC command:-
ALTER QLOCAL('q-name-from-step-4') MAXMSGL(104857600)
or
ALTER QMODEL('q-name-from-step-5') MAXMSGL(104857600)
Now re-make your subscription (so that it deletes the previous temporary queue it created and makes a new one from the model) and re-run your publisher application.
I have two MQ queue manager with same queue names configured. Both are configured to send data to different servers. Currently queue manager(QM1) is stopped(status Ended Immediately) and QM2 is running
Now my program opens the queue and sends data. It doesnot specify queue manager name. When I execute the program, MQ connection request returns error 2059.
My questions are:
What happens when multiple queue managers have same queue name?
How to tackle situation without changing the code?
Please forgive if the description is vague. It would be helpful if anyone provide links so that newbie like me can learn something.
Thanks
It would be helpful if could provide details on your application. Whether it's using server bindings or client mode connection to queue manager. What version of MQ are you using?
The below information is valid for MQ v7.x:
If you are using client mode then you can use multiple CONNNAMEs to connect. If one queue manager is down, your application will connect to next queue manager in CONNAME list. One of the simplest way to do when using client mode connection is to define MQSERVER environment variable and specify multiple CONNNAMEs.
SET MQSERVER=<channel name>/TCP/host1(port1), host2(port2)
For example when both queue managers are on local host:
SET MQSERVER=MYSVRCONCHN/TCP/localhost(1414),localhost(1415)
In server bindings mode if queue manager name is not specified, then application will attempt to connect to the default queue manager. If the default queue manager is down, then 2059 is thrown.
Your explaination doesn't provide clarity about your requirements.
You wrote:
My questions are 1. What happens when multiple queue managers have same queue name.
Nothing. Its a normal scenario. Different queue managers may have queues with same name and it doesn't create any ambiguity. Although, scenario will be a little different when the queue managers are in same cluster and the queue is also a cluster queue. Then everything will depend on requirements and design.
You wrote:
2. How to tackle situation without changing the code
Run the queue manager which is stopped.
You wrote:
Now my program opens the queue and sends data. It doesnot specify
queue manager name.
What application are you using?For a client application, you access a queue using an object of queue manager.
I am asssuming that you are using an application(client) which doesn't take queue manager details from you, only takes queue details. And may be the queue manager is hard coded within the code. And it sends the message first to the queue of Queue manager 1 and then to queue manager 2. But, in your case queue manager 1 is down.
If above is the case, then the application's code needs to be changed. You should have exception handling in such a way that it executes the code for sending the message to the second queue manager even though the first lines of code throws error.
We have set up BOTHRESH(5), BOQNAME(USER.ERR) in WebSphere MQ v7.0.1.9 queue manager.
When TX is rolled back by the MDB in a container managed TX in WebSphere application server v7, the messages are getting placed in DLQ instead of placing in original queue.
I checked the logs which stated that TX got rolled back successfully .
Can some one help me?
...the message are getting placed in DLQ instead of placing in original queue.
Setting BOQNAME and BOTHRESH results in the QMgr attempting to put the message in something other than the original queue. Once BOTHRESH is exceeded, the QMgr will first try to put the message into the queue named by BOQNAME, then into the DLQ if putting to BOQNAME is not possible. Only if both of these fail does the QMgr put the message back on the original queue or discard it if the message is non-persistent.
Some reasons that backing out to the queue named in BOQNAME or to the DLQ fail are:
The target queue does not exist.
The target queue is full.
The message size exceeds the target queue's MAXMSGL attribute.
The user is not authorized to put messages onto the target queue.
The target queue is of the wrong type (i.e. XMitQ or model queue).
When putting to the DLQ, the QMgr's DEADQ attribute is empty.
BOTHRESH is set but BOQNAME is not. In this case, the DLQ is the only queue tried.
I was wondering if there is a way for you to configure a queue to automatically clear messages? We are striving to partially implement a component of our architecture and want to be able to send to the queue, but have the queue automatically remove the messages that are being sent so that we don't have to run scripts, etc to perform the clean-up.
