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GWT in Action
Posted by
samzenpus
on Wed Aug 29, 2007 02:46 PM
from the read-all-about-it dept.
from the read-all-about-it dept.
Michael J. Ross writes "Server-side computer languages, such as Java, possess numerous advantages over their client-side counterparts — including more robust integrated development environments (IDEs). In contrast, Web-focused languages, such as JavaScript, benefit from the global accessibility of the Internet. Bridging this gap, and leveraging the strengths of both sides, has long been an objective of the software development community — though not all attempts have been successful, e.g., Java applets. The Google Web Toolkit (GWT) is the latest attempt, and shows considerable promise, as illustrated in a new book intended to help programmers learn this new technology: GWT in Action." Read on for the rest of Michael's review
| GWT in Action | |
| author | Robert Hanson and Adam Tacy |
| pages | 600 |
| publisher | Manning Publications |
| rating | 6 |
| reviewer | Michael J. Ross |
| ISBN | 1933988231 |
| summary | A practical introduction to programming with the Google Web Toolkit (GWT). |
Written by Robert Hanson and Adam Tacy, this book was published by Manning Publications on 5 June 2007, under the ISBNs 1933988231 and 978-1933988238. For any prospective reader who would like to learn more about the book, they can first try the book's Web page, where they will find online versions of the "about this book" section, table of contents, preface, and index. The publisher offers two freely downloadable chapters, "Creating the Default Application" and "Communicating with GWT-RPC," in PDF format. In addition, there is a link to purchase the book's electronic version, and a link to the author's forum, where readers can post questions about the book or GWT, and likely receive a response — perhaps even by one of the authors.
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.
One source of these difficulties, is that in the first few chapters, the authors try to introduce too many topics all at once, and as a result do not thoroughly discuss each one in its own section. Instead, they break up the information over multiple sections, scattered throughout the book. An example of this is internationalization. Section 2.2.4 is titled "Implementing Internationalization," and yet provides almost no details, and is essentially unusable by itself. At the very least, it should mention that later sections 3.2.1 and 15.3 provide a lot more information. Furthermore, internationalization was introduced far too early in the book, and greatly complicates the process. Instead, the authors should have created a simple application using only English for the user interface, and introduce internationalization later, after fully explaining the basics of turning Java code into JavaScript functionality.
Part I of the book is the weakest of all of them, which may, sadly, turn off readers who would otherwise get to the better material later. The authors are clearly enthusiastic about the topics at hand, and the number of moving parts associated with Java/JavaScript/GWT development is certainly not trivial. Nonetheless, those initial chapters would greatly benefit from a rewrite; this would make the material more comprehensible and easier to follow, step-by-step.
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.
You can purchase GWT in Action from amazon.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
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.
One source of these difficulties, is that in the first few chapters, the authors try to introduce too many topics all at once, and as a result do not thoroughly discuss each one in its own section. Instead, they break up the information over multiple sections, scattered throughout the book. An example of this is internationalization. Section 2.2.4 is titled "Implementing Internationalization," and yet provides almost no details, and is essentially unusable by itself. At the very least, it should mention that later sections 3.2.1 and 15.3 provide a lot more information. Furthermore, internationalization was introduced far too early in the book, and greatly complicates the process. Instead, the authors should have created a simple application using only English for the user interface, and introduce internationalization later, after fully explaining the basics of turning Java code into JavaScript functionality.
Part I of the book is the weakest of all of them, which may, sadly, turn off readers who would otherwise get to the better material later. The authors are clearly enthusiastic about the topics at hand, and the number of moving parts associated with Java/JavaScript/GWT development is certainly not trivial. Nonetheless, those initial chapters would greatly benefit from a rewrite; this would make the material more comprehensible and easier to follow, step-by-step.
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.
You can purchase GWT in Action from amazon.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
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The more I learn about JavaScript... (Score:5, Insightful)
I'm not really sure I see the point of GWT, given that JavaScript is actually a more powerful language at this point. I'm almost tempted to suggest that someone build a webserver platform around a JavaScript interpreter.
Well, almost. The problem with JavaScript is that it's horribly slow to execute. But then, you still have that problem, even if it's JavaScript generated from Java code.
Re: (Score:3, Interesting)
Depends on your engine. I've put some thought into the same sort of server-side Javascript engine as you have. Someone else mentioned the Netscape Enterprise Server. That was... not so great. I was thinking more along the lines of building on top of a Java Servlet Engine. The Mozilla Rhino [mozilla.org] Javascript Engine actually compiles the JS down to Java byte code. That wouldn't be all that special, except that the JVM then JITs that to native code. Wh
Re: (Score:3, Interesting)
But then, you still have that problem, even if it's JavaScript generated from Java code.
That's not really what's going on.
GUI stuff happens in Javascript. Anything really complicated gets sent over to Java. That's why it's called an AJAX framework, not a Javascript framework.
I like Javascript, but it has the same problem as PHP: no namespaces. Using it as a real language would causes the same problems you see there: security issues, hard-to-read code, difficulty refactoring, interoperability problems, etc. You can actually see those problems and the various mechanisms to overcome them in
Re: (Score:3, Informative)
I agree with you that Javascript is a nicer language than Java and more powerful to boot, but I'm using GWT for one big reason: dead code elimination. The GWT compiler takes advantage of the static analysis possibilities in Java and the closed-world nature of a web page and produces dramatically optimized Javascript. Th
Re: (Score:3, Informative)
Not. Java doesn't have closures. Java functions aren't first-class objects.
JavaScript, OTOH, isn't typed.
There's loads of differences between them. All I'd want from JavaScript is more performance, namespaces, and possibly some very basic native OO concepts so that I can define an inherited class without three or four declarations and maybe have private and static members.
