The WebSphere® Application
Server default messaging provider (service integration) supports the
JCA resource adapter (RA) mechanism on z/OS. When you install a message-driven
bean application you provide an activation specification.
The following figure illustrates the messaging flow for JCA message-driven
beans that use the service integration bus as the messaging provider.
Service integration includes a resource adapter (RA). The RA has
a listener component that runs in the control region adjunct (CRA),
and a dispatcher component that runs in each servant region (SR).
The RA dispatcher component drives the application code. For some
workloads, WebSphere Application
Server can drive workload management directly from the CRA.
Processing
is as follows:
- A message arrives at a WebSphere Application
Server running on z/OS®.
- The
messaging engine locks the message and passes it to the RA
listener component.
- The RA listener passes the message to
the WLM classifier, which
uses user-provided classification rules to determine the transaction
class of the message.
- The transaction class is attached as
context.
- The RA listener passes the message reference to the
RA dispatcher
in an SR. The figure shows this step as using the CR to pass the reference
through a WLM queue but, for some workloads, the CRA can pass the
reference through a WLM queue without using the CR.
- The RA
dispatcher reads the message from the messaging engine.
- The
RA dispatcher dispatches the message-driven bean by invoking
its onMessage method.
- The message-driven
bean can then use JMS for messaging, if required.