GlassFish gem as well as GlassFish v3 supports Rack. Rack provides an interface to plugin a Ruby web framework with a web sever. Similar to Python WSGI. This means that any ruby based framework that can talk Rack can be simply deployed on GlassFish.

Here is how you can do it on GlassFish gem:

Insall JRuby

Install JRuby from here. Setup JRUBY_HOME to the install location and add JRUBY_HOME/bin to your PATH.

Install GlassFish gem

$ gem install glassfish

Now, lets write a trivial app and save it in file: myapp.rb

class MyApp
 def self.Run
 "Hello World"
 end
end

Write a rack-up script and save it in myframework.ru

require 'rubygems'
gem 'rack'
require 'rack/handler/grizzly'
require 'myapp'

app = proc do |env|
 resp = MyApp.Run
 [
 200, # Status code
 { # Response headers
 'Content-Type' => 'text/html',
 'Content-Length' => resp.length,
 },
 [resp] # Response body
 ]
end

That is pretty much your sample Ruby application and the Rack-up script to run on GlassFish. Above require 'rack/handler/grizzly' makes Grizzly handler available to Rack.

To run it, simply run glassfish in side the directory where myapp.rb and myframework.ru are placed.

% glassfish
Starting GlassFish server at: 192.168.1.103:3000 in development environment...
Writing log messages to: /Users/vivek/dev/foo/log/development.log.
Press Ctrl+C to stop.

Now access, http://localhost:3000 in your browser to access your app.

If you are running GlassFish v3 server and want to deploy this app, you would simply use the same asadmin command from inside the application directory:

$ asadmin deploy .

GlassFish gem as well as GlassFish v3 server can auto-detect Rails, Merb and Sinatra applications. You can use the above mentioned technique to plugin other frameworks. For reference also see Jacob's blog where he explains how Sintra application is plugged in to GlassFish.