I was bemoaning that I dspmqrte did not actually tell me when the message arrived on the queue (COA), and  when the application did an MQGET ( message delivered, COD).

I piped the output from the dspmqrte command into a few lines of python and got

AMQ8659I: DSPMQRTE command successfully put a message on queue SYSTEM.CLUSTER.TRANSMIT.QUEUE , queue manager QMA .
AMQ8674I: DSPMQRTE command is now waiting for information to display.
Put QM:QMA QN:CSERVER RemoteQMName:QMC
Get QM:QMA QN:SYSTEM.CLUSTER.TRANSMIT.QUEUE 
Send QM:QMA RQMN:QMC Chl:CL.QMC ChlT:ClusSdr 
Receive QM:QMC RQMN:QMA Chl:CL.QMC 
Discard QM:QMC QN:CSERVER
AMQ8652I: DSPMQRTE command has finished.

We can see the message got there because it was discarded.

I changed my back end application to ignore messages with

MsgType :MQMT_DATAGRAM  and Format :MQADMIN.

Now with the command

dspmqrte -m QMA -q CSERVER -rq CP0001 -rqm QMA -d yes -v outline -w5 -ro activity,coa,cod

I got additional messages

AMQ8654I: Trace-route message arrived on queue manager QMC .
AMQ8662I: Trace-route message delivered on queue manager QMC .

When I stopped my backend application I got the message arrived – but not the message delivered, as expected.

For a small of work in the application I got a huge improvement in problems diagnostic tools.    I was really please with my progress, and had a cup of tea to celebrate.

The title said “but…”.  This is because the message arrived, and message delivered are not displayed in real time, but are produced after the time out interval specified in the -w option had expired.  I had hoped to use dspmqrte to tell me where the delays were in route to the queue.
So all I can tell is the message got there – but not how long it took.  What a wasted opportunity to provide useful information.

So get your applications changed to ignore these trace route messages – and use the -ro COA and COD to tell you if your messages are being processed in a timely manner!

Update.
If you specify the -d yes option the message can be got by your application.
If you then mqput this message to the next application in a sequence of applications, you will get the channel activity for sending it on, and the COA and COD messages sent back when it arrives at each hop.
Unfortunately, the dspmqrte program displays the last COA, and the last COD messages.

I sent the request CSERVER on QMC.   The application sent this to queue CP0000 on QMA.  The COA and COD message displayed were for QMA.  The COA and COD messages do not tell you which queue the event applies to!

MQ has the ability to trace the activity of a message to its destination.  As chart-ware, this  statement this is 100% accurate and looks like a great facility. However, as with many bits of chart-ware the implementation is very difficult.  I can see why people tend not to use this function.

What MQ facilities are used

• With an MQMD you can set a report option MQRO_COA, confirm on arrival.  This says when the message is put to the (remote) queue, send a copy of the MQMD (optionally + payload) with msgtype of report, to the replyTo queue and replyTo queue manager .
• With an MQMD you can set a report option MQRO_COD, confirm on delivery.  This says when the message application  process the message on the (remote) queue, send a copy of the MQMD (optionally + payload) with msgtype of report, to the replyTo queue and replyTo queue manager.
• With an MQMD you can set a report option MQRO_ACTIVITY.  When the message moves through the network, the channels reports the get and send, and the receive and put of the message.   The messages produced have an embedded  PCF message within the payload.  (A message of format Embedded PCF,  MQHEPCF, allow you to have a PCF followed by other data, for example application data).
• Your application does some work and sends a reply to the replyTo queue and replyTo queue manager with msgtype of reply.  (For example “Transfer £1,000,000 to Colin Paice – has been done”)

You tie all of these pieces together with the msgid and correlid of the original message.

When a message is put on a transmission queue, it has a transmission header, with its own MQMD etc.  Your message is embedded within this transmission queue message, so your msgid and correlid are still available.

What information is available to you?