I Still don't know what GWT is (Score:5, Informative)
Beyond hope (Score:5, Insightful)
Come on, doesn't anybody read these?
Re:Beyond hope (Score:5, Funny)
Parent
GWT *and* Java (Score:5, Informative)
Before somebody grills me, the version of WindowBuilder Pro that I am using is a bit unstable and crashes Eclipse now and then. Lots of memory is also recommended (then again, if you are a developer, you need lots of memory anyway).
Re: (Score:3, Informative)
Nah, didn't think so
Why should GWT be on my radar screen? (Score:3, Insightful)
I want to write desktop apps with JS/GWT/whatever (Score:3, Interesting)
JS is a great language and GWT is a great tool, especially the hosted development environment. But it will never reach its potential until it is a general purpose application programming language.
Very nice toolkit with some problems (Score:4, Informative)
The content on Google's GWT site [google.com] almost speaks for itself concerning the power of it, so I'll elaborate on some negative aspects I've encountered.
I went to explore the possibility of a non-servlet based backend and very quickly encountered problems that are not really GWT's fault but a side effect of having a hosted environment: the browser is based on Mozilla and thus inherits the security restrictions of it. I could not make RPC calls to my backend web server because Mozilla disallows cross-domain access. I spent a lot of time trying to circumvent this, and did find some work-arounds but nothing that worked to my satisfaction (too cumbersome). GWT should offer a modified Mozilla with these restrictions removed, or even better, adopting Flash's excellent practise of looking for a crossdomain.xml [crossdomainxml.org] file in the root of the target webserver (to see whether access is allowed or not).
Also, developing on an AMD64 based Linux I discovered that the hosting environment just doesn't work running from a 64bit JVM. Setting up a 32bit JVM isn't that difficult, but it's not a good solution (However, I talked to a GWT developer on IRC who claimed this issue was high on their priority list).
Lastly, GWT is a nice environment, but it's still a bit young. It seems stable enough, but if you engage in a large GWT based project you may find yourself doing a lot of low-level client-side code unless their limited palette of widgets and other client-side features completely cover your needs
Shameless plug - chess board diagram composer (Score:4, Interesting)
Just a few hours ago I finished a small, mostly-for-fun project in GWT, and now I see a GWT-related story on slashdot. Surely it's not a coincidence and therefore I must pimp my project: a chess board diagram composer [jinchess.com].
Re:Wow (Score:5, Funny)
Parent
Re:Wow (Score:4, Interesting)
Is it just me or is anyone else glad to see a review on Slashdot without a chapter by chapter summary? One of the most pointless, pedantic mistakes in book reviews is to summarize each chapter. Hoozah for the writer!
Parent
Re:Wow (Score:4, Funny)
Don't Use Google Web Toolkit.
Parent
Worse than Wicket? (Score:4, Interesting)
I did an evaluation of it. I kind of liked it, but in general don't like "lets make a servlet environment pretend its an applet", so I didn't endorse.
Now, after months of using Wicket, I wish I had pimped for it more. Seriously. If you're gonna pretend it's an applet, then REALLY do it like GWT does, fake JVM and all. This Wicket stuff.... ugh. keeping the html view and java in synch for anythign complex is SO IRRITATING.
Seriously, after years of Struts and stuff like Wicket, I don't see any real advantage over "Model 2+" (Servlet/JSP pairs) that I started with in 2001. There is a benefit to simplicity and writing HTML in HTML and writing Javascript in Javascript that over-engineers who are, frankly, a little OO-obsessed just don't get.
Maybe years of Perl CGI has bent my brain but The HTTP Request/Response paradigm just doesn't seem so awful that it needs to be (leaky) abstracted away.
Parent
Re:Worse than Wicket? (Score:5, Insightful)
I couldn't agree more. I like my code structured, clean and simple, and layering abstraction upon abstraction is not a good way to achieve that. I'm also a big proponent of writing to the language's strengths. JavaScript has some annoying weaknesses (lack of namespaces), but things like it's object prototyping are very powerful, and it seems silly to give that up. For all the browser inconsistencies, HTML + CSS is actually quite a nice layout tool. Getting them all to work together requires some organizational skills, but it pays off in ease of use and a higher level of control.
These are tools a web developer really should be comfortable with anyway, so while I can see the utility of something like GWT if you're not, to really excel at it, you should be knowledgeable about them.
Parent
Re: (Score:3, Insightful)
You can't really write a web application using a (single) language, though; you need to have some degree of expertise in HTML and CSS AND Javascript AND whatever language(s) your server-side code is written in...
I can see some appeal in toolkits that unify everything into just one language, for the developer's convenience. It's still pretty much impossible that the output of such a toolkit will be anywhere near as elegant or efficient as nativ
Re:Worse than Wicket? (Score:4, Insightful)
Parent
Re:Worse than Wicket? (Score:4, Insightful)
Maybe especially core Wicket, which isn't trying to do much but wrap HTML bits as objects. What really is the benefit of that? Nothing seems simpler and it often seems to be getting in the way-- maybe it's a mental gap problem, but often I end up having to put placeholder HTML in the page, and the set visibility = null. And the Ajax support is so-so.
I mean, I think the fact that the static Wicket homepages often produce session timeout exceptions is pretty damning that it encourages poor web programming.
Parent
Re: (Score:3, Interesting)
Re: (Score:3, Informative)
Firstly, I had loads of problems. However they were mainly down to broken stuff in the RC builds (all fixed now that it's out of beta) and the fact that I was learning Java as I went along. Nothing that was a major problem was down to the architecture of GWT.
If i'd have written pure javascript instead then doubtless it'd have taken far longer and worked less well.
GWT rocks for anything where yo
Re: (Score:3, Interesting)