Configuring a Many-to-Many Relationship

In a many-to-many relationship, entity bean instances may be related to multiple instances of each other.

You specify a container-managed many-to-many relationship in the ejb-jar.xml deployment descriptor (see "Using Deployment XML").

For more information, see "Configuring a Container-Managed Relationship Field for an EJB 2.1 Entity Bean With Container-Managed Persistence".

Using Deployment XML

Example 14-11 shows the pair of <ejb-relationship-role> elements that define a many-to-many relationship between Teams and Players.

Example 14-11 ejb-jar.xml for an EJB 2.1 Many-to-Many Relationship

...
<relationships>
    <ejb-relation>
        <ejb-relationship-role>
            <ejb-relationship-role-name>team-has-players</ejb-relationship-role-name>
            <multiplicity>Many</multiplicity>
            <relationship-role-source>
                <ejb-name>TeamEJB</ejb-name>
            </relationship-role-source>
            <cmr-field>
                <cmr-field-name>players</cmr-field-name>
                <cmr-field-type>java.util.Collection</cmr-field-type>
            </cmr-field>
        </ejb-relationship-role>
        <ejb-relationship-role>
            <ejb-relationship-role-name>player-has-teams</ejb-relationship-role-name>
            <multiplicity>Many</multiplicity>
            <relationship-role-source>
                <ejb-name>PlayerEJB</ejb-name>
            </relationship-role-source>
            <cmr-field>
                <cmr-field-name>teams</cmr-field-name>
                <cmr-field-type>java.util.Collection</cmr-field-type>
            </cmr-field>
        </ejb-relationship-role>
    </ejb-relation>
...
<relationships>