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A mini book deserves a mini review, and so it is with the “Digital Shortcut” from January 2007 entitled Google™ Web Toolkit Solutions (Digital Short Cut): Cool & Useful Stuff. The 112 page PDF goes further than any of the free tutorials out there in that it develops two non-trivial applications using GWT: a Yahoo! Trips app that uses proxied Yahoo web services, and an Address Book, that makes use of Hibernate persistence through RPC.

The applications are non-trivial in that they tackle complex use cases, backend processing, web service, backend persistence and the integration of third party Javascript frameworks — all aspects of GWT application development that are of great interest to serious developers. (Source code available for download.) In order, the chapters cover the following:

1. Chapter 1 covers what must already be fairly familiar to most GWT developers — making an RPC call to a backend servlet. This chapter, however, does an exceptionally good job of explaining the why and how of GWT RPC in exhaustive detail. The Yahoo Trips application is used to illustrate how to proxy an RSS feed.
2. Chapter 2 shows how to integrate third party Javascript libraries with GWT. In this case Scriptaculous is used to provide an effect in the Yahoo Trips application to the panel containing the search results. The chapter focuses on two ways to incorporate scripts in the app — simply including script tags in the application html file, and GWT script injection, i.e. through the GWT config file.
3. Chapter 3 shows one way of how to implement drag and drop with GWT, using a fairly OO approach. The code seems pretty reusable and useful. Again, the Yahoo! Trips app is used.
4. Chapter 4 shows how to bring GWT into the mix. Most of it is old hat for experienced Hibernate hands, but the example does work through implementing a sort of remote DAO using the GWT RPC. It’s always good to see how that is done, even if it looks simple on paper. The Address Book app is used for this example.
5. Chapter 5 shows how to use ant to deploy your apps to Tomcat. I assume most everyone is using Googlipse or some non-free alternative, but writing ant files for automated build environments is still a useful thing to know.
6. Chapter 6 illustrates the use of popups and “deferred commands.” Popups are obvious (modal and modeless dialogs); deferred commands are a way of giving focus to widgets that have not yet been displayed. I really haven’t seen good treatment of this aspect of GWT programming elsewhere. Uses the Address Book app for this example.

Over all, the book doesn’t skimp on explanations and code samples and is written in a clear style. It doesn’t address unit testing with JUnit, but I suppose you can get that information elsewhere. For those of you who like to learn by doing, this is a decent tutorial (and worth the $10 price tag) that can tide you over until the bigger GWT tomes come out.