I had been avoiding Google Web Toolkit , a unique Open Source offering. Then I needed to write a fancy web app quickly. GWT Rules!
GWT provides the UI classes and the hooks like HTTP calls and JSON translation necessary for the web-based client-server app-on-a-page which are standard now.
The GWT project often re-iterates the intent to stay simple and core. GWT is stimulating an outpouring of creative support and extension libraries for server support, for visual presentation, and for integration with other development tools and IDEs.