MQSeries Interview Preparation Guide

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A message is a string of bytes that has meaning to the
applications that use it
Message = Header(s) + Application Data
A message consists of a header and the attached application
data.
Headers like:
Unique Message Id, Routing information, Message format

The data part of a message:
A record from an indexed or flat file
A row from a DB2 table
Individual columns from DB2 tables
Multiple rows or records

1.Local queue -is a real queue
2.Cluster queue -is a local queue that is known throughout
a cluster of queue managers
3.Remote queue -structure describing a queue
4.Transmission queue(xmit quueue) -local queue with special
purpose
5.Initiation queue -local queue with special purpose
6.Dynamic queue -local queue created "on the fly"
7.Alias queue -if you dont like the name
8.Dead-letter queue -one for each queue manager
9.Reply-to-queue -specified in request message
10.Model queue -model for local queues
11.Repository queue -holds cluster information

When you are using Internet Explorer (IE) attached
documents created in Microsoft Office (Word, Excel,
PowerPoint) will open up in the content frame. Attached
Office documents in Netscape will ask you if you want to
"download the document to your hard drive" or "open it in
its current location." The former will not open the document
but save it to your computer. The latter will launch the
program in which the document was created.

With IE, pressing the Enter key will activate such buttons
as "Submit" and "Log-in". In Netscape you must actually
click on these buttons.


Note: Netscape does not always work properly. Sometimes
items an instructor adds will not appear where they should,
links may not function properly, etc. This is why it is
strongly encouraged that everyone use Internet Explorer 5.5
or above for all functions of Blackboard. In any case DO NOT
use the AOL browser. Certain functions such as assessments
do not work properly.

Using CICS Transaction Gateway we can connect MQ Serires
with Power Builder 8.0

Yes, we can handle the message in deadletterq?
how means.
ans> we have two commands to retrieve messages from DLQ.
Action(fwd) fwdq fwdqm.
then that DLQ message forward to this particular q.
ACTION(RETRY)

Channel means logical communication link. There are two
types of channels
1) message channel,
2) MQI channel


1) Mesage channel use for communication between QMgr to
QMgr.

2) MQI channel use for for communication between QMgr to
MQ client

DLQ - Dead Letter Queue

If an application tries to put a message to another
application and if it is not delivered then it goes to the
DLQ. So DLQ is nothing but all undelivered messages stored
in DLQ.

Alterenate Defination:
The dead-letter queue is a local queue where messages are
put if they cannot be routed to their intended destination

You need to create a DLQ at the time of creating a Queue
Manager.

crtmqm -q -d MY.DEFAULT.XMIT.QUEUE -u
SYSTEM.DEAD.LETTER.QUEUE SATURN.QUEUE.MANAGER

where -u is dead letter queue

Cluster is said to be group of queue manager's logically
connected together to balance the load on the remote machine
(i.e if it is remote queue managers which processes your
message). And there are two types of grouping on the queue
managers.
1) Full repository
2) Partial repository.

The full repository queue manager knows all other queue
managers in the cluster and whenever a message comes to it,
and if that is unable to process the message, it will find
a queue in other queue manager in the cluster and ask it to
process the message.

Queue is a data structure which is store the messages.and
every queue has own queue manager.queue manager are
maintaining the all queues.different types of queues are
available in web sphere mq in different purpose.but
generally 4 types of queues r there
1)local queue
2)remote queue
3)alias queue
4)model queue

it speeds implementation of distributed applications.
it runs on different platforms
it time independent.
no loss for msg delivery ie gaurenty delivery.

SDSF (spool Display Search Fecility)

event queues
Open MQ Explorer by selecting Start > Programs > IBM WebSphere MQ > WebSphere MQ Explorer.
Check to see if the depth of the WebSphere® Sensor Events queues is greater than zero.

one is pub/sub concept

we have 2 types of Logfiles in MQ.
1. Error logs.
these logs can be found under
/var/mqm/qmgrs/<QMGRNAME>/errors and the log files starts
with AMQERR01.LOG/AMQERR02.LOG/AMQERR03.LOG. These logs are
used to capture error logs to that particular logs.
/var/mqm/errors. Unthis DIR again you see same files. This
will capture errror logs related to all QMGRS in the server.
2. Transacational(ACTIVE) logs.

These logs are used for media recovery and restat recovery.
Location:/var/mqm/log/QMGR/active. File names starts with S.
Space to these files are allocated based on your settings in
qm.ini file.
This we call as logspace.

#runmqsc <QMGR NAME>

dis chs(channel name) ALL

you will see an attribute called MSGS and that tells you how
many messages passed through that particular channel instance.

IBM MQ is a family of network software products that IBM launched in March 1992. 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.

Message:
Messages are collections of binary or character (for instance ASCII or EBCDIC) data that have some meaning to a participating program. As in other communications protocols, storage, routing, and delivery information is added to the message before transmission and stripped from the message prior to delivery to the receiving application.
Queue:
Message queues are objects that store messages in an application.

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 Queue Manager QMGR, receives a messages for queue ABC and if it didn't exist on that Queue Manager then message will be routed to dead letter queue.

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.

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.

Another interesting and frequently asked WebSphere MQ Interview Question. You can easily answer this MQ question 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.

Rather simple and fact based MQ Series interview question. This is asked to see whether candidate is familiar with MQ Series terminology or not. In WebSphere MQ, local queues are queue on same QueueManager while remote queue refers to queue on different QueueManager.

This MQ interview question is more to know that which version of MQ have you worked upon, do you familiar with any issue with that particular version or many major changes to previous or next version etc. Based upon your answer, you may expect some follow-up questions. By the way current version of WMQ is WebSphere MQ 7.5 but it always good to check IBM's MQ website for latest version.

I like this MQ Interview question to ask because many times having experience of one or more Messaging technology or Messaging Middle-ware is good. As I said earlier Tibco RV, Tibco EMS and MQ Series are some of the popular messaging technology used in Java applications. On MQ front there are couple of more MQ providers e.g. Sonic MQ and Active MQ. Active MQ is free and from Apache software foundation, which is easy to install and use. You can use Active MQ for your development and test environment. it also provide a useful Queue browser to keep track of Queues and number of message on it.

☆ The message can be retrieved in First-in-first-out (FIFO) basis.
☆ Message priority - defined in the message descriptor. Messages with same priority are retrieved on a FIFO basis
☆ A specific message can be retrieved by a program request.