To be able to tune the processing of endpoint message-driven beans (MDBs), you need to understand the concepts and considerations for the MDB settings that you configure.
When a message-driven bean is mapped (that is, listening to) a queue, or to a topic through a durable subscription, a JMS message first enters into the WebSphere server in the controller, so we say the server is "listening in the controller" for these messages. The "listening in the controller" term is used throughout this description of tuning MDB processing.
The following sub-topics provide a set of information that describe the concepts and considerations that you should be aware of to be able to configure MDB settings on z/OS:
When a message-driven bean is mapped (that is, listening to) a queue, or to a topic through a durable subscription, a JMS message first enters into the WebSphere server in the controller, so we say the server is "listening in the controller" for these messages. When a message arrives, it flows through a sequence of events.
On z/OS, the "MDB throttle" is used to control the amount of work that the server processes at a given time for a message-driven bean. The MDB throttle limits how far the message listener port will "read ahead" to try to ensure that the work request queue does not have a backlog of messages to be processed.
You can tune a variety of settings for the "MDB throttle", to control the amount of MDB work that the server processes at a given time.
You can tune a variety of connection factory settings to control the creation of connections and sessions for MDB work.
A message-driven bean can run on an application server that hosts a heterogeneous workload including other message-driven beans and non-MDB work items. To manage a heterogeneous workload on z/OS, you should use WLM classification and define unique service classes for different-priority work running in the same server.