Cloned brokers

A cloned broker is a broker for which you have defined one or more clones; the subscription table of a cloned broker is replicated to all other brokers with which it is cloned.

When a subscriber requests a subscription from a cloned broker, the subscription is also sent to each of the clones of that broker.

Use cloned brokers to improve the availability of your publish/subscribe system. By defining cloned brokers on different computers, you make sure that a publication is delivered to a subscriber even when one of the computers is unavailable.

The diagram shows what happens when Subscriber 1 sends a subscription to Broker 1, but Broker 1 becomes unavailable; because Broker 1 and Broker 2 have been defined as clones, the subscription is redirected to Broker 2 and Subscriber 1 gets the publication from Broker 2 instead of Broker 1.

Subscriber 1 sends a subscription to Broker 1 but the broker becomes unavailable; because Broker 1 and Broker 2 are clones, the subscription is redirected to Broker 2 and the publication is received from Broker 2 instead of from Broker 1.

If two brokers are clones within a collective, duplicate messages might be sent to subscribers that are registered with brokers inside that collective.

Use the mqsichangeproperties command to define cloned brokers; the property clonedPubSubBrokerList is used to do this.

Related concepts
Subscribers
Subscriptions
Brokers
Related tasks
Setting up cloned brokers
Adding a cloned broker
Deleting a cloned broker
Related reference
mqsichangeproperties command