Enterprise Architecture

Figure depicts the J2EE as a multitier architecture.

[Figure : Multitier J2EE architecture. ]

The following gives a brief summary of each tier of the J2EE architecture:
· Client tier :-
o This tier interacts with the user.
o And displays information from the system to the user.
o J2EE supports different types of clients—both inside and outside enterprise firewalls {including Web clients (HTML and Java applets) and Java applications.}
· Web tier :-
o This tier accepts user requests.
o And generates responses using the presentation logic.
o In the J2EE platform, servlets and JSPs in a Web container implement this tier.


· Business logic tier :-
o This tier handles the core business logic of the application.
o The business components are typically implemented as EJB components.
o With support from an EJB container.
o Which provides the component life cycle
o And manages :
§ Persistence,
§ Transactions,
§ Security, and
§ Resource allocation.


· EIS tier :-
o This tier is responsible for the enterprise information systems.
o Including
§ Different database systems,
§ Transaction processing systems,
§ Legacy (inheritance)systems,
§ Message-Oriented Middleware, (MOM) and
§ Enterprise resource planning systems (ERPs).


o The EIS tier is the point at which J2EE applications integrate with non-J2EE or legacy systems.