Now that you understand the rationale and intent of patterns, how can you apply them to your J2EE applications? To do this, you must understand the J2EE design context, and you must also become familiar with the patterns themselves.
Applying Patterns in a Context
Most of the patterns defined for the J2EE platform range between the design and architecture levels. You may be able to apply individual patterns in different styles of architecture, but as a pattern language, the current J2EE patterns are squarely targeted at a 3-tier, Web-based business system. The 3 tiers are usually classified as the presentation or Web tier, the middle or business tier, and the integration or data tier.
As well as consisting of multiple tiers, ...