The Five Tiers in Java EE
by, 11-19-2011 at 06:57 PM (3449 Views)
This post briefly explains the 5 tiers in Java Enterprise Edition.
A web browser, a hand held device or an application which remotely accesses the services of an enterprise application are examples of a Client tier. In other words a Client tier can consists of all the types of components that are clients of an enterprise application.
Filters, Java Servlets, JavaServer Pages, JavaBeans and other utility classes are the components that make up a Presentation tier. A Presentation tier does following. It encapsulates presentation logic and interfaces with a client tier. It accepts requests and sends appropriate response to client. It handles authentication and authorization. It manages client sessions. It delegates the business processing to the business tier.
This tier is at the crux of enterprise application. Enterprise JavaBeans components are normally part of business tier. Business tier implements core business services.
Integration tier is in between Business tier and Resource tier. And as name suggests it integrates different types of external resources in Business tier with the components of business tier. The components that make up the integration tier use different mechanisms such as Java EE connector technology, JDBC etc.
The resource can be data storage or some type of a system. For example a relational database, a file based database etc are a Resource. Or it can be a system viz. an application running on mainframes, new age B2B systems etc. A resource can also be a third party system such as credit card authorization system. That is Resource tier consists of the external resources that provide the actual data to the enterprise application.