Appendix B. State and Sequence Diagrams

The appendix contains state and sequence diagrams for all the bean types discussed in this book: container-managed and bean-managed entity beans, and stateless and stateful session beans. Although standard UML is used in these diagrams, some extensions were required to model EJB runtime characteristics. In the state diagrams, for example, actions of the client and container are shown in the standard format; callback methods and class instantiation operations are shown as part of the transition event. The separation of client and container requires this simple extension.

In the sequence diagrams, container-provided classes such as the container itself, EJB object, and EJB home are shown as separate classes but are also boxed together. Messages sent from classes in the container system box are considered to be sent from the container system as a whole, not necessarily the specific container-provided class. This generalization is necessary because the container’s interaction with the bean is characterized by these classes but will be different from one vendor’s implementation to the next. The exact source of the message is immaterial, as long as you realize that the container system sent it.

Entity Beans

Life Cycle State Diagram of the Entity Bean

Life cycle state diagram of the entity bean

Figure B-1. Life cycle state diagram of the entity bean

Sequence Diagrams for Container-Managed Persistence ...

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