The Google Web Toolkit (code.google.com/webtoolkit) is a free, open-source framework created by Google to make Ajax easier. In this article, we present GWTFlow, a mash-up photo viewer that lets you browse any Flickr photo album. The UI was inspired by Apple's Cover Flow album viewer (www.apple.com/itunes/jukebox/coverflow.html) and the Carousel mode in the .Mac Web Gallery. The complete source code is available online (see "Resource Center," page 5 and at www.adamhoughton.com/GWTFlow). By studying this application, you will learn useful techniques for creating your own dynamic web pages using GWT.
By standardizing on one language, you can share code on the client and server. For example, you can run the same validation codeonce on the client for immediate feedback, and once on the server for maximum security. You can even move code between tiers as you refactor applications to adapt to changing requirements.