1. When your message is put to the queue, the MQMD has the time the message was put.
2. From the activity record for the sending channel, you have the time the message was got from the transmission queue, and from the embedded message you have the put time .  You can now calculate the duration spent on the transmission queue.
3. From the activity record for the sending channel, you have the time the data was sent over the network.
4. From the activity record for the receiving channel, you have the time the data was received over the network.   This should be close to the time it was sent.  If not then the clocks on the two systems may not be in sync, and you can calculate a correction factor.
5. From the activity record for the receiving channel you have the time the message was put to the queue.
6. From the Confirm on Arrival record, this should be the same (or close) to the time the receiving channel put the message to the queue.  Apply the correction factor.
7. From the Confirm on Delivery  record, you know what time the message was got by the application, and so you can calculate duration =  Time of Delivery – Time of Arrival, to see how long the message was on the server queue.    If the message is persistent, then this will include time for the channel to force the data to the log, and do disk IO.   You should be able to calculate the duration between the message being put, and the time it is processed to see the total life time of the message.

The time of day values are in the format HHMMSShh where hh is hundredths of a second.  This allows you to get granularity down to 0.01 of a second.

You now have a detailed picture of where time is being spent en route to the remote queue.  Is it the send channel being slow to the message,  or does the message gets to the remote end quickly, and the application is slow to process it.  Wow – really useful stuff.

It now starts to get messy.

These messages arrive at the specified reply to queue, and reply to queue manager.

To support using these report options, your application needs some logic like

If this is a reply message, then carry on as usual.

Else move message using  MQPUT1 to MY.ACTIVITY.PROCESSING.QUEUE, so you can process these outside of the application.

How do you process MY.ACTIVITY.PROCESSING.QUEUE ?

This is the hard bit.
You have a mixture of PCF type messages, and your original message, (perhaps with a format of MQSTR) with the MQMD saying “report message”.

MQ provides programs which can process some PCF format messages on a queue, and another program for printing (in hex) non PCF messages.  There is no program which can handle both message types and do the calculations to extract all of the useful data.

Im working on getting my Python programs to do all of this processing.

If I have made this more complex than necessary, because I have overlooked some capability, please let me know.

A big Thank You to Morag of MQGEM who pointed me to MO71.  This can format out any PCF message, and it has a trace route viewer

Select a queue manager on the main window as your source queue manager and then choose Action->Trace Message from the menu. Fill in your target queue and queue manager, and press send. You’ll get a picture like this:-

You can view the data is several ways, right click on the picture and choose Display Type.  The Display Options part of the right click context menu changes what is shown in the above picture. Another display type that might be useful is a breakdown of the steps by looking at Display Type->Nodes:-

You can set the MQMD.Report option of a message to MQRO_ACTIVITY, and get a trace of the activity sent to your reply to queue.  This is great, but not very usable.

For my MQPUT to a cluster queue I got activities

• Sending Message Channel Agent getting the message
• Sending Message Channel Agent sending it over channel CL.QMC
• Receiving Message Channel Agent receiving the data from channel CL.QMC
• Receiving Message Channel Agent putting the message to the queue on the remote system

Note, I did not get a response saying the back end application had actually processed the message.

So by setting one bit I got this extra information and can do things like calculate times and write the name of the channel used etc – great,  go out and celebrate!

The problem is that these activity trace messages come back to the reply to queue you specified in your request.  You do not want to have to process these messages in your application, as it will be an ugly program to process these PCF messages.

The best thing your application can do is put these messages somewhere else, by using  logic like

If MQMD.Format = ‘MQHEPCF’ then use MQPUT1 to put the message to “MY.ACTIVITY.TRACE.QUEUE”, and get the next message.
The activity trace replies should get to the queue before the back end applications reply, which should prevent having lost activity trace messages.

You can then use the IBM supplied  dspmqrte program, for example
dspmqrte  -i 0 -q MY.ACTIVITY.TRACE.QUEUE -m QMA -w1
to display the messages.   The Knowledge Centre is missing some documentation, for example that you specify -i 0 to get all the messages.  The KC says you have to specify the MSGID of the messages – which you will not know.

I tried to use the amqsact sample (which is meant to display activity trace messages), but it does not seem to recognize these activity trace messages as they are in MQEPCF format.

I took a copy of the amqsevt sample which processes PCF and made a few changes to support MQHEPCF format.  Im still working on how to make this available.

