A message driven bean (MDB) is a variation of the EJB stateless component model designed to run as a message consumer. For more information, see “Message-driven beans” in Chapter 2, “Setting up the Message Service,” in the Java Message Service User’s Guide.
If your MDB implementation can run concurrently on multiple threads, this configuration can significantly increase performance. EAServer by default delivers messages using a single worker thread. The default configuration guarantees first-in-first-out (FIFO) processing of messages in the queue, based on message priority: EAServer delivers messages serially to one component instance. If you do not require FIFO message ordering, customize the MDB thread settings to increase the thread count. EAServer creates several instances of the MDB, each running on a different thread to process messages concurrently.
In the Management Console, modify the MDB thread count by modifying the properties of the EJB Module that contains the MDB. For details, see Chapter 2, “Deploying and Configuring EJB Components,” in the EJB Users Guide. In a user configuration file, you can configure the thread count using the Ant <setProperties> and <messageListener> commands, for example:
<setProperties component="ejb.components.myjar.MyListener"> <messageListener queue="MyQueue" threadCount="5"/> </setProperties>
