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EJB workload management and high availability are achieved by a combination of WebSphere server cluster support and the WebSphere ORB (Object Request Broker) workload management plug-in. EJB failover depends on whether this type of EJB can be workload-managed by the container.
The workload management service provides load balancing and high availability support for the following types of EJBs:
| Homes of entity or session beans |
|
| Instances of entity beans |
|
| Instances of stateless session beans |
The only type of EJB references not subject to load distribution through EJB WLM are stateful session bean instances. However, IBM WAS ND V6 now supports stateful session bean failover as explained in 2.6.5, Stateful session bean failover.
Table 2-1 summarizes the workload management capability of different types of EJBs.
Table 2-1 Summary of EJB types and WLM
| EJB types | Component | WLM capable |
|---|---|---|
| Entity bean (Option A) | Home | Yes |
| CMP bean instance | No | |
| BMP bean instance | No | |
| Entity bean (Option B,C) | Home | Yes |
| CMP bean instance | Yes | |
| BMP bean instance | Yes | |
| Message-driven bean | Bean instance | Yes |
| Session Bean | Home | Yes |
| Stateless bean instance | Yes | |
| Stateful bean instance | No |
