Light J2EE Application High Level Architecture Diagram

For Web Application, industry are pretty close agree to use light J2EE (Spring + hibernate) loose coupling concepts in business logic tier. However, there are not clear blueprint for presentation tie. Do we still need use thin-client or rich-client? I believe it is time to move (at least think) rich client. In here, I introduce a model for thick client:

1: Download Client-side application to user browser. (For example: extjs)
2: Client-side logic flow
3: Data exchange through AJAX in JSON format (client-server event driver)

For thin client, we can not respect "data" exchange between client and server. Maybe it just a kind of "String" exchange. For thick client, it is real data (JSON).

Reference:
1: Put JSF to work -- Build a real-world Web application with JavaServer Faces, the Spring Framework, and Hibernate; Derek Yang Shen, JavaWorld.com;