Apache Wicket 6.0 gets released today, with a number of enhancements that make it one of the most compelling choices for web development in Java. With JQuery integration provided out of the box, improvements throughout the client side API, and an experimental WebSocket implementation, this should be a popular upgrade for Wicket users.

"This release delivers a reinvigorated implementation of our client side API that enables developers to integrate rich JavaScript libraries and components with minimal effort. We have updated and broadened the capability and flexibility of many existing features throughout the framework," said Martijn Dashorst, Vice President of Apache Wicket.

Here's a quick rundown on what's included.

JQuery Now Available Out-Of-The-Box

Wicket's custom AJAX JavaScript library has been re-implemented using JQuery, so it will be easier to integrate JQuery plugins into Wicket applications. Of course, it's still possible to use your own version of JQuery if required.

AJAX Attributes

With the new and improved AJAX implementation, you can alter any aspect of an AJAX request through AjaxRequestAttributes. For example you can specify that the request should be executed using POST instead of GET, or that the AJAX request should be multi-part, etc. See the migration guide or the JavaDoc of AjaxRequestAttributes for all possible options.

Browser event registration replaces inline events

Wicket now uses JavaScript event registration instead of inline attributes for AJAX components. This enables multiple event listeners to be attached to a markup tag, cleans up the rendered markup considerably and reduces the amount of generated markup.

IDataProvider now uses long instead of int

The IDataProvider<T> interface and implementations now use long instead of int for index and size parameters to better line up with the Java Persistence API and other persistency frameworks. Big data is now possible with Wicket!

${label} replaces ${input} in feedback messages

Previous Wicket versions used the input that was provided by users in error messages when validations failed. This led to error messages like "1234a is not a valid number". In Wicket 6 the feedback messages use the label of the invalid form component instead. You can set the label by calling setLabel() on the form component. If no label is provided, Wicket defaults to displaying the component identifier. This changes the error message to "Phonenumber is not a valid number".

Resources can declare dependencies - It is now much easier to create resource contributions with dependencies, for example a JQuery plugin can declare a dependency on JQuery and other resources such as embedded style sheets. Users of such resources don’t have to provide these dependencies themselves, and the dependencies are linked in the appropriate order.
Packaged resources will use minimized version automatically - When a minimized JavaScript resource is available (filename.min.js – add the .min part to the filename before the extension), Wicket will automatically use the minimized version when running in deployment mode, while using the non-minimized version for development mode.

OSGi compatible packaging

Wicket's packaging has been made compatible with OSGi bundles by moving some classes to different packages. The full list can be found in our migration guide. This makes it much easier to deploy Wicket applications in an OSGi environment

Experimental websocket implementations

This release also includes two experimental websocket implementations: one using Atmosphere as a bridge for browsers and containers that don’t support websockets natively and one for containers and browsers that have native websocket support.

Java 6 As Minimum Required Version

If your existing Wicket application has been using an earlier Java version, and you want to take advantage of Wicket 6.0 features, you'll need to upgrade your Java runtime too.

The headline features include

• Out-of-the box JQuery integration
• Complete control over AJAX requests
• Improved event registration in browsers
• Support for large datasets in components
• Dependency management for client side JavaScript libraries
• Experimental support for WebSockets

The complete set of changes is available in the migration guide at http://s.apache.org/wicket-6.0-migration