Sun Java System Application Server Enterprise Edition 8.2 Developer's Guide

Load-Balanced Message Inflow

You can configure ActivationSpec properties of the jmsra resource adapter in the sun-ejb-jar.xml file for a message-driven bean using activation-config-property elements. Whenever a message-driven bean (EndPointFactory) is deployed, the connector runtime engine finds these properties and configures them accordingly in the resource adapter.

The Application Server transparently enables messages to be delivered in random fashion to message-driven beans having same ClientID. The ClientID is required for durable subscribers.

For nondurable subscribers in which the ClientID is not configured, all instances of a specific message-driven bean that subscribe to same topic are considered equal. When a message-driven bean is deployed to multiple instances of the Application Server, only one of the message-driven beans receives the message. If multiple distinct message-driven beans subscribe to same topic, one instance of each message-driven bean receives a copy of the message.

To support multiple consumers using the same queue, set the maxNumActiveConsumers property of the physical destination to a large value. If this property is set, the Sun Java System Message Queue software allows multiple message-driven beans to consume messages from same queue. The message is delivered randomly to the message-driven beans. If maxNumActiveConsumers is set to -1, there is no limit to the number of consumers.

The following sample application demonstrates load-balanced message inflow: