Google App Engine with JRuby - can someone provide an overview of appengine-jruby, warble etc?

I'm getting myself confused as to how to get a JRuby app cranking on App Engine.

I know that you can get started using the appengine-jruby "gem" (Note: I'm a Java programmer, so this is all completely new to me). I've also seen some talk about Warbler, and am getting the impression that I could probably use Warbler somehow with App Engine.

Why I'm not diving into appengine-jruby straight away is that I'm seeing some strange things like the following:

This project uses its own customised version of jruby that is packaged ('frozen' in ruby speak) with the other gems.

Some things I've seen about Warbler is also making me curious, e.g:

Warbler provides a sane set of out-of-the box defaults that should allow most Rails applications without external gem dependencies (aside from Rails itself) to assemble and just work.

I'm just sort of wondering what are the different ways of getting a 开发者_如何学运维JRuby app going on App Engine. Is there someone that could explain the big picture?

For now I think I'll just get started, and use the appengine-jruby gem.

Thanks heaps :)

JRuby on App Engine requires a bunch of special gems. A great Getting Started Guide is HERE.

I would also recommend following John Woodell on Twitter. He's one of Googles few Ruby programmers, and speaks at a lot of conferences about running JRuby on GAE.

http://blog.nicksieger.com/files/Sieger-RailsDeployment-J12008.pdf might help http://jruby-appengine.blogspot.com/2010/09/google-app-engine-0017-gems-released.html too

Install the gem, then create the sample application on the getting started pages. Until everything gets updated you have to tweak a few things to make it work:

1. rubygems needs to be no later a version than 1.3.5. If it is newer, uninstall rubygem-update.

2. in the Gemfile you need to force jruby-rack to version 1.0.5 like this: gem "jruby-rack", "1.0.5" (one user reported needing to force to 1.0.4)

Right now the framework is desperately needing an upgrade to fix a few issues like these, but as I understand, it needs to wait for bundler to be upgraded to make the jump.

Don't be afraid to send questions to the mailing list. There are lots of people willing to help.