(ZOS) Messaging flow for JCA MDBs on z/OS with service integration
The WebSphere Application Server default messaging provider (service integration) supports the JCA resource adapter (RA) mechanism on z/OS. When we install a message-driven bean application we 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, WAS can drive workload management directly from the CRA.
Figure 1. Service integration bus: message-driven bean processing
Processing is as follows:
- A message arrives at a WAS 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.
Subtopics
- Default messaging provider activation specifications and workload management on WAS for z/OS
Workload management (WLM) enables messages to be processed in a certain order based upon transaction class. With default messaging provider (service integration) activation specifications, workload management is always active.