Motivated by the talk Do you really get class loaders? from Jevgeni Kabanov @devoxx in Antwerpen, I’ve downloaded the demo version of JRebel this evening.
JRebel promises faster and much more pleasant Java application development because of mapping the project workspace directly to a running application. That means that no more long deployment procedures (mvn clean install…) are necessary for simple code changes. And it should also work with my current technology stack… Sounds pretty cool, doesn’t it?

So I downloaded the demo version (as a devoxx visitor, I also got a free personal license 😉 ) and installed it. Yes, you read correct, it’s an installer that leads you step by step through the configuration. Probably 20min later, my SpringSource Tools Suite is ready for the first test; I start the server (Tomcat 6.0) and change a jsp (not big business). Oh; it works. Then, a java class, a .properties file, and finally the applicationContext.xml. Just save the file and reload the webpage and it works… feels like developing in the good old php times.

I’ve tried this with a small Spring application. The deployment only takes a couple of seconds, but even then JRebel really gives you a benefit, it’s just more fun to develop 😉
There are also limitations, replacing superclasses and adding/removing implemented interfaces doesn’t work, for that a deployment is still necessary.
Really interesting will it be to try it out with larger applications like WCMS systems for which the deployment takes much longer. More about this may be in the next post 😉