So far the only thing I have been able to find is to run CLEAR QLOCAL or set the messages to expire from the publishing application.
For you use case there are a few options in IBM MQ:
Create a QALIAS that points to a TOPIC object which has a topic string with no subscribers, messages put to the QA will just disappear.
Have the sending application set message expiry.
Use the IBM MQ CAPEXPRY feature to administratively force message expiry at the queue level.
Run a script to issue CLEAR QLOCAL against the queue. There can not be open handles on the queue for this to work.
Programmatically issue the equivalent PCF command to CLEAR QLOCAL against the queue. There cannot be open handles on the queue for this to work.
Run the IBM MQ dmpmqmsg utility against the queue to read and discard the messages.
I used the Subscriber SYSTEM.JMS.D.SUBSCRIBER.QUEUE and Client ID as setClientID("USER1") and used topicSubscriber = topicSession.createDurableSubscriber(topic,"SUB1");
The topicSubscriber is created and while trying to receive using this topicSubscriber.receive(); , it is not receiving the messages from topic , but there are messages in topic.
Can any one say why its not receiving messages and whether i need to chek any queue configurations.
Any help is appreciated.
Thanks in advance.
I already had topicConnection.Start() in my coding , also i checked in TopicSession there is no Start() Method.
The same code with Non durable subscriber method topicSession.createSubscriber(topic); is working , but for durable it is not working.
Thanks
Sorry, yes I meant topicConnection.Start(). It was worth a check.
I got the answer for durable subscriber not working ,
My queue depth has reached the max queue depth , so the subscriber is not able to subscribe the message.
Eg . my max queue depth for queue SYSTEM.JMS.D.SUBSCRIBER.QUEUE is set to 100 , and if we check our current queue depth and if it reaches 100 the subscriber will not work.
As an alternative way iam trying to create with Temporary Topic , here iam getting an error while creating the durable subscriber topicSession.createDurableSubscriber(topic,"SUB1");
JMS Exception :: javax.jms.InvalidDestinationException: MQJMS0003:
Destination not understood or no longer valid
Can anyone help to solve this error.
Thanks in Advance.
The problem seems to be how you are using SYSTEM.JMS.D.SUBSCRIBER.QUEUE. You appear to be directing messages and subscribers to this queue as the destination for a durable subscription. IBM MQ uses that queue to manage durable subscriptions.
As a general rule, queues whose names begin with SYSTEM are for internal system use by MQ. Some of them, such as SYSTEM.ADMIN.*.EVENT are OK to get messages from but you would not use these as a subscription destination for unrelated messages either.
Many tutorials use SYSTEM.DEFAULT.LOCAL.QUEUE as a destination for messages but this is only because the queue is known to exist on all versions of MQ and MQ uses only the definition of the queue and never the content of that queue. It is easier for the tutorial writer (and IBM is just as guilty here) to point at SYSTEM.DEFAULT.LOCAL.QUEUE then to walk the student through the need for and means to create their own queue. So although best practices suggest it should not be an exception to the "do not use SYSTEM objects" rule, common usage makes SYSTEM.DEFAULT.LOCAL.QUEUE the de facto exception.
The other exceptions are, of course, the command queues for MQ, MFT and IIB. These are also names SYSTEM.* but are designed for users to communicate with the software listening on the queue.
Note that all the exceptions "do not use SYSTEM objects" rule are interfaces between applications and MQ system resources. The event queues are MQ sending information to the user. The command queues are the user sending information to the system components. A subscription is neither of these categories. A destination for a subscription is considered an application-owned object, even when the system manages it on behalf of the subscriber.
When you want a durable subscription, either let the system assign a permanent queue and use that, or else pre-define a queue (that is not named SYSTEM.*) and use that. Whatever else you do, please do NOT try to hijack MQ's internal system queues for application-level purposes.