Facade and Service layers

[mpiatka]

• All the classes must be wired via dependency injection. Your service objects should obtain an instance of the EntityManager that way;

• All the facade interfaces must not reference entities, but Transfer Objects only;

• All service interfaces must reference only entities, not Data Transfer Objects;
  You can use Dozer framework to map entity instances to transfer objects. The mapping may be done on Facade Layer;

• Facade layer is used to drive transactions;

• Facade layer will use Service layer and Service layer will use DAO layer;

• Make sure that DataAccessException or its subclass is thrown in case of any exception on a the DAO layer;