Are there any good examples of how to handle one-to-many, many-to-one, and many-to-many entity bean relationships?

Alex Chaffee

The EJB spec does not specify how to deal with relationships. You'll have to develop your own Java classes to handle these design patterns.

Francesco Mondora points us to an IBM RedBook on EJB Development using VisualAge (chapter 10),

The itso.bank.ejb.relation package includes two classes (ManyLink and SingleLink) that support implementing persistent one-to-many associations between entity beans depending on storing and retrieving primary or foreign key values in a database. The one-to-many relationships are mapped to backward pointing foreign-key references.

Class ManyLink implements the multi-value association end. Depending on the relation type parameter in the constructor, ManyLink supports an aggregation association (the parent controls the live cycles of its children) or a normal association.

Class SingleLink is the single-valued inverse association end of the one-to-many relationship.

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