The business layer typically contains all the business logic in an application. Spring Framework is used in this layer to wire beans together.

This is also the layer where the boundary of transaction management begins. Transaction management can be implemented using Spring AOP or AspectJ. A decade back, Enterprise Java Beans (EJB) were the most popular approach to implement your business layer. With its lightweight nature, Spring is now the framework of choice for the business layer.

EJB3 is much simpler than EJB2. However, EJB3 is finding it difficult to recover the ground lost to Spring.