20 May, 2012 #Technology

A Brief outline on IBM Webshpere MQ (WMQ)

  • RB

IBM Websphere MQ (WMQ or MQ Series) is a middleware for messaging in a cross platform environment. MQI – Message Queue Interface – api used to commmunicate with a Message Queue Manager (MQM). 

Queue Manager (MQM) 

  • Manages queues and messages for applications 
  • Transfers messages to other Queue Managers via channels using existing network facilities. 
  • It refers to objects that are defined by the administrator.
  • Coordinates updates to databases and queues using two-phase commit. 
  • Gets and puts from/to queues are committed together with SQL updates, or backed out if necessary. 
  • Segments messages, if necessary, and assembles them. 
  • Can group messages and send them as one physical message to their destination, where they are automatically disassembled. 
  • Can send one message to more than one destination using a user-defined dynamic destination list. 
  • Allow administrators to create and delete queues, alter properties of existing queues,control the operation of queue manager. 
  • Front-end available on Eclipse to manage Queue Manager 

 Queue Manager Clusters 

  • Queue Managers that form a cluster can run in the same machine or in different
    machines on different platforms. 
  • Two of Queue Managers maintain a repository that contains information about all queue
    managers and queues in the cluster (full repository). Other Queue Managers maintain
    only a repository of the objects they are interested in (partial repository).
  • Queue Managers use special cluster channels to exchange information. 
  • Client application may specify a queue manager and direct the message to a specific
    queue in a cluster or it may let a queue manager to determine where the queue is and to
    which one to send the message. 
  • Client uses a Transmission Queue on its machine and destination queue is called “Target
  • Administrator must define the name of the cluster, when a queue is defined. 
  • MQSeries distributes the messages round robin. 

 Queue Manager Objects 

  •  A Queue Manager uses 3 types of objects, namely, Queues, Process Definitions and
  • Queues are used to store messages. 
  • Process Definition object defines an application to a queue manager. It contains a name
    of a program (and its path) to be triggered when a message arrives for it.
  • Channel is a communication link. There are 2 kinds of channels, namely, Message
    Channels and MQI channels. 
  • Message Channel connects 2 queue managers via Message Channel Agents (MCA).
    Message Channel is unidirectional. 
  • MCA is a program (also called mover) that transfers messages from a transmission
    queue to a communication link and from communication link to a target queue. 
  • MQI channel connects MQSeries client to a queue manager and is bi-directional. 
  • Message Channel can run at 2 speeds: fast and normal. Fast Channels improve
    performance but messages can be lost in case of channel failure. 

Message Queues 

  • Message Queues belong to Queue Manager. 
  • Types of Messages Queues are: 
    • Local Queue – is a real queue
    • Cluster Queue – is a local queue that is known throughout a cluster of queue
    • Remote Queue – structure describing a queue hosted by a different queue
    • Transmission Queue – a local queue used for messages to be sent to a remote
    • Initiation Queue – local queue with a special purpose 
    • Dynamic Queue – local queue created on the fly 
    • Alias Queue – if you do not like the queue name 
    • Dead-Letter Queue – one for each queue manager 
    • Reply-to Queue – specified in request message 
    • Model Queue – model for local queues 
    • Repository Queue – hold cluster information 

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