Introduction to the Java EE architecture

Modern enterprise applications are often developed using a layered architecture. The most commonly-followed architecture is a three-tiered architecture. In this model, the responsibilities of an application are divided into three layers—view, business logic, and persistence. The view or presentation layer deals with presenting a user interface and is responsible for interacting with the end user and the application. The business layer consists of the core business and the domain logic of the enterprise application. This includes the code that defines the processes to run and deals with how data is created and operated on for the business problem in question. The persistence layer defines how data is stored using a database. This three-tiered architecture is as follows:

Java EE provides services to enterprise applications that are developed using a layered architecture. Servlets, Java Server Pages (JSP), or Java Server Faces (JSF) can be used for the presentation layer of the application. Typically, these components are deployed on a web container and the end user interacts with the web container using the web browser. Enterprise Java Beans are used for the business logic of the application and run in an EJB container. The JPA, meanwhile, is used for the persistence layer of the application, which maps between entities and relational database tables. This is depicted in the following diagram: