Architecting Modern Java EE Applications

Packages

Let's have a closer look at the boundary package. The idea was that all business use cases called from the frontend or outside of the system are initiated here. Invocations for creation, update, or deletion of users, first land in classes residing in this package. Depending on the complexity of the use cases, the boundary either completely handles the logic itself or delegates into the control before becoming too complex.

For a Java enterprise application, classes in the boundary package are implemented as managed beans. As mentioned before, typically EJBs are used here.

If the logic in the boundary becomes too complex and not manageable within a single class anymore, we refactor the logic into delegates that are used in the boundary. ...