WAR-based packaging and dispatching of Rails application on Java Application Servers is going through third iteration based what is used for packaging and dispatching:

• Goldspike + RailsServlet: The first iteration was WAR-packaging of Rails app as defined by Goldspike plugin (nee Rails-integration) and using RailsServlet (part of Goldspike) for dispatching.
• Warbler + RailsServlet: The second iteration (slightly short lived) overcame the shortcomings of Goldspike (packaging with sane defaults, fast, light-weight, and flexible configuration) by using Warbler for packaging. It decoupled packaging and dispatching by doing only packaging and allowing for pluggable dispatching mechanism. RailsServlet continues to be the default Servlet binding mechanism. This is the version currently supported by GlassFish v2 Update Center.
• Warbler + Rack:  Nick released JRuby-Rack (JRuby version of Rack, also see Introducing Rack and Docs) last week. And so the third iteration is using Warbler packaging and Rack-based dispatching. JRuby-Rack provides a more seamless connection between the Servlet environment and Rack.

The JRuby-Rack wiki says " JRuby-Rack is a lightweight adapter for the Java servlet environment that allows any Rack-based application to run unmodified in a Java servlet container. JRuby-Rack supports Rails, Merb, as well as any Rack-compatible Ruby web framework.".

This means that, other than Rails, conceptually Merb applications (which also use Rack for deployment) can now also be deployed on GlassFish. This blog entry explains how to deploy a simple Rack-based Rails application.

1. Install Rails and JRuby-Rack (as part of Warbler) as:
   
   

   ~/testbed/jruby-1.1.1 >bin/jruby -S gem install rails warbler --no-ri --no-rdoc JRuby limited openssl loaded. gem install jruby-openssl for full support. http://wiki.jruby.org/wiki/JRuby_Builtin_OpenSSL Updating metadata for 289 gems from http://gems.rubyforge.org/ .............................................................................................................................. .............................................................................................................................. ..................................... complete Successfully installed activesupport-2.0.2 Successfully installed activerecord-2.0.2 Successfully installed actionpack-2.0.2 Successfully installed actionmailer-2.0.2 Successfully installed activeresource-2.0.2 Successfully installed rails-2.0.2 Successfully installed warbler-0.9.9 7 gems installed

2. Create a template Rails app as:
   
   

   ~/testbed/jruby-1.1.1/samples/rails >../../bin/jruby -S rails hello -d mysql       create        create  app/controllers       create  app/helpers       create  app/models       create  app/views/layouts       create  config/environments       . . .       create  doc/README_FOR_APP       create  log/server.log       create  log/production.log       create  log/development.log       create  log/test.log

3. Disable database access from the application by uncommenting line 21 (remove "#" at the beginning) from "config/environment.rb" as:
   
   

   config.frameworks -= [ :active_record, :active_resource, :action_mailer ]

4. Create a WAR file as:
   
   

   ~/testbed/jruby-1.1.1/samples/rails/hello >../../../bin/jruby -S warble JRuby limited openssl loaded. gem install jruby-openssl for full support. http://wiki.jruby.org/wiki/JRuby_Builtin_OpenSSL jar cf hello.war -C tmp/war .


A new file "hello.war" is generated in the current directory.
5. The generated WAR file can be easily deployed on GlassFish.
   1. Download and Install GlassFish v2 UR2 from here.
   2. Start GlassFish Application Server as:
      
      

      ~/testbed/glassfish/v2ur2/glassfish >bin/asadmin start-domain --verbose Starting Domain domain1, please wait. May 13, 2008 11:23:44 AM com.sun.enterprise.admin.servermgmt.launch.ASLauncher buildCommand INFO: /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home/bin/java . . . [#|2008-05-13T11:34:13.252-0700|INFO|sun-appserver9.1|javax.enterprise.system.container.web|_ThreadID=10;_ThreadName=main;4848;|WEB0712: Starting Sun-Java-System/Application-Server HTTP/1.1 on 4848|#] [#|2008-05-13T11:34:13.691-0700|INFO|sun-appserver9.1|javax.enterprise.system.core.selfmanagement|_ThreadID=10;_ThreadName=main;|SMGT0007: Self Management Rules service is enabled|#] [#|2008-05-13T11:34:13.718-0700|INFO|sun-appserver9.1|javax.enterprise.system.core|_ThreadID=10;_ThreadName=main;|Application server startup complete.|#]

   3. Deploy the WAR on GlassFish as:
      
      

      ~/testbed/jruby-1.1.1/samples/rails/hello >~/testbed/glassfish/v2ur2/glassfish/bin/asadmin deploy hello.war Command deploy executed successfully.

