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InfoQ Homepage News GWT 2.0 Comes with a New Performance Tool: Speed Tracer

GWT 2.0 Comes with a New Performance Tool: Speed Tracer

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GWT 2.0’s new features are: Speed Tracer – a performance analysis tool, Development Mode, UiBinder, Layout Panels and more JavaScript code size optimizations.

Speed Tracer (ST), built using GWT, is the most attractive  GWT addition. Speed Tracer is a performance analysis tool for Chrome, being used to analyze any web application, not just GWT ones. ST comes as a Chrome extension so the in-development Chrome 4.0 must be used to install it.

ST contains two main views: sluggishness and network. The first shows how responsive the UI is over time, while the second displays the network activity over the same period of time. Start/Stop/Record commands are available to facilitate analyzing a certain period.


Some other important new features in GWT 2.0 are:

Development Mode (DM)

  • A new GWT Developer Plug-in allows debugging a GWT application in any browser. That means having the ability to combine GWT debugging with the preferred tools in the browser of choice, like Firebug in Firefox.
  • Multiple different browsers can be monitored in one session.
  • DM works not just locally but also across the network to test a web application on any browser-OS combination and in a real environment.
  • A new GWT Eclipse plug-in integrates the development mode: starting and controlling it plus displaying debug messages inside Eclipse. The development mode can be attained in any other Java IDE not just Eclipse.

UiBinder is a declarative method to create GWT-based UIs. The widgets composing an interface are declared in a template XML file and are associated with Java classes. This results in the much desired separation of UI and business logic. The GWT Eclipse plug-in contains a wizard assisting the developer with boilerplate code plus code completion, squiggles, and refactoring.

The UiBinder template can include the associated CSS widget style. That means a particular widget can be used across different applications with the exact look and feel.

Layout Panel

The introduction of a CSS-based layout panels makes it possible to create an application that looks exactly the same on any browser, a realization that was very difficult to attain before. The Mail Sample application demonstrates that. The UiBinder can be used to layout panels too.


GWT 2.0 introduces code splitting. That means that the compiled code can be split in two or more pieces. This allows the application to be started without having to wait until the whole application is loaded. Splitting is done by creating as many split points as desired by calling GWT.runAsync(). The compiler makes sure all necessary dependencies are loaded for a piece of code.

The generated JavaScript code has been further optimized in size by 3-20%.

GWT is an open source project  licensed under Apache License, v. 2.0, an SDK, Speed Tracer and the Eclipse plug-in being available for free.

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