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Keywords: Flash, Rich Internet Applications, web applications Title: Programming Flex 2 Author: Chafic Kazoun and Joey Lott Publisher: O'Reilly ISBN: 059652689X Media: Book Level: Introductory Verdict: Doesn't quite live up to expectations.

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The move towards rich internet applications (RIA) seems to be unstoppable. Aiming to offer browser-based applications with the speed, flexibility and functionality of traditional desktop applications, companies like Google and others continue to raise the bar as to what you can do in a browser. One of the key technologies in this area has been Ajax, but even with the proliferation of Ajax toolkits and frameworks, there are an increasing range of alternatives. These include JavaFX from Sun, JBoss Seam, Google's GWT and Microsoft's Silverlight.

And, of course, there's Adobe's Flash platform, with it's massive installed user base and widespread availability of browser plug-ins. Flex 2 is that latest version of the software development kit (SDK) for producing rich internet apps targeting Flash Player 9 run-time environment. Using a combination of an XML based language called MXML and the ActionScript 3 scripting language, Flex 2 enables developers to create highly interactive GUI applications, with a high degree of functionality, linking back-end databases, business logic and user interaction all within the confines of the Flash player (normally hosted in a browser).

Given these different components, along with details of the FlexBuilder development environment, there's a lot for the new developer to get to grips with. Unfortunately 'Programming Flex 2' doesn't quite do justice to the topic. It starts out slowly, with details of the history of Flex, a detailed introduction to the architecture of Flex and so on. It isn't till chapter 3 that you get a chance to see some action, and even then it's fairly slow going. If ever a topic was geared to some gee-whizzery and flashy (ahem!) examples it's this one, but unfortunately you don't really get them here.

The chapter on ActionScript is fairly brief, the authors assume (rightly or wrongly), that readers already have some background on the language, else they recommend the purchase of a separate book on it. Given the similarities between ActionScript and JavaScript, Java and other object oriented languages the authors don't really make the most of helping readers along by pointing out areas of overlap or difference. There's also an assumed knowledge of object orientation, again, if you're not up on this then you'll have to look elsewhere for more information.

However, if you're looking for information on specific topics rather than extended tutorials, there's a lot of material covered here. Form validation, data binding, application skinning, layout managers, custom components, remote data communications and more all get chapters devoted to them. While the writing is a bit on the wordy side, the explanations tend to be clear and there's plenty of sample code (both in MXML and ActionScript) to learn from. Note that the emphasis is pretty much on key concepts and basic use cases, in the same way that this isn't a tutorial, it's also not a reference book.

Ultimately it feels as though this is a book that is aimed at a narrow band of readers. It's not for those new to ActionScript, not for those unfamiliar with object orientation and not for those looking for a technical reference. In many respects this is a book that's aimed at those who have already picked up the basics of Flex 2 and now want to get into more of the details on specific topics. If that's the position you're in then this might be the book you're looking for.