      
      The output in the GlassFish console looks like:
      
      

      [#|2008-05-13T11:34:23.330-0700|INFO|sun-appserver9.1|javax.enterprise.system.tools.admin|_ThreadID=14;_ThreadName=httpWorkerThread-4848-0;/private/tmp/s1astempdomain1server1547440193/hello.war;|ADM1006:Uploading the file to:[/private/tmp/s1astempdomain1server1547440193/hello.war]|#] [#|2008-05-13T11:34:26.019-0700|INFO|sun-appserver9.1|javax.enterprise.system.tools.deployment|_ThreadID=15;_ThreadName=Thread-30;|deployed with moduleid = hello|#] [#|2008-05-13T11:34:30.626-0700|INFO|sun-appserver9.1|javax.enterprise.system.container.web|_ThreadID=16;_ThreadName=httpWorkerThread-4848-1;|PWC1412: WebModule[/hello] ServletContext.log():Info: using runtime pool timeout of 30 seconds|#] [#|2008-05-13T11:34:30.626-0700|INFO|sun-appserver9.1|javax.enterprise.system.container.web|_ThreadID=16;_ThreadName=httpWorkerThread-4848-1;|PWC1412: WebModule[/hello] ServletContext.log():Warning: no initial runtimes specified.|#] [#|2008-05-13T11:34:30.627-0700|INFO|sun-appserver9.1|javax.enterprise.system.container.web|_ThreadID=16;_ThreadName=httpWorkerThread-4848-1;|PWC1412: WebModule[/hello] ServletContext.log():Warning: no max runtimes specified.|#]

   4. The default Rails page is now visible at "http://localhost:8080/hello" as shown below:
      
      
6. Add some functionality to the application to show Servlet and Rack integration
   1. Add a Controller and View as
      
      

      ~/testbed/jruby-1.1.1/samples/rails/hello >../../../bin/jruby script/generate controller home index JRuby limited openssl loaded. gem install jruby-openssl for full support. http://wiki.jruby.org/wiki/JRuby_Builtin_OpenSSL       exists  app/controllers/       exists  app/helpers/       create  app/views/home       exists  test/functional/       create  app/controllers/home_controller.rb       create  test/functional/home_controller_test.rb       create  app/helpers/home_helper.rb       create  app/views/home/index.html.erb

   2. Change the "index" helper method in "app/controllers/home_controller.rb" as:
      
      

      def index         @greeting = "Hello from Rack!!"         # access Servlet Context         @server_info = $servlet_context.get_server_info         # alternative way to get Servlet Context         #@server_info2 = request.env['java.servlet_context'].get_server_info         # access Servlet Request         @method = request.env['java.servlet_request'].get_method         @request_uri = request.env['java.servlet_request'].get_request_uri         @protocol = request.env['java.servlet_request'].get_protocol         @port = request.env['java.servlet_request'].get_server_port end

   3. Add the following fragment as the last line in "app/views/home/index.html.erb":
      
      

      <%= @greeting %><br><br> Hosted on "<%= @server_info %>" on port "<%= @port %>"<br> <%= @method %> <%= @request_uri %> <%= @protocol %>

7. Re-create and deploy the WAR file
   1. Re-create the WAR file as explained in step 4.
   2. Re-deploy the WAR file as explained in step 5.3.
   3. Now "http://localhost:8080/hello/home/index" shows the output as:
      
      

The magic fragment in "tmp/war/WEB-INF/web.xml" is:

<filter>     <filter-name>RackFilter</filter-name>     <filter-class>org.jruby.rack.RackFilter</filter-class>   </filter>   <filter-mapping>     <filter-name>RackFilter</filter-name>     <url-pattern>/*</url-pattern>   </filter-mapping>   <listener>     <listener-class>org.jruby.rack.rails.RailsServletContextListener</listener-class>   </listener>

And also "WEB-INF/lib/jruby-rack-0.9.jar" is bundled in the WAR.
Let us know if you try Rack-based deployment of Merb applications on GlassFish.