Imagine for a moment that you're developing a Confluence plugin. Usually each change to your code requires at a minimum that you:

• uninstall the plugin
• run a maven build (which also reinstalls the plugin)
• if you're using a debugger probably struggle a bit to keep the instruction pointer on track

This is already an extremely efficient process for server development by any measure, but still takes a few manual steps and likely at least 20 to 30 seconds. That's not long, but after a few iterations is just enough time to where you might decide to glance at Digg, the BBC or see if the Chevy Volt is still on schedule and get distracted.

Now imagine there is virtually nothing to do and no delay for your Java changes to be picked up - approximately 1 second.

This is JavaRebel.

There is thorough information on the JavaRebel site in terms of the advantages and benefits it affords so I'll just briefly mention my personal experience.

The one thing I've always liked least about server side development are the delays to compile, redeploy and sometimes even minutes to restart a server. What JavaRebel has accomplished is really a Holy Grail of sorts in my mind.

I tried using JavaRebel for plugin devel upon its release in 2007. However at the time I could not get it to work with Confluence's plugin class loader. Last week I decided to give it another go and with help from their very responsive support and leveraging a new 'JavaRebel plugin framework' we now have it working with the Confluence plugin devel cycle.

Here is a demo video I made showing it used with a Confluence plugin
Here are the JavaRebel installation instructions specific to Confluence.

There are more polished videos of JavaRebel in use here.

One last question might be, "Is it worth the price?" (currently $49 or $149 or ....) I believe JavaRebel easily pays for itself in a couple hours of active coding in increased productivity not to mention a sense of empowerment and accomplishment when you start to fly through tasks in minutes that used to take hours. Personally I think Java development just got a lot more fun.

One last thing. I've not yet tried it with JIRA plugin development but the benefits will be even much more vast as JIRA does not as of yet support dynamic loading for plugins. Actually because of JavaRebel I plan to become much more active in JIRA development.