What is MQ and what does it do?
MQ stands for MESSAGE QUEUEING. Web Sphere 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.
What is Message driven process?
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.
What are advantages of the MQ?
1.Integration.
2. Asynchrony
3. Assured Delivery
4. Scalability
How does it support the Integration?
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
What is Asynchrony?
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.
What is a Message and what does it contain?
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.2. 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.
What is the Max Length of the message does MQ support?
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).
What is the difference between Persistent and Non Persistent Messages?
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.
What is the effect of using Persistant messages?
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.
What are WebSphere MQ messages types?
Messages are made up of Two parts: Message descriptor, Application data
Types of messages?
Datagram: A Message sent with no response expected.
Request: A Message sent for which a response is expected.
Reply: A Response Message for a requested message.
Report: A Message that describes the occurrence or event
What is the attribute used to see the Message length?
MaxMsgLength
What is MQ Client?
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.
What is MQ Server?
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
What are the Objects used in Web sphere MQ?
1.Queue Manager 2. Queues
3. Channels 4. Processes
Name listsWhat is Channel in IBM WebSphere MQ ?
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.
What is Initiation Queues?
Initiation queues are used for triggering
A trigger message is put by a queue manager on an initiation queue when a trigger is occurred
Logical combinations are part of a trigger event which is detected by the queue manager
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
What is dead letter queue in IBM MQ Series ?
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 QueueManager QMGR, receives a messages for queue ABC and if it didn’t exist on that QueueMangaer then message will be routed to dead letter queue.
What are the message sizes?
For Queue manager, the limit is 4 MB
For a Queue the limit is 4 MB
The default memory size for Q Capture program is 64 KB
The default memory size for Q Apply program is 2 MB
What is the attribute used to see the Message length?
The attribute used to see the message length is MaxMsgLength
What is CCDT file on WebSphere MQ or WMQ ?
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.
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
Explain what are the Types of messages?
MQ messages types are:
Datagram – It is an unsolicited message
Request – A message for which a response is expected
Reply – A message event such as a confirmation on arrival or delivery. It can be an error
MQ messages can be persistent or non-persisten
What is SSLPEER in IBM Web sphere MQ?
Another interesting and frequently asked Web Sphere 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.