Hot Skills: Google Web Toolkit offers an easy route to Javascript

Hot skills: Ajax-based framework simplifies Java development

Hot skills: Ajax-based framework simplifies Java development

What is it?

The Google Web Toolkit (GWT) is an Ajax development framework for Java programmers. They write their program front-ends in Java, and the GWT compiler converts it to browser-compliant Javascript and HTML.

Google says, "GWT is for developers who don't speak browser quirks as a second language," and GWT applications do not necessarily "break the back button" - one of the big objections to Ajax.

GWT is downloadable free, with open source licensed source code for the libraries.

When Google previewed GWT at the JavaOne 2006 event, it was with a lack of fanfare typical of the take-it-or-leave-it attitude the company adopts to its applications. Less easy to understand is the lack of media attention the preview received, since Google is the originator of the most widely used Ajax-developed applications - Google Mail, Google Groups, Google Suggest and Google Maps.

What's it for?

Ajax applications can be developed and debugged using Java integrated development environments (IDEs) and other development tools of choice. There are four major components of GWT: a Java-to-Javascript compiler; a "hosted" web browser that enables applications under development to execute as Java in the Java Virtual Machine without compiling to Javascript; and two Java class libraries.

The Java Runtime Environment emulation library has Javascript implementations of the most widely used Java standard classes, and the GWT web user interface class library has custom interfaces and classes to create web browser widgets such as buttons, text boxes and images. The libraries can be supplemented with handwritten Javascript using a native interface.

At least one plug-in has been released, allowing GWT projects to be set up within the Eclipse IDE.

What makes it special?

Google claims GWT-generated Javascript applications are similar in size to, and almost always as fast as, handwritten Ajax. Since code in development runs in the Java Virtual Machine, developers have access to full-featured Java debugging. And because developers are not tied up with browser compatibility issues and debugging, they can devote more time to functionality.

How difficult is it to master?

GWT is supposed to take care of all the complexities of developing Ajax applications, allowing developers to work with familiar Java tools. They simply confirm that the application works with each additional browser, which usually takes no additional work.

What systems does it run on?

GWT automatically supports Internet Explorer, Firefox, Mozilla, Safari and Opera. Google's download site offers only Windows and Linux, but according to bloggers, the Linux version can be run on the Macintosh, with some limitations.

What's coming up?

GWT is currently in beta and Google warns, "You should expect the APIs to change in upcoming versions," and outdated versions will not be supported.

Rates of pay

Java developers earn an average of £46,430, although financial services firms often pay higher rates.


Dowloads, the getting Started Guide, and other resources are on Google. Several unofficial GWT sites exist, offering user guides, alternative libraries and news.

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