IBM WebSphere MQ Interview Questions & Answers

Question 1. What Is Mq And What Does It Do?

Answer :

MQ stands for MESSAGE QUEUEING. WebSphere 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.

Question 2. What Is Message Driven Process?

Answer :

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.

Question 3. What Are Advantages Of The Mq?

Answer :

• Integration.
• Asynchrony
• Assured Delivery
• Scalability.

Question 4. How Does It Support The Integration?

Answer :

Because the MQ is independent of the Operating System you use i.e. it may be Windows, Solaris,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

Question 5. What Is Asynchrony?

Answer :

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.

Question 6. What Are The Hardware And Software Requirements For Mq Installation In Aix?

Answer :

WebSphere MQ for AIX, V5.3 runs on any machine that supports the AIX V4.3.3 PowerPC® 32.bit, or AIX® V5.1 Power 32 bit only operating system.

Disk Storage: Typical storage requirements are as follows:

• Server installation: 50 MB
• Client installation: 15 MB
• Data storage (server): 50 MB
• Data storage (client): 5 MB.

Software Requirements: Operating system: The operating systems supported by WebSphere MQ for AIX, V5.3 are:

• AIX V4.3.3, with PTF U472177, running in a 32 bit environment, on 32 or 64 bit hardware.
• AIX V5.1, with PTFs U476879, U477366, U477367 and U477368, and APAR fix IY29345 running 32 bit kernel running on 32 or 64 bit hardware.
• AIX V5.1, with PTF U476879, U477366, U477367 and U477368, and APAR fix IY29345 running 64 bit kernel running on 64 bit hardware.
• Connectivity The network protocols supported by WebSphere MQ for AIX, V5.3 are:
• TCP/IP
• SNA LU 6.2.

Databases: DB2 7.1, 7.2

Oracle 8i and 9i

Sybase v12 or v 12.5

Question 7. What Are The Software And Hardware Requirements For Installing Mq On Windows?

Answer :

MQ v 5.3 supports Windows 2000, Windows 2000XP,Windows 2000NT,

Windows 2003 SE, Windows 2003EE.

Disk Storage:

Typical storage requirements are as follows:

• Server installation: 50 MB
• Client installation: 15 MB
• Data storage (server): 50 MB
• Data storage (client): 5 MB.

Connectivity The network protocols supported by WebSphere MQ for AIX, V5.3 are: 

• TCP/IP
• SNA LU 6.2.
• LU 6.2
• NetBIOS 

Databases: DB2 7.1, 7.2

Oracle 8i and 9i

Sybase v12 or v 12.5

Question 8. What Is A Message And What Does It Contain?

Answer :

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.

WebSphere MQ messages have two parts:

• The application data. The content and structure of the application data is defined by the application programs that use it.
• A message descriptor. The message descriptor identifies the message and contains additional control information, such as the type of message and the priority assigned to the message by the sending application. WebSphere MQ defines the format of the message descriptor. For a complete description of the message descriptor,

Question 9. What Is The Max Length Of The Message Does Mq Support?

Answer :

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).

Question 10. What Is The Difference Between Persistent And Non Persistent Messages?

Answer :

In Web Sphere MQ, messages can be either persistent or non persistent. Persistent messages are logged and can be recovered in the event of a WebSphere MQ failure. Thus, persistent messages are guaranteed to be delivered once and only once. Nonpersistent messages are not logged. Web Sphere still guarantees to deliver them not more than once, but it does not promise to deliver them once.

Question 11. What Is The Effect Of Using Persistent Messages?

Answer :

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 nonpersistent message.

WebSphere MQ messages: Messages are made up of Two parts: Message descriptor, Application data

Question 12. What Is The Sizes Of Messages?

Answer :

• Qmanagerà10000 Msgs Maxmsglengthà4 Mb
• Queueà5000 Msgs Maxmsglengthà4 Mb

Question 13. What Is The Attribute Used To See The Message Length?

Answer :

MaxMsgLength

Question 14. What Is Mq Client?

Answer :

A Web Sphere MQ client is a component that allows an application running on a system to issue MQI calls to a queue manager running on another system. The output from the call is sent back to the client, which passes it back to the application.

Question 15. What Is Mq Server?

Answer :

A Web Sphere MQ server is a queue manager that provides queuing services to one or more clients. All the Web Sphere MQ objects, for example queues, exist only on the queue manager machine (the Web Sphere MQ server machine), and not on the client. A Web Sphere MQ server can also support local Web Sphere MQ Applications

Question 16. What Are The Objects Used In Web Sphere Mq?

Answer :

• Queue Manager
• Queues
• Channels
• Processes
• Name lists.

Question 17. Mention The No Of Characters Required For Creating Names Of The Mq Objects?

Answer :

• For MQ Channels it is 20 Characters
• For Remaining objects it is 48 characters.

Question 18. What About Is The Default Port Number For Mq Queue Manager?

Answer :

1414

Question 19. Difference Between Mqsc Commands And Control Commands?

Answer :

MQSC Commands: These commands are used to handle the admin related functions for the components that are present in the MQ Series. 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 the MQ Series. In general these commands are used for Channel listener, Channel Initiator, Trigger monitor etc…

Question 20. Is The Mqsc Attributes Are Case Sensitive?