It is not a good idea to have this MQRO_ACTIVITY  set for all applications because of the extra overhead of the additional messages it introduces.  You could do it every 1000 messages, or if the milliseconds of the current time is .000  (so you would expect this on average once in 1000 messages).  You can then capture the data, and plot real time graphs of your MQ network, and where the delays are.
Good hunting (for delays and bottlenecks)

Yes!

The documentation says

COPYRIGHT LICENSE:

This information contains sample application programs in source language, which illustrate programming techniques on various operating platforms. You may copy, modify, and distribute these sample programs in any form without payment to IBM, for the purposes of developing, using, marketing or distributing application programs conforming to the application programming interface for the operating platform for which the sample programs are written. These examples have not been thoroughly tested under all conditions. IBM, therefore, cannot guarantee or imply reliability, serviceability, or function of these programs. The sample programs are provided “AS IS”, without warranty of any kind. IBM shall not be liable for any damages arising out of your use of the sample programs.

Each copy or any portion of these sample programs or any derivative work, must include a copyright notice as follows:

Portions of this code are derived from IBM Corp. Sample Programs.

© Copyright IBM Corp. 1993, 2019. All rights reserved.

Note – that this does not mean you can copy the code and put it up on GitHub – as GitHub is for open source, and the MQ samples are not open source.   Thanks to Matt Leming for this advice.

How difficult is to provide information which is
• clear
• provided at the right time
• accurate
• useful
From my recent experience this seems to be very difficult. Perhaps your organization is better – give it a try and see.

I went on holiday, involving two flights, and one of these was cancelled. I was amazed at how badly the airline handled this. It looked as if  this was the first time that they ever had a cancellation, and had no processes in place to handle this.   Talking to other people affected by this cancellation, the lack of clear process when there is a problem, seems very common.

We flew from Aberdeen to Manchester, and had a connecting flight from Manchester to Southampton. While we were in the air, the airline cancelled the second hop. We landed at Manchester and tried to get into the departures via the transit corridor to be told the flight was cancelled. I then got a text saying “your flight has been cancelled. Click on this link”.
The link took me to a page saying “re-book your flight”. There were no more flights that day, so it looked like we would have to stay over night at the airport.
Was the message clear ? No – it should have given us more information, told us that there was a coach being organised, where to collect your bags from, etc.
Was the message useful – no.

We went back through to arrivals and heard an announcement that people on the cancelled Southampton flight should go to the information desk.
We got to the desk and was told that a coach was provided, and our bags would be put on the coach.
We were taken to the coach, and before we got on, we checked to see if our bags were on the coach,  to be told we should have collected them first (and asked in an aggressive way,  why we had not collected them).
We had to go back to the terminal and we missed the coach. This is where the troubles really started.
We went to the airline’s service desk to be told that we had to go to the baggage handling agent’s office, next to the information desk.
• This was not accurate – there is no agent’s office.
• The information desk gave use the agents phone number. We rang it to be told that they handled missing bags, they could not help us because the plane had been cancelled, and so the bags were not lost. The bags were in the baggage transit area – and we should talk to the agent. The information the service desk told us was not useful nor correct.

When we mentioned that we had not heard any message about collecting bags, it turned out the message had been announced while we were in the air. So this message was not timely.
Eventually someone from the information desk took pity on us, went and found our bags – two hours later.

They airline had booked a hotel for us, and booked a taxi to take us there (“Out of the terminal, cross the road and use XYZ cabs”). The instructions for the taxi were totally wrong, we had to go to the taxi office close to the information office, to arrange a cab, and so it went on. I felt that the airline staff should have known this.

As the the airline frequently cancels planes, I would have expected to go to the service desk, or the information desk and to be given a piece of paper saying.

• The service desk will try to book you on a later flight. If this is unsuccessful then…
• If you were on a previous flight,  collect your bags from the following process….
•  The service desk will arrange a hotel and a taxi to take you to and from the hotel.
  •   Once you have you bags, go to the xxxx office close to the information office on the ground floor. They will organise a car for you.
• You can claim compensation, see this web site…

Maybe because I have been in a support role, I have high expectations.

How should an enterprise handle communications?

Make sure people have the right information.

When you have a major incident you need a well tested process. Once the incident has occurred, people will be dialing in to the incident hot line. You do not want to repeat the problem (One on’t cross beams gone owt askew on treddle)  twenty times – one for each new attendee. Having a blog post which people update with status is a good way of doing managing it.

