Today HTML 5 is one of the most sophisticated and popular UI technology available. Unfortunately writing business code using Javascript is a mess. If you are used to Java’s type safety, the modularity of OSGi and all that dozens of third party libraries, you know that plain Javascript is a huge step backwards. The Java Virtual Machine and HTML complement each other for many years in web based applications. So why not combine both technologies to create rich desktop applications? A platform independent user interface on top of a platform independent programming language – a perfect match!

I was very excited when I heard about the HTML 5 support in JavaFX. However the ‘Webview’ rendering is very bad and not comparable to most recent web browsers. Fortunately the browser support in SWT was improved with Eclipse Luna and embedding XULRunner 24.x is now possible.

XULRunner is the primary HTML rendering engine used by Firefox and is available on all major operating systems. The WebGL support in XULRunner is great, audio and video playback are implemented. Also the rendering result on different platforms is almost identical so you don’t have to fight with all that different browser quirks as usual in web development.

The demo below shows an SWT based application with embedded XULRunner that renders a simple WebGL scene using three.js.

The SWT browser API supports calling Java from Javascript and vice versa. I added the ‘Take Screenshot’ and ‘Add Image’ button just to demonstrate the interaction ability. The screen capture itself is based on the solution I posted a while ago . The source code for the demo is available here.

After you can not rely on a proper XULRunner installed on your user’s target machine, bundle your application together with the appropriate XULRunner version. For OSGi based applications this is really straightforward and an exemplary implementation can be found here (Sorry I couldn’t integrate the OSX version yet).

The org.mozilla.xulrunner bundle is the platform independent host bundle with helper classes to instantiate XULRunner based browsers. The XULRunner binaries are provided by platform specific fragment bundles, one fragment for each operating system characteristic.

XULRunner is not supported for GTK3 so under Linux you have to use a start script to run your application:

 
#!/bin/bash
export SWT_GTK3=0
./yourApp

At the moment I’m playing with different approaches to combine Java and HTML. Single page apps with Java calls using AngularJS and Bootstrap, server centric solution using Vaadin and RAP. So far I have absolutely no idea what works best but I let you know in the near future on this blog.