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Overview of the RosterApp Application

The RosterApp application maintains the team rosters for players in sports leagues. The application has five components. The RosterAppClient component is a J2EE application client that accesses the RosterEJB session bean through the bean's remote interfaces. RosterEJB accesses three entity beans--PlayerEJB, TeamEJB, and LeagueEJB--through their local interfaces.

The entity beans use container-managed persistence and relationships. The TeamEJB and PlayerEJB entity beans have a bidirectional, many-to-many relationship. In a bidirectional relationship, each bean has a relationship field whose value identifies the related bean instance. The multiplicity of the TeamEJB-PlayerEJB relationship is many-to-many: Players who participate in more than one sport belong to multiple teams, and each team has multiple players. The LeagueEJB and TeamEJB entity beans also have a bidirectional relationship, but the multiplicity is one-to-many: A league has many teams, but a team can belong to just one league.

Figure 6-1 shows the components and relationships of the RosterApp application. The dotted lines represent the access gained through invocations of the JNDI lookup method. The solid lines represent the container-managed relationships.

Figure 6-1 RosterApp J2EE Application

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