Yesterday's latest talk was about zero turnaround development in Java. I mainly attended the session because I really, really hate waiting for the tedious deploy cycle after changing some code. It's one of the main reasons I believe Grails works so efficient compared to most other web frameworks (even while Grails doesn't do real hot swapping code). The session was extremely well structured. First the turnaround problem was explained including the technical difficulties. More interesting where the reasons why the turnaround problem is so painful. Besides the actual time you spend waiting each week, it also completely disrupts your 'flow'. Costing much more time to get back into your work. The fact that quality of work is probably also hurt a lot was not even covered, but I'm sure this will even be a big factor too. Seams to be another good reason to go for a more lightweight development approach... 

Next some basic solutions where covered (which can be used with standard tools), which can make live a lot better but are still not a full solution. At last JavaRebel was covered. JavaRebel is a commercial tool, but is very reasonable priced (it's actually really cheap). JavaRebel install's an agent into the VM, enabling to hotswap almost all type of code changes without any restart or re-initialization required. It's truly amazing. It's even more amazing that you don't have to do anything to get this behavior, other than enabling the agent. It event supports deeper support for a few frameworks, including Spring, to hot swap configuration files.

After showing JavaRebel a short demo was shown about a new tool of the company. It's sort of a server runtime that enables you to hot upgrade and downgrade applications without ever going down. This was even proofed during the session by upgrading a chat application that was running at that very moment in the conference room. Not a second of downtime. The only thing I was thinking about after the session was: I want this. I'm going to try out JavaRebel and probably going to get a personal license.