You need evidence – not opinions.

It is easy to say “it must be an MQ problem because there are a lot of messages on the queue”. This usually indicates an application problem (the applications are not getting the messages fast enough), not an MQ problem. State the evidence “There are many messages on queue XYZ on queue manager ABC”. Then you can say “This can be caused by…”.   If you have no evidence, then you only have guesswork. You need to collect evidence.  I remember going out to work on a critsit on Message Broker, the problem description was “the problem is somewhere in there….”.   We turned on monitors and this showed that a SQL statement took over 10 seconds.  The table held temporary data for the duration of a transaction, and the data was never deleted.  Instead of an expected maximum of 100 rows, it had about 1 million rows.  Once we had the evidence – the root problem was obvious.

Solve the first problem first.

If there are messages accumulating on a queue at the front of the process, and also on a queue at the end of the process. They may be connected. Fix the first problem, and the second one may go away.

Be clear, and practice any actions.

With the problem with our bags, the airlines agent should have contacted the baggage handling agent, rather than us trying to talk to both ends. Decisions like switching workload, or going to a backup site need to be made by the right people. The MQ team cannot make this decision on their own.
At one site, the whole team practiced walked through problem scenarios in great detail. “We need to reconfigure the LPAR configuration; who has the userid and password for the hardware console?”. When a problem occurred, the person with this information was on a toilet and coffee break, and had left her phone on her desk. I was told that a man rushed out of the control room, burst into the ladies toilet calling out the ladies name! As a result they changed their process (you must always carry the duty phone – even in the toilets).

Make sure the messages for the end users are clear, and tell them what to do.
I had a message “you cannot do that operation at this time”. Did this mean – wait for 5 minutes because the server was down, or you cannot do the operation once you had checked in?

If you think the system will be available in 15 minutes, do not say “please retry”, but be more helpful “please try again in 30 minutes, we will update our twitter entry here… with status”.

I heard that the new CEO of a hire car company review their web site and looked at every page they expected the customer to use ( including the complaints and claiming compensation).  This resulted in major simplification of the pages, and providing much more useful information to their customers.
To test out your “error process as seen by an end user”, have a senior manager’s aged parents try out your processes and give you feedback on the chaos or smoothness of the experience!

Note.  One on’t cross beams gone owt askew on treddle is from Monty Python sketch, The Spanish Inquisition.

On Midrange MQ there a capability called trace route which allows you to see the path to a queue, and get information about the hops to the queue, for example how long was the message on the transmission queue before being sent.

If you have a problem in your MQ network. You can use dspmqrte in real time and see if there are any delays between end points.

In the blog post below, I’ll show an example of the information you can get, including where the time was spent during processing, and what you can use to automatically process the replies.

What is a trace route message?

A special (trace route) messages is sent to the specified queue (perhaps in a different queue manager), and tasks that process it en route, send information to a collection queue.

You can use the IBM supplied dspmqrte (display mq route) command. This sends the message and processes the responses.

For example; on QMA,  dspmrte put a message to a cluster queue CSERVER on QMC. During the processing of the trace route message, several messages were sent to the collection queue. Key data from the messages is displayed below.

Message 1 – processing done by dspmqrte

ApplName: dspmqrte
ActivityDesc: IBM MQ Display Route Application 

Operation: OperationType: Put
QMgrName: QMA QName: CSERVER 
ResolvedQName: SYSTEM.CLUSTER.TRANSMIT.QUEUE
RemoteQName: CSERVER 
RemoteQMgrName: QMC 

We can see from this information that the application dspmqrte Put a message to the queue CSERVER which is queue CSERVER on QMC, and it goes via SYSTEM.CLUSTER.TRANSMIT.QUEUE

Message 2 – processing done by the sending channel

ApplName: amqrmppa
ActivityDesc: Sending Message Channel Agent

Operation: OperationType: Get
QMgrName: QMA 
QName: SYSTEM.CLUSTER.TRANSMIT.QUEUE 
ResolvedQName: SYSTEM.CLUSTER.TRANSMIT.QUEUE 

Operation: OperationType: Send
QMgrName: QMA
RemoteQMgrName: QMC
ChannelName: CL.QMC
ChannelType: ClusSdr
XmitQName: SYSTEM.CLUSTER.TRANSMIT.QUEUE

We can see from this that the channel did two things (two operations) with the data

1. Operation 1: ClusSdr channel CL.QMC, did a Get from SYSTEM.CLUSTER.TRANSMIT.QUEUE.
2. Operation 2: Sent the message over the ClusSdr channel CL.QMC to queue manager QMC.

