Configuring a One-to-One Relationship

In a one-to-one relationship, an entity bean instance is related to a single instance of another entity bean.

You specify a container-managed one-to-one 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 14-8 shows the pair of <ejb-relationship-role> elements that define a one-to-one unidirectional relationship between Order and ShippingAddress. For a bidirectional relationship, you would add the appropriate cmr-field to the <ejb-relationship-role> for ShippingAddress.

Example 14-8 ejb-jar.xml for an EJB 2.1 Unidirectional One-to-One Relationship

...
<relationships>
    <ejb-relation>
        <ejb-relation-name>Order-ShippingAddress</ejb-relation-name>
        <ejb-relationship-role>
            <ejb-relationship-role-name>order-has-address</ejb-relationship-role-name>
            <multiplicity>One</multiplicity>
            <relationship-role-source>
                <ejb-name>OrderEJB</ejb-name>
            </relationship-role-source>
            <cmr-field>
                <cmr-field-name>shippingAddress</cmr-field-name>
            </cmr-field>
        </ejb-relationship-role>
        <ejb-relationship-role>
            <ejb-relationship-role-name>address-for-order</ejb-relationship-role-name>
            <multiplicity>One</multiplicity>
            <relationship-role-source>
                <ejb-name>AddressEJB</ejb-name>
            </relationship-role-source>
        </ejb-relationship-role>
    </ejb-relation>
...
<relationships>