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Enterprise JavaBeans, Second Edition
book

Enterprise JavaBeans, Second Edition

by Richard Monson-Haefel
September 2001
Intermediate to advanced content levelIntermediate to advanced
489 pages
14h 44m
English
O'Reilly Media, Inc.
Content preview from Enterprise JavaBeans, Second Edition

Avoid Chaining Stateful Session Beans

In developing session-only systems you will be tempted to use stateful session beans from inside other stateful session beans. While this appears to be a good modeling approach, it’s problematic. Chaining stateful session beans can lead to problems when beans time out or throw exceptions that cause them to become invalid. Figure 9.1 shows a chain of stateful session beans, each of which maintains conversational state that other beans depend on to complete an operation encapsulated by bean A.

Chain of stateful session beans

Figure 9-1. Chain of stateful session beans

If any one of the beans in this chain times out, say bean B, the conversational state trailing that bean is lost. If this conversational state was built up over a long time, considerable work can be lost. The chain of stateful session beans is only as strong as its weakest link. If one bean times out or becomes invalid, the entire conversational state on which bean A depends becomes invalid. Avoid chaining stateful session beans.

Using stateless session beans from within stateful session beans is not a problem, because a stateless session bean does not maintain any conversational state. Use stateless session beans from within stateful session beans as much as you need.

Using a stateful session bean from within a stateless session bean is almost nonsensical because the benefit of the stateful session bean’s conversational ...

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Publisher Resources

ISBN: 1565928695Supplemental ContentCatalog PageErrata