Answer :

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)

• DEFINE: To define/create MQ manager objects like queue, Channels, process, and listener.
• ALTER: to update or modify the existing objects
• DISPLAY: to view all the properties of a particular object or to Display all objects
• DELETE: to delete created objects
• CLEAR: to clear the message from the queue
• END :-to come out of the queue manager
• PING :-to check whether other side channel / queue manager is ready to accept our request.
• START :- to start the particular channel or listener
• STOP :-to stop particular channel or listener
• REFRESH :-used to refresh the security every time after giving or executing, set mgr or command for queue manager or object
• RESET :-used to reset channel,cluster,queue manager
• RESOLVE :-to resolve the channel which is in indoubt state
• SUSPEND :-to suspend a queue manager from a cluster environment
• RESUME :-to remove a queue manager from a cluster environment

Question 21. How Can We Write The Mqsc Commands That Have Too Many Parameters?

Answer :

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:

• A minus sign ( ) indicates that the command is to be continued from the start of _ the following line.
• A plus sign (+) indicates that the command is to be continued from the first nonblank character on the following line.

Question 22. How Can U Make The Existing Queue Manager As An Default Queue Manager?

Answer :

On Windows systems, use the Web Sphere 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.

Question 23. Where Are The Backup Files Are Present After Creating The Queue Manager?

Answer :

Windows systems: If you use Web Sphere MQ for Windows NT and Windows 2000, configuration information is stored in the Windows Registry.

UNIX Systems:

When you install the product, the Web Sphere 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.

Question 24. What Is The Command Used For Starting The Queue Manager?

Answer :

strmqm QMName

Question 25. What Is The Command Used For Stopping The Queue Manager?

Answer :

• endmqm -w QMName : The command waits until all applications have stopped and the queue manager has ended.
• endmqm –i QMName : This type of shutdown does not wait for applications to disconnect from the queue manager.

Question 26. What’s The Message Code For Stopping A Queue Manager?

Answer :

AMQ4044 Queue manager stopping

Question 27. What Is The Command Used To Delete The Queue Manager?

Answer :

dltmqm QMName

Question 28. Display The Attributes Of The Queue Manager Qm1?

Answer :

runmqsc QM1 Display qmgr

Question 29. What Is Programmable Command Format (pcf) Commands?

Answer :

These commands are issued from a programme for local or remote administration done by programmers.

Question 30. What Is Ibm Mq Series? What Is The Significance Of Mq Series?

Answer :

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

Question 31. How To Define A Buffer Pool For Holding Messages In Main Storage? Explain?

Answer :

• 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
BUFFERS(1000)
DEFINE BUFFPOOL(buf-pool-id)
BUFFERS(integer)

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

Question 32. What Are The Telemetry Capabilities?

Answer :

• 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

Question 33. What Are The Integration And Supported Environments In Ibm Mq?

Answer :

• 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

Question 34. Mention Some Rules For Using Mqsc Commands?

Answer :

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

Question 35. What Is Queuemanager In Ibm Websphere Mq ? What Does Queuemanager Do?

Answer :

QueueManageris primary component of WebSphere MQ or WMQ. QueueManager is responsible for storing and routing messages to other Queue Manager within MQ and it also communicate with outside world e.g. Java program or any other MQ client.

Question 36. What Is Channel In Ibm Websphere Mq?

Answer :

In WebSphere MQ or WMQ, Queue Manager use channel to transmit messages to other QueueManager. Channel carries one way traffic in MQ Series (i.e. channels are uni directional). You can have either sending channel or receiving channel in MQ.

Question 37. What Is Dead Letter Queue In Ibm Mq Series?

Answer :

Dead letter Queue in WebSphere MQ is a queue which is used by QueueManager to archive messages for a non existent queue. For example of QueueManagerQMGR, receives a messages for queue ABC and if it didn’t exist on that QueueMangaer then message will be routed to dead letter queue.

Question 38. What Is Ccdt File On Websphere Mq Or Wmq?

Answer :

CCDT file or Client Channel Definition table is a binary file which contains connection details required by MQ clients e.g. Java application using JMS to connect to MQ Server. In order to connect to MQ Server, MQ clients needs MQ Server host name, MQ Server port name and server channel name. All these details are encapsulated in CCDT file named as AMQCLCHL.TAB. In order to create MQ Connection, MQ clients needs location of this file, which is provided as configuration. most of MQ errors comes either with incorrect CCDT files.

Question 39. What Is Sslpeer In Ibm Websphere Mq?

Answer :

if you connected MQ via SSL. SSLPEER is a String usually DN (Distinguished name) of MQ Client which connect to QueueManager securely using QueueManager. This is a mechanism WMQ uses to identify client. In case of Java or JMS client, SSLPEER is DN of client certificate stored in its keyStore and sent to server during SSL handshake.

Question 40. What Is Difference Between Dead Letter Queue And Backout Queue In Websphere Mq?

Answer :

 As we have seen that dead letter queue is used to store messages which is receives for non existent queue. On the other hand backout queue are application specific queue.If MQ client is not able to process message and ask for redelivery, message is redelivered to client with incremented delivery count. Once this deliveryCountcrossed a configured threshold message is moved to back-out queue for later processing or error handling. In short if MQ Series not able to deliver message to client after a preconfigured attempt, WMQ moves message to backout queue.

Question 41. What Is Difference Between Binding Connection And Client Connection?

Answer :

If MQ clients sits on same physical server where QueueManager is located than it can create binding connection which is relatively faster than client connection, which is usually created by MQ clients residing on same network but not same host. Most of application uses MQ client connection to connect QueueMangaer, which is easy and flexible.

Question 42. What Is Difference Between Local Queue And Remote Queue In Wmq?

Answer :

In WebSphere MQ, local queues are queue on same QueueManager while remote queue refers to queue on different QueueManager.