The business tier consists of components that provide the business logic for an application. Business logic is code that provides functionality to a particular business domain, like the financial industry, or an e-commerce site. In a properly designed enterprise application, the core functionality exists in the business tier components.
The following Java EE technologies are used in the business tier in Java EE applications:
Enterprise JavaBeans (enterprise bean) components
JAX-RS RESTful web services
JAX-WS web service endpoints
Java Persistence API entities