
In the past, two-tier applications (commonly known as client/server applications)
were very common. In a two-tier application the client side logic is responsible
for everything from presentation, business logic to database access. The
client/server applications are not scalable, are difficult to maintain and
enhance due to tight coupling between the presentation layer, business logic
and the database access. Overall the two tier applications are not scalable
and are not suitable for Internet based applications.
With the growing popularity of J2EE framework, the development of an n-tier
application became easier and all the negatives of a two-tier application
were addressed. A J2EE framework provides standardized modular components
and a complete set of services to those components. Moreover, application
behavior such as security and multithreading are handled automatically.
Using J2EE to develop n-tier applications involves breaking the two-tier
architecture into multiple tiers. An n-tier application can provide separate
layers for each of the following services - Presentation Layer, Dynamic
Presentation, Business logic, and Data base access. A browser takes care
of the presentation layer, and JSP / Servlets / XML / SOAP and XSL take
care of the dynamic presentation, Session EJB takes care of the business
logic and Entity beans take care of the data access using JDBC.
The layered approach allows each layer to focus on a specific role -- for
example, allowing a Web server to serve web pages, an application server
to serve applications, and a database server to serve databases.
With the benefit of an n-tier architecture and Axiom’s expertise on
the J2EE framework, the team at Axiom can deliver unprecedented levels of
value to customers.