(ZOS) Message listener service on z/OS

On the z/OS platform, the message listener service implementation uses the scalable server architecture to divide the listener port functions between the controller and servant processes.

A single message listener is registered in the controller portion of the ListenerPort, whereas application dispatch (that is, dispatch of the user application onMessage(Message) EJB method) is spread across the various servants comprising the server. This implementation is referred to as listening in the controller for the message-driven bean messages.

The WebSphere Application Server for z/OS message listener service implementation does not use the listening in the controller internal configuration in all cases, but only when the message-driven bean is mapped to a queue (that is, listening on a queue) or mapped (listening) to a topic through a durable subscription.

If the message-driven bean is listening to a topic through a non-durable subscription, the listener port registers a listener in each servant, rather than registering a single listener in the controller. In this case, a single message published to that topic is dispatched once for each servant comprising the server. If a message-driven bean is listening on a queue, or to a topic through a durable subscription, a single message sent is dispatched once only, to a single servant, for the entire server.

(ZOS) The configuration of the listener port, in the listening in the controller case, is administered externally through the controls described in (ZOS) Tune message-driven bean processing on z/OS using IBM MQ as the messaging provider in ASF mode and (ZOS) Message-driven beans and tuning settings on z/OS.

For a non-durable subscription message-driven bean that is listening in each servant, the listener ports are configured in the same manner as they are on distributed platforms. In this case, the single set of settings configured for the listener port are applied identically to each servant.

Manage message listener resources for message-driven beans

Message listener service