mqseries Archives - Page 4 of 7 - Mark Taylor's Blog

Warning: is it an error

Something I dealt with recently in independent exchanges with several different people was about programming with IBM MQ, and dealing with MQI errors that might not be errors. This post is a short discussion about the not-quite-failed status of a warning. Is it an error? What is the difference between MQI errors and warnings?

This post was last updated on November 15th, 2021 at 10:00 am

Controlling queue creation

A recent thread on mqseries.net asked about controlling queue creation in MQ. In particular, how to set authorities so that one user can create queues like “ABC…” but not “DEF…”. There are answers given in that thread both on the ability to do it, and the reason why it’s not usually something that’s needed.

In summary, it’s not possible to control it with setmqaut commands. And since queue creation is usually done by administrators, there’s not really any need to restrict it further.

But the thread did remind me of some code I’d written a few years ago while considering the same question as part of a larger piece of work. And so I thought I’d dredge up that PoC and make it a bit more readable. It shows how you can, in fact, implement that level of control on platforms where you can install extensions to the MQ Authorisation interface.

Variation on a theme: an MQI mistake

Theme

One of the common mistakes that people make when they first start programming with the MQI can be seen in this pseudo-code example:

MQMD md = {MQMD_DEFAULT}
MQGMO gmo = {MQGMO_DEFAULT}
int bufsize = 128
PMQCHAR buf = malloc(bufsize)
do {
  MQGET(&md,&gmo,buf,bufsize))
} while (rc != MQRC_NO_MSG_AVAILABLE)

They complain that despite pre-loading the queue, only a single message is returned. Anyone reading this is likely to recognise immediately the problem: the MsgId of the first message is returned in the md variable. The next iteration of the loop tries to match that MsgID and doesn’t find any more messages.

There are aspects of the MQI that try to minimise your chances of getting this wrong, like the MatchOptions flag in the MQGMO structure. But that in turn requires you know a) to set it and b) override the default version of the structure.

Having worked with MQ for so many years, I am hopefully not going to make that kind of mistake. But I still got caught out recently by a very similar problem.

This post was last updated on September 20th, 2021 at 08:17 am

New features with the MQ Go metric collectors

The mq-metric-samples collectors that send IBM MQ metrics and status data to a range of databases, ready to be viewed in Grafana, have just been enhanced to collect additional information. The Prometheus collector has also been extended so that it can continue providing limited status even when the queue manager is down.

The new metrics have all been suggested by users of the package either directly or via issues raised in the GitHub repository. Many previous articles on here show more about the collectors.

The InfluxDB collector is also refreshed for a new version of the database.

This post was last updated on November 27th, 2021 at 02:59 pm

What did Spring do to my queue manager

If you’ve done any work with the Spring frameworks for Java programs, then you will know that one of the good things about Spring is that it hides a lot of the underlying operations from you. But equally, one of the bad things about Spring is that it hides a lot of the underlying operations from you. I noticed that I was getting several questions about what was happening under the covers from people using the MQ Spring Boot starter. This post shows how you can see what Spring is doing to a queue manager.

This post was last updated on May 4th, 2021 at 08:50 pm

Using Loki and Grafana with MQ logs

It is odd how often similar questions come at the same time from unrelated places. Because of the projects and articles I’ve written about visualising MQ’s metrics in Grafana, I recently had a couple of people asking about using that same front-end but able to work with log-file data. Specifically would it be possible to use Loki and Grafana together with MQ. My immediate reaction was that I didn’t know what Loki was in this context, but clearly they couldn’t be asking about a Norse god or Marvel character. Instead after a very short search and a few minutes reading, I guessed that it ought to be possible to use it. Which was my reply.

But of course, I’m not likely to leave it there when I learn about a new tool. Especially when I have a reasonable starting point like a working local Grafana setup. And so I have done some very quick experiments to prove that the approach really can work. On the way I’ll also take a brief digression into using logrotate.

This post was last updated on February 9th, 2021 at 02:37 pm

Save MQ configuration as JSON

A requirement I’ve seen a couple of times recently asked how to save an MQ queue manager’s configuration in a different format than MQSC. This short post shows one way to do that.

This post was last updated on December 11th, 2020 at 10:27 am

More flexibility for user management in MQ

A new option in MQ 9.2.1 on Unix/Linux platforms gives more flexibility in user management, with no need to make operating system definitions for application users. This post describes why you might want this, how you can use the option and gives a simple example to demonstrate it. Note that this does not apply to Windows or the MQ Appliance.

This post was last updated on December 3rd, 2020 at 02:08 pm

MQ Exit source code repository

We’ve recently made available a new repository at https://github.com/ibm-messaging/mq-exits that is intended to hold the source code for various MQ Exits of different kinds.

Continue reading “MQ Exit source code repository”

This post was last updated on November 17th, 2020 at 07:47 pm

Formatting SMF records

One tool I created a few years ago deals with formatting SMF records from z/OS. I designed it to take MQ’s 115 and 116 records and generate output that users could import to spreadsheets and SQL databases. I made a video about the original version of the tool here, and I wrote about more enhancements to that tool in this post.

If you want to know more about how to use the data after formatting, then Lyn has a lot of posts at her blog site talking about analyses she has run and lessons she has learned.

Most recently I’ve added (with help) some formatting options to deal with a couple of additional record types. That work showed how non-standardised SMF records are, and how much manual work is needed to create formatters. This post will talk about how something that supposedly has a common format does not really.

This post was last updated on October 29th, 2020 at 10:19 am