title: Where to put entity classes in three layer architecture?
body: <p>I'm required to built an application with three layer architecture. If I were to access the database in simple SQL queries, I could put domain classes in business layer and SQL queries in data layer. 
  Since I intend to use JPA to access the database, to which layer should I put the entity classes? Are entity classes, a combination of both layers? If they can be included in one layer, how can I map the to the other layer?</p>