A New Perspective on Application Layer Integration
The main purpose for all those previous steps is to decouple your components from any major dependencies. For example, you should be able to interchange the different layers of the application to work with different components without having to change how the other layers handle the interactions.
We want to keep this decoupling, but it would also be good to reduce the steps and decrease the complexity of our application by going from the Presentation layer directly to the EIS layer, without so many moving parts.
To demonstrate this, the rest of this article will give a short Login page example using JSF and a managed bean.
The development environment in this example uses Tomcat 7 as the servlet container. To work this example, you'll also need to add the jar jstl_api.jar, along with the JSF library jars to your project library; otherwise, Tomcat will not compile a JSF applications.
The back-end storage for this example is a simple properties file that holds some user credentials. The back-end storage can easily be changed to use JDBC or the Java Persistence API (JPA) to interface with a database.