Originally posted by Chris Boldon: Does this book mostly cover new implementation, or does it also cover legacy implementation?
It doesn't explicitly cover legacy implementation, but I don't know that we could given the number of possibilities. What we do cover is the entire toolkit from soup to nuts. This includes tools like GWT-RPC for integration with Java servers, JSON-RPC for integration with non-Java servers, FormPanel useful for use with Struts, JSNI for integrating with existing JS code, etc.
So even if you are planning on using GWT to spruce up an existing app, I think that the book can still help you achieve that goal.