Message 3 – processing done by receiving channel

ApplName: amqrmppa
ActivityDesc: Receiving Message Channel Agent 

Operation: OperationType: Receive
QMgrName: QMC 
RemoteQMgrName: QMA 
ChannelName: CL.QMC
ChannelType: ClusRcvr

Operation: OperationType: Put
QMgrName: QMC 
QName: CSERVER
ResolvedQName: CSERVER

We can see from this that the channel did two things with the data

1. the ClusRcvr channel CL.QMC received a message from QMA,
2. The channel put the message to CSERVER on this queue manager.

End to end path

There is a sequence

1. dspmqrte put a message to queue CSERVER
   • this message was put on the SYSTEM.CLUSTER.TRANSMIT.QUEUE queue
     
2. Cluster Sender Channel CL.QMC got the message and sent it over the network
3. Cluster Receiver Channel CL.QMC received the message from the network and put it to the CSERVER queue.

There is an option to trace the return route which sometimes worked, but not consistently.

From the queue names used, and the resolved queue names, you can check the names of the queues being used. If you are using QALIAS, QREMOTE,  clustered queues, clustered QALIAS, or clustered QREMOTE you can see the true names of the objects being used, and draw a topology chart of what is actually being used (rather than what you think is being used)

Extending your applications to support trace route.

There is an option to pass the trace route message to the application processing the queue. I will write another blog post about doing this – it took me several days to get it to work. This allowed me to return data saying “colinsProg got the message from CSERVER and passed it on to NEXTHOP”. I could then build up a true picture of my application

Using the data in the messages

The returned messages have a lot of information, including OperationTime. The time is a character string with format HHMMSShh, where hh is hundredths of a second.

With my example message above

1. dspmqrte put a message to queue CSERVER at 06:10:10.00
2. Cluster Sender Channel CL.QMC got the message at 06:10:11.44 1.44 seconds later
3. Cluster Sender Channel CL.QMC sent it over the network at 06:10:11.44, no time delta
4. Cluster Receiver Channel CL.QMC received the message from the network, 06:10:11.44, no time delta
5. Cluster Receiver Channel CL.QMC put it to the CSERVER queue. 06:10:11.44, no time delta

We can see from this that there was a slight delay (1.44 seconds) before the channel got the message. The rest of the processing was very fast. If I had a problem in my MQ network, I would look at why the sending end of the channel was slow to process the message.

Problems with traceroute

I had a few problems using trace route.

The messages which flow are not true PCF messages, and so the IBM sample amqsevt (which processes PCF messages) does not recognise them. As this is sample code I was able to change it to get it to work. I’ll send the changes to IBM and hope they incorporate them in the product.  I output the messages in json and then used python to process them.

If dspmqrte thinks it has already seen a reply for the request it can throw it away and not display it.   I had this problem when instrumenting my applications to provide the trace route information.

It would be good if dspmqrte displayed the time delta from the start of the request. I had to take the output and post process it to report where the delays are.

The time OperationTime is in hundreds of a second. This may be OK for most people as if you are looking for delays in your processing, a tenth of a second may be granular enough. I added the high resolution time (epoch time) to the data provided by my applications.

If my backend application was not active there was an operation of “OperationType:Discard” and Feedback: NotDelivered. This may be because the number of handles opened for input was zero. It was a surprise. I expected to get a response saying “message expired”

My non trivial application design is to send a message to a queue CSERVER which passes a request to the backend application (on QMZ) which sends a response  back to the originator. Dspmqrte does not support this. You can set up dspmqrte to display the route between QMA and QMC. You can use a client connected dspmqrte to send a message from QMC and QMZ and then build the end to end picture yourself.

I have made some progress in instrumenting my applications to do this, but I need more time, as the documentation is unclear, wrong in places, and missing bits. I’ll send my doc comments to IBM.