Message-driven beans - listener port components
The WebSphere® Application Server support for message-driven beans deployed against listener ports is based on JMS message listeners and the message listener service, and builds on the application server facility (ASF) support in the JMS provider.
The main components of WebSphere Application Server support for message-driven beans are shown in the following figure and described after the figure:
The message listener service is an extension to the JMS functions of the JMS provider and provides a listener manager, which controls and monitors one or more JMS listeners. Each listener monitors either a JMS queue destination (for point-to-point messaging) or a JMS topic destination (for publish/subscribe messaging).
A connection factory is used to create connections with the JMS provider for a specific JMS queue or topic destination. Each connection factory encapsulates the configuration parameters needed to create a connection to a JMS destination.
A listener port defines the association between a connection factory, a destination, and a deployed message-driven bean. Listener ports are used to simplify the administration of the associations between these resources.
When you deploy a message-driven bean, you associate the bean with a listener port. When a message arrives on the destination, the listener passes the message to a new instance of a message-driven bean for processing.
- Creating a JMS server session pool, and allocating JMS server sessions and session threads for incoming messages.
- Interfacing with JMS ASF to create JMS connection consumers to listen for incoming messages.
- If specified, starting a transaction and requesting that it is committed (or rolled back) when the EJB method has completed.
- Processing incoming messages by invoking the onMessage() method of the specified enterprise bean.