IBM MQ Interview Questions
IBM MQ is a family of message-oriented middleware products that IBM launched in December 1993. It was originally called MQSeries and was renamed WebSphere MQ in 2002 to join the suite of WebSphere products. In April 2014, it was renamed IBM MQ. The products included in the MQ family are IBM MQ, IBM MQ Advanced, IBM MQ Appliance, IBM MQ for z/OS, and IBM MQ on IBM Cloud.
MQ stands for MESSAGING AND QUEUEING. IBM MQ allows application programs to use message queuing to participate in message-driven processing. Application programs can communicate across different platforms by using the appropriate message queuing software products.
When messages arrive on a queue, they can automatically start an application using triggering. If necessary, the applications can be stopped when the message (or messages) have been processed.
MQ is independent of the Operating System you use i.e., it may be Windows, mainframe, or AIX. It is independent of the protocol (i.e., TCP/IP, LU6.2, SNA, NetBIOS, UDP).It is not required that both the sender and receiver should be running on the same platform.
With message queuing, the exchange of messages between the sending and receiving programs is independent of time. This means that the sending and receiving application programs are decoupled; the sender can continue processing without having to wait for the receiver to acknowledge receipt of the message. The target application does not even have to be running when the message is sent. It can retrieve the message after it is has been started.
A message is a string of bytes that is meaningful to the applications that use it. Messages are used to transfer information from one application program to another (or between different parts of the same application). The applications can be running on the same platform or on different platforms.
The default maximum message length is 4 MB, although you can increase this to a maximum length of 100 MB (where 1 MB equals 1 048 576 bytes).
In IBM MQ, messages can be either persistent or non-persistent. Persistent messages are logged and can be recovered in the event of an MQ failure. Thus, persistent messages are guaranteed to be delivered once and only once. Non-persistent messages are not logged, MQ still guarantees to deliver them not more than once, but it does not promise to deliver them once.
Persistent messages are usually logged. Logging messages reduces the performance of your application, so use persistent messages for essential data only. If the data in a message can be discarded if the queue manager stops or fails, use a non-persistent message.
An MQ server is a queue manager that provides queuing services to one or more clients. All the MQ objects, for example queues, exist only on the queue manager machine (the MQ server machine), and not on the client. An MQ server can also support local MQ Applications. (This is more complicated with multi-instance queue managers etc.)
MQSC Commands: These commands are used to handle the admin related functions for the components that are present in MQ. In general MQSC commands are used for creating and maintaining Message channels, Queue Managers, Clusters etc. Control Commands: These commands are used to manage the processes and services that are helpful in the functioning of MQ. In general these commands are used for Channel listener, Channel Initiator, Trigger monitor etc.
MQSC commands, including their attributes, can be written in uppercase or lowercase. Object names in MQSC commands are folded to uppercase (that is, QUEUE and queue are not differentiated), unless the names are enclosed within single quotation marks. If quotation marks are not used, the object is processed with a name in uppercase. SCRIPT COMMANDS: After entering in to queue manager we can find script commands. Script commands are same for every queue manager. (These Commands should be used in CAPITAL LETTERS).
For commands that have too many parameters to fit on one line, use continuation characters to indicate that a command is continued on the following line:
On Windows systems, use the MQ Services snap-in to display the properties of the queue manager, and check the Make queue manager the default box. You need to stop and restart the queue manager for the change to take effect.
If you use MQ for Windows, configuration information is stored in the Windows Registry.
When you install the product, the MQ configuration file (mqs.ini) is created. It contains a list of queue managers that is updated each time you create or delete a queue manager. There is one mqs.ini file per node.
When you create a new queue manager, a new queue manager configuration file (qm.ini) is automatically created. This contains configuration parameters for the queue manager.
- What is a Queue Manager in IBM MQ?
- What is a Channel in IBM MQ?
- What is a dead letter queue in IBM MQ?
- What is the CCDT file on IBM MQ?
- What is SSLPEER in IBM MQ?
IBM MQ Interview Questions and Answers
MQ abbreviates to Messaging and Queuing. When it comes to message-driven processes, IBM enables users to simply keep up the pace with MQ with which all application programs can simply be integrated. There is no strict upper limit on the platforms when it comes to communicating and the good thing is vast support is available from IBM to enable the users to manage everything simply.
This is a slightly updated and shortened version of an article that originally appeared on careersupport.com, to read the full article, click here.
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