MQ series interview questions and answers - freshers, experienced

What is IBM MQ Series? What is the significance of MQ Series?

- A middle ware from IBM.
- It has runtime managers such as Queue Managers and Queues.
- Queue is an object which holds messages of various formats: XML/text/byte.
- Queue manger maintains and manages objects like Queues, channels.
- Various listener applications listen to these queues for grabbing the messages, followed by processing these messages.
- Java Messaging Service is one of the standards provided by JEE specification for asynchronous messaging.
- The queues can be defined in JEE container and send messages on these queues.
- Message Driven Bean can be configured for listening the JMS queues.
- When a message is on the JMS queue, the corresponding MDB’s onMessage() method is invoked and the message processing can be done.

Significance of Websphere MQ Series:
- WebSphere MQ will significantly improves the flow of information across an enterprise.
- The message is placed and adjusted for dynamic business requirements.
- MQ series reduce maintenance, integration costs and acts as a bridge to various technologies.
- MQ Series reduces costs and all the disruptions are processed from data loss.
- Allows ongoing maintenance efforts through universal service delivery.
- Security breaches are eliminated and insures the compliance through message and transaction integrity.

What is a Message and what does it contain?

- A message is a string of bytes which has a meaningful usage in applications.
- Messages are utilized to transfer information across applications.
- The applications can run on the same or on different platforms.

Websphere MQ messages contain:
- Application data: The application’s content and data is defined by the application programs which uses it.
- Message Descriptor: The message is identified by the message descriptor and contains additional control information, like the type of message and priority assigned to the message.

How to define a buffer pool for holding messages in main storage? Explain.

- Buffer pool is defined by using DEFINE BUFFPOOL.
- DEFINE BUFFPOOL can be issued only from CSQINP1 data set.
- DISPLAY USAGE TYPE(PAGESET) can be used for displaying buffer pool information.
- The synonym DEF BP can also be used instead of DEFINE BUFFPOOL.
- Example:

DEFINE BUFFPOOL(buf-pool-id)
Parameter descriptions
- (buf-pool-id) Buffer pool identifier, and a mandatory entry.
- An integer which in the range from zero through 15.
- BUFFERS(integer)- Integer represents the number of 4096-byte buffers.

What are the Telemetry Capabilities?

- Telemetry enables Remote sensors, smart meters etc., to be easily connected with the existing applications and services.
- Telemetry provides messaging technique for optimizing the needs of sensor networks.
- Decision makers can focus on significant data and events.
- It enables responses of rapid and proactive nature for current situations.
- Network traffic is reduced and responsiveness increases by only sending significant data and events.
- It encourages various device manufacturers to enable their sensors that are ready to connect into IBM connectivity solutions.
- Enables the custom implementation of messaging that is device-side for connecting unusual devices.
- Optimizes the use of network to lower the traffic.
- The pay-per-byte costs can be reduced in satellite networks.

What are the Integration and supported environments in IBM MQ?

- IBM MQ supports in virtual integration.
- Supports more than 80 platform configurations, including z/OS support.
- Integrates with CICS,IMS,DB2,Microsoft .Net and JEE environments.
- Supports Message Queue Interface and Industry standards such as JMS interface along with integrated public-and-subscribe support.
- Internet secure communication is supported with industry standard SSL.
- IBM MQ supports IP V6.
- Awarded Common Criteria certification.
- Supports end-to-end governance with Extended Security Edition.

Mention some rules for using MQSC commands.

- Each command of MQSC starts with a primary parameter, followed by a secondary parameter.
- The name or generic name of the object should be followed by secondary parameter.
- The keywords, parentheses and values could be separated by unlimited number of blanks and commas.
- At least one blank immediately preceding each parameter is mandatory, except on z/OS.
- Blanks enclosed within a pair of quotations marks are significant.
- Repeated parameters are not allowed.
- String can contain blanks, lowercase alphabets or special characters other than period(.), forward slash(/), underscore(_) percent sign(%) must be enclosed in a single quote.
- A blank pair of parenthesis is invalid with out significant information enclosed in between.
- Keywords are not case sensitive.

Explain some reserved queue names of IBM Websphere MQ.

- The following are some of the reserved queue names of IBM Websphere MQ Series:
SYSTEM.ADMIN.CHANNEL.EVENT: Queue for events of channel.

SYSTEM.ADMIN.COMMAND.QUEUE: Queue for PCF command messages to be sent for non- z/OS.

SYSTEM.ADMIN.CONFIG.EVENT: Queue for events of configuration.

SYSTEM.ADMIN.PERFM.EVENT: Queue for events of performance.

SYSTEM.ADMIN.QMGR.EVENT: Queue for events of queue manager.

SYSTEM.CHANNEL.COMMAND: A distributed queuing queue on z/OS using CICS.

SYSTEM.CHANNEL.INITQ: A distributed queuing queue on z/OS without CICS.

SYSTEM.CHANNEL.SEQNO: A distributed queuing queue on z/OS using CICS.

SYSTEM.CHANNEL.SYNCQ: A distributed queuing queue on z/OS without CICS.

SYSTEM.CICS.INITIATION.QUEUE: Queue for utilization of triggering for non- z/OS.

SYSTEM.CLUSTER.COMMAND.QUEUE: Queue for communication repository changes among queue managers (applicable for AIX, HP-UX, Linux, OS/2 Warp, OS/400, Solaris, Windows, and z/OS only).

SYSTEM.CLUSTER.REPOSITORY.QUEUE: Queue for holding information about repository (applicable for AIX, HP-UX, Linux, OS/2 Warp, OS/400, Solaris, Windows, and z/OS only).

How does MQ support the Integration?

- MQ is operating system independent.
- MQ is protocol independent.
- It supports TCP/IP, LU6.2, SNA, NetBIOS,UDP.
- Sender and receiver can be from any platform.

What is Asynchrony in MQ?

- The exchanging of messages among sending and receiving programs is time independent.
- The sending and receiving application programs are decoupled.
- Sender’s process can continue with out the need of waiting for the receiver’s acknowledgement message.
- The receiver’s application need not be running while the message is sent.
- The receiver can retrieve the messages after it has been started.

What is the effect of using persistent messages?

- Persistent messages are usually logged.
- The performance of the application is reduced by logged messages.
- Persistent messages are utilized only for essential data.
- When the queue manager is stopped / failed or the data in the message is discarded, then use a non persistent message.
- As the logged data is persisted for long time and need to keep track about the events that are happening in the systems, this data need to be persisted.
- Use buffering mechanism to improve the speed of retrieving data from the logged messages.

Where are the backup files are present after creating the Queue Manager?

MS Windows Operating System:
- The configuration information of Queue Manager is stored in the Windows Registry

UNIX Operating System:
1. At the time of product installation, the Web Sphere Message Queue configuration is created. A list of queue managers are available the list is updated every time a queue manager is deleted or created. Each node has only one ‘mqs.ini’ file.

2. At the time of creating a new queue manager, a file with extension ‘qm.ini’ is created automatically. It contains configuration parameters for the queue manager.

What are the commands used for starting and stopping the Queue Manager?

To start the Queue Manager: strmqm QMName
To stop the Queue Manager: endmqm -w QMName
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