The book's 17 chapters are organized into four parts, and cover a generous number of topics: introduction to GWT; creating the default GWT application; building your own application based upon the default one; creating widgets and panels, including composite panels; processing user events; creating JSNI components; modularizing your code; communicating using GWT-RPC; client-side RPC; classic Ajax and HTML forms; using JSON for interoperability; automatically generating code; GWT's native properties; testing and deploying GWT applications; more on the inner workings of GWT itself. The book has no appendices, but a substantial index, which is essential for such a technically detailed subject area.
GWT in Action is clearly intended to be a practical and fairly comprehensive coverage of Google's new toolkit. Almost all of the GWT concepts are explained within the context of developing a substantial sample application, the Dashboard, created by the authors. The reader is encouraged to follow along as the authors build the application, thereby learning from doing — almost always an effective approach. At 600 pages, with almost none of the formatting padding found in far too many technical books nowadays, the authors have not skimped on providing the reader with a lot of information. Furthermore, their treatment of application deployment is far better than any other I have encountered.
Unfortunately, the book has many weaknesses. On an overall basis, the order of presentation is at times disjointed — seemingly dictated more by the Dashboard and less by the most logical order for someone new to GWT. Compounding the problem, the authors frequently refer to advanced topics, covered in greater detail later, and also repeat earlier information, occasionally several times. Despite promises to provide a gentle exposition, it can be difficult at times for the reader to determine if any critical steps were skipped, as a consequence of key instructions for building the sample application being spread out, and interspersed with too many references to general comments covered earlier. In turn, readers will likely find it frustrating to try to get the sample application working at each step of the development process — and not just at the end, with the complete code.
We can mention some specific flaws: A book like this that is introducing a new technology, must take care to not leave the unwarned reader wondering if they have been left behind in the steps. People reading some of the earlier material may conclude that those steps have already been assumed by the authors, and will not be covered. The authors do not mention how to obtain and install GWT until page 30; that should be right up front. The authors do not appear to mention which version of GWT they used for the book. (I chose 1.3, not 1.4RC, available as of this writing). Any reader trying to follow along and implement their example application (the Dashboard) will probably find several hurdles. First of all, make sure that you have version 1.4 of GWT installed, and not 1.3.3, which does not include some of the panels and widgets used in their sample code.
In Chapter 1, they modify a "Hello world" application to create another application that shows a tic-tac-toe board that has clickable squares, but does not play the game. Chapter 2 describes this as "a fully functioning Tic-Tac-Toe application," which is like claiming a program works because it compiles. Also in Chapter 2, their discussion of development alternatives is slowed down by repetition of the same information. The sample code in the book has minor inconsistencies. For example, naming a password String "oldPass" in one method, then "old" in another, related method. There are other instances, but these give one an idea of some of the inconsistencies.
The coverage of topics is generally quite thorough, though at times verbose and redundant — particularly in Chapter 2, though it is certainly not limited to that chapter. The second and third paragraphs in Chapter 3, for instance, continue the repetitious style which is found in many places throughout the book, and likely has made it longer than necessary. In Chapter 4, the first two pages explain what widgets are, several times, and conclude with a picture of a button — as if any reader who has made it that far into the book doesn't know what a button is. The book could certainly use some trimming.
The downloadable source code is not complete. For starters, it is missing the code from Chapters 1 and 2, though admittedly none of that is too long. The code provided for Chapter 4 is just a portion of what is displayed in the book. Moreover, the directory paths in the sample code archive files, are not consistently named, and some may even be incorrect. For example, the code for Chapter 5 has a folder named "Dashboard — Chapter 4." That sort of thing does not instill confidence in the typical reader. The authors should revisit the sample code — making it complete and consistently named.
The publisher's page for the book does not appear to have a link for errata; perhaps none have been reported yet. Here are some: On page 75, in Table 3.1, in the left-hand column, "gwt-onLoadErrorFn" should instead read ""gwt:onLoadErrorFn." On page 77, in the second paragraph, the file name extension should be all lowercase, not all uppercase. On page 78, in Listing 3.6, the String parameter in the first label.setText() call should be delimited with straight quotes, not curly quotes. (Microsoft Word strikes again?!) On page 81, in the third paragraph, "comply to" should read "comply with." On pages 87 and 88, the -whitelist and -blacklist option values each contain an extraneous space before the "^." There are undoubtedly more such errata throughout the book, and can be corrected in the next edition; but these are enough to at least get an errata file started. Fortunately, none of them would lead an alert reader astray.
Even though the book could use significant reorganization and streamlining in the next edition, GWT in Action is packed with practical information on a wide range of GWT topics.
Michael J. Ross is a Web developer, freelance writer, and the editor of PristinePlanet.com's free newsletter.
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