What is MQ and what does it do?
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. MQ is platform independent for example it can be used to communicate between Java and .Net or it can be used to communicate between Java Application and TIBCO etc.
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?
- Integration.
- Asynchrony
- Assured Delivery
- Scalability.
- Workload balancing
How does it support the Integration?
Because the MQ is independent of the Operating System you use i.e. it may be Windows, Linux,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.MQ can be used for both Synchronous and Asynchronous transactions . Example of synchronous transactions are IMPS Bank transaction and Asynchronous transaction is NEFT where it can wait for few hours .
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.
- 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.
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. Non-persistent messages are not logged. WebSphere 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 non-persistent message. Message persistence will be decided by the putting application or first landing queue that has DEFPSIST value as YES .
WebSphere MQ messages:
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 Applications
What are the Objects used in Web sphere MQ?
- 1. Queue Manager
- 2. Queues
- 3. Channels
- 4. Processes
- 5. Name lists.
- 6.Topics
- 7.Subscribers
- ..etc
Mention the No of Characters required for creating names of the MQ objects?
For MQ Channels it is 20 Characters
For Remaining objects it is 48 characters.
What about is the Default port number for MQ Queue Manager?
1414
Difference between MQSC commands and Control commands?
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…