Packaged deployment. We now support deployment as WAR/EAR with exactly the same feel that exploded development has. All the classes and resources will be reloaded on the fly as soon as you hit Save. All you have to do is create a rebel.xml configuration file that will tell JavaRebel where to find the updated classes and resources. On top of that we now provide a Maven plugin that will do this configuration for you!
Very low performance overhead. The performance of the application with JavaRebel enabled is now pretty much the same as without JavaRebel.
Better startup time. Application or server startup time should be much nearer to the usual one, though there still is more work to be done when starting with JavaRebel, so some slowdown is expected.
Spring, Guice, Stripes, Tapestry 4 and Struts2 reload out of the box. Plugins for those frameworks are now included with JavaRebel and allow configuration to be changed instantly, just as classes.
Better compatibility. We’ve done a whole lot of work on making JavaRebel more compatible with Java projects in the wild. This involved making sure that Reflection API behaves 100% predictably, extensive test suites in many environments and lot of integration work. In particular AspectJ load-time-weaving, IBM WebSphere and Groovy are now fully supported.
Jevgeni Kabanov is the founder and CEO of ZeroTurnaround (www.zeroturnaround.com), a development tools company that focuses on productivity. Jevgeni has been speaking at international conferences for over 5 years, including JavaPolis/Devoxx, JavaZone, JAOO, QCon, TSSJS, JFokus and so on. He also has an active research interest in programming languages, types and virtual machines, publishing several papers on topics ranging from category theoretical notions to typesafe Java DSLs. You can follow Jevgeni on Twitter as @ekabanov.