Java Server Pages (JSPs) can easily tempt you into what Bitter Java refers to as the Monolithic JSP antipattern.

The solution to this is the Model-View-Controller (MVC) pattern. The Struts framework exists to help you implement this.

Struts, an open-source MVC implementation is an excellent introduction to Struts and the MVC pattern. It also covers tag libraries - J2EE's way of avoiding the ugly mixture of HTML and Java which can easily result from JSP development.

The example shows a typical Monolithic JSP refactorerd into three simple components, only one of them Java code. Beautiful.

Struts and Tiles aid component-based development covers updates to the Struts framework between versions 0.9 and 1.1.