The demo scripts and configuration have been produced for Docker using the IBM MQ Advanced for Developers image from the IBM Container Registry.
The bash scripts are written to work on MacOS and Linux
As well as the Docker containers the system you run this demo on will need both Docker installed and at least an IBM MQ base client and samples. For example, those found at https://developer.ibm.com/articles/mq-downloads/#c-lang for your base OS. From this you'll need both the location of the runmqsc and the pre-built samples in your path (bin and samp/bin).
This demo is based on three queue managers configured as a Uniform Cluster.
createDockerCluster.sh scripts the creation and running of three queue managers as three containers.
This script also places a CCDT (all the application connection details) for the three queue managers in a location ready for the applications in step 4
As the demo is showing how application connections are automatically balanced across queue managers you need to see where the connections go. This can be done in a number of ways but the script connections.sh is a convenient way to keep an eye on each of the queue managers. For the purposes of the demo it is best to start three separate terminals and run connections/sh QMx for each of the queue managers.
For the demo, we'll create a set of producing applications and a set of consuming applications.
A Uniform Cluster automatically maintains an even balance of multiple connections with the same application name across all queue managers in the Uniform Cluster. This requires the application to indicate that they are available to be moved, this is through use of the auto-reconnect setting used by the application. For this reason the demo uses the IBM MQ samples amqsphac and amqsghac which set this option, although you could use your own application.
It's best to have two terminals open, one for the producers and one for the consumers.
To start the producers run producers.sh, and to start the consumers run consumers.sh.
The applications connect to a virtual queue manager name *ANY_QM this is configured in the CCDT3.JSON file, for each of the queue managers. This enables approximate distribution of the initial connections, with the Uniform Cluster fine tuning that distribution once connected. Entries in the CCDT for each individual queue manager are there to support moving connections from one queue manager to another.
At this point the terminals running connections.sh should start to display the connections to each queue manager.
If there is an imbalance in the connections across the Uniform Cluster this will start to be corrected automatically within seconds.
At this point you have multiple applications connected and the Uniform Cluster constantly monitoring them. Things to try are:
As more connections are added, they will be rebalanced as needed
Stopping and starting a queue manager will show connections being moved to alternative queue managers and then connections being rebalanced once the queue manager is available again.
As the queue managers are inside containers, simply use docker stop QMx and docker start QMx.
As each of the queue managers are configured from the same set of configuration it is very easy to add more queue managers. To do that, run addQM4.sh. This does the following:
- Create the queue manager using a similar command found in
createDockerCluster.sh, only needing to change the queue manager name and the two points where the port is set in that command. - Add new entries to the CCDT by copying
CCDT4.JSONoverCCDT.JSON, this will automatically be picked up by the existing applications.