Antonio Goncalves' Website

Architecture

What is an architecture ? Wikipedia defines it as beeing the structure or structures of the system. What I like about this definition is the plural on structures.

Too many companies see the Architecture with a upper A instead of seeing architectureS with a upper S. It's dangerous to try to homogenise all the projects of a company into a single defined architecture. Each project is different, each project has it's own needs. If you need to develop a simple web administration console used by one person twice a week, JSPs + SQL statements are fine. You would loose time, money and effort trying to homogenise this application into a defined 3-tier architecture.

Java EE 6 is rich and simple enough to be used by any kind of application. Need simple ? Do simple ! Need rich ? Add layers and components.

Structure

Any architecture has one or many layers. Each layer has a certain amount of components that could be used.

View : On the view layer, you can have any kind of graphical user interface. It goes from basic JSP, JSF pages or Swing. You could also think of others non-Java EE 6 technologies such as GWT, JavaFX or Flex
Controller : Web controllers have been implemented through Servlets, but with JSF, a Managed Bean can also be seen as a controller
Service : A service is a component that gives you a service. In Java EE 6 it is primarely a stateless session bean, but it's anything from a simple POJO, a Web Service, a Restful Service, a Stateful EJB, a Message driven bean...
Domain : Layer of business classes.
Database Access : For database access and Object/Relational mapping, JPA is the preferred persistent model in Java EE 6. But you can still use pure JDBC access or even DAOs.
Interoperability : Your system can either use external services or expose a set of services.

JSP and JDBC application

Some people would call that a quick and dirty application. They might be right, but they also might be wrong. In certain cases you just need a set of JSP pages with direct database access using JDBC result sets. It can be used for prototyping, but also for some non-critical non-concurrent application.

A simple MVC Web application

If you don't want to use JSF for your web application, you still have the choice to use the good old MVC I model : JSPs talking to Servlets that use DAOs for accessing the database and POJOs as the model. Servlets also manage the flow of your application.