MQ and Node.js: working with TypeScript

MQ application programs for the Node.js environment can now use TypeScript definitions. This brings the opportunity to compile and check your JavaScript programs for correctness before running them. This post will talk more about what TypeScript is and how it can help your MQ Node.js development activity.

Substantial credit for the API definitions and translations of the example programs needs to be given to Andre, who submitted a Pull Request to our github repository.

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This post was last updated on January 22nd, 2022 at 06:00 pm

Resolving subscription authorisation failures

It never fails to amaze me how often the same question gets asked by different people from different projects at around the same time. This time, I was asked by two people about resolving subscription authorisation failures. I could find lots of information about IBM MQ publish/subscribe, and general descriptions of what security checks are made. But there was not so much on how to use information from the queue manager that can help to deal with the inevitable failures.

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This post was last updated on December 13th, 2021 at 01:23 pm

Decoding MQI constants

On Twitter, Michael asked: “any logic or hints on how to interpret the PCF parameter names returned as multiples from the com.ibm.mq.headers.pcf?” Which is a very good question but a proper answer is far too long to type there. There are several different ways that you can approach the problem, depending on what you are trying to do. So this post talks about decoding MQI constants.

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This post was last updated on December 15th, 2021 at 11:57 am

Event formatter changes with MQ 9.2.4

IBM has just announced MQ 9.2.4. No matter how hard you search the announcement letters you will still not be able to find anything about the event formatter changes that I was able to slip into the release. That’s because changes to samples don’t normally deserve highlighting in formal marketing documents. But I hope this change still turns out to be useful.

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This post was last updated on November 24th, 2021 at 01:12 pm

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?

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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.

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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.

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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.

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

New interface for MQ Requirements

The Request for Enhancement (RFE) system that lets you submit new requirements and ideas for IBM MQ has been moved to a new interface. Just about all IBM products are moving to use Aha! to give a common front-end, and it is now MQ’s turn to migrate.

This post is a quick look at what this means.

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This post was last updated on September 7th, 2021 at 02:33 pm

How many screens is too many?

Doing a web seminar session yesterday I knew I wanted a second machine available. Partly as an HA failover backup (just in case), and partly to act as a view of what the other participants were seeing – which I can’t see on the system I’m driving a presentation from. Though as I cabled everything together, it did start to look a little silly. Or like a set from a bad TV show.

Five screens
Five screens, one desk

But I did actually find a use for just about all of the panels.

The secondary system had the live seminar contents, along with the text-based chat screen so I could see when people raised questions. And I had some written notes associated with the presentations that I could scroll through as the event progressed.

The primary system had one panel with the full-screen presentation, another panel with a preview of the next slide, and a further panel with all my other activities including a chat window where I could type private notes to my co-presenter if necessary.

Could I have managed with fewer screens? Probably, but having all that space did make it easy to manage and have the windows and fonts expanded large enough so I didn’t have to peer hard at small text.

I’ve now moved the 2nd laptop next to the big TV so I can use it to show the county championship cricket games available only via live streaming services. But it can brought back to the desk if needed for another web conference.

This post was last updated on April 30th, 2021 at 02:41 pm