Typical JEE Project & Package Structure

Here is a typical structure for the Project and Packages of a JEE Web App:

Presentation Layer (Web project)

• contains the UI e.g JSF pages and beans etc
• only able to access the implementation of the project via the Control project
• actions ('do' methods) are used to trigger use cases
• does not contain any logic or calculations to remain swappable with an alternative UI

Business Layer (Control)

• contains the transactional business logic operations whose pre-conditions are validated
  encapsulates any 'finder' methods required by the Web project
• communicates with the Service project for CRUD operations

Persistence Layer (Service)

• services all operations on persisted data using ORM mapping
  contains no business logic

Domain Layer (Common)

• does not contain any methods other than those provided by the utils package
• domain objects simply represent state and are passed through the layers of the system
• the project is likely exported as a JAR file in a UML-Java transaformation to force any updates to change the domain model