Concepts
Overview
Clusters are connected processors in a network. Processors connected in this way can support each other, and gain access to a wider range of programs and data.
With clusters, each queue manager is independent and local, and communication is enabled using transmission queues and channels.
An alternative to clusters is distributed queuing, where when any queue manager can send a message to any other queue manager in the same cluster without transmission queues and channel definitions for each destination.
Every queue manager in a cluster has a single transmission queue from which it can transmit messages to any other queue manager in the cluster. Each queue manager in a cluster needs to define only:
- One cluster-receiver channel on which to receive messages
- One cluster-sender channel with which it introduces itself and learns about the cluster
Cluster Example
Assume a cluster with three queue managers, PARIS, LONDON, and AMSTERDAM.
- PARIS hosts a full repository of information about the queue managers in the cluster.
- LONDON and AMSTERDAM host cluster queues accessible to each other's queue manager.
An application such as amqsput can MQPUT messages on a cluster queue at any queue manager. An application such as amqsget can then MQGET messages from a cluster queue on the local queue manager.
Each queue manager has a definition for a cluster-receiver channel called TO.qmgr, which carrys messages and information about the cluster.
Each queue manager also has a definition for a cluster-sender channel.
For example, PARIS and AMSTERDAM have cluster-sender channels connecting to TO.LONDON. LONDON has a cluster-sender channel connecting to TO.PARIS.
The channel starts automatically once both the cluster-receiver and cluster-sender ends of channel have been defined,