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An overview of the entities in the system in

Figure 1

shows that there are four distinct

entities:

User

,

Group

,

Role

, and

UserInfo

. Each of these entities have the following

three relationships:

Users are associated with Roles (many to many)

A User has UserInfo (one to one)

A Group contains Users (one to many)

Each of these entities would likely have its own table in a relational database as well as

a table for any of the many to many relationships. Thus, this example application

consists of five tables, as modelled on using a relational database.

Application design: Client access system via Session

bean

All of the entity beans in this example are local entity beans. Local beans can not be

access by remote clients. They can not be returned from a method either. Thus all

access to the entities in this example is done through a session bean that acts as a

mediator between the client and the entity beans in this example (see ).

Figure 2: Diagram of operations and associations

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Introducing EJB CMP/CMR, Part 1 of 2