Checkpoint

Where We've Been

• A well-designed application requires that the logical layers be treated with care during the physical implementation to ensure that as the business evolves, a shift in either the business model or the technology framework won't leave the application in the legacy bin.

• The Presentation Services layer will change often in the life span of an application. It is crucial to separate the user interface from the implementation. Today, Web forms; tomorrow, wireless.

• The Business Context Services layer is responsible for the syntax and context editing. This logical layer will be implemented in both the user interface component and the Web server.

• The Business Rule Services layer is responsible for the many workflow issues that the application faces. This layer will contain all the entity classes, and they can be deployed on either the client or server platform.

• The deployment options could be varied (applets, Java applications), but we have chosen to use both non-EJB and EJB architecture to manage our Java components.

Where We're Going Next

In the next chapter we:

• Present some background material on Apache Tomcat and how it will be used in our example.

• Lay out the remaining sequence diagrams for the simple pathway of inquiring about a customer and updating a customer through the Maintain Relationships use-case.

• Explore ways of improving the solution over time.