Rails and Java EE integration - Servlet co-bundled and invoked from Rails

One of the several advantages of deploying Rails applications on GlassFish is - co-hosting Rails and Java EE applications in the same container. The screencast #web9 shows how Rails applications can be easily deployed on GlassFish.

This blog takes the JRuby-on-Rails (jRoR) and Java EE integration to the next level. It show how a Java EE Servlet can be co-bundled within a jRoR application. And then it shows how such a servlet can be easily invoked from a Rails view. It uses WAR-based mode for deploying jRoR applications on GlassFish.

Here are the detailed steps:

1. In an existing JRuby 1.1 RC3 installation (enabled with Rails), install the required gems:
   
   

   ~/testbed/jruby-1.1RC3 >bin/jruby -S gem install activerecord-jdbc-adapter    JRuby limited openssl loaded. gem install jruby-openssl for full support. http://wiki.jruby.org/wiki/JRuby_Builtin_OpenSSL Successfully installed activerecord-jdbc-adapter-0.8 1 gem installed Installing ri documentation for activerecord-jdbc-adapter-0.8... Installing RDoc documentation for activerecord-jdbc-adapter-0.8...

2. Create a Rails app as:
   
   

   ~/testbed/jruby-1.1RC3/samples/rails >../../bin/jruby -S rails railsee1       create        create  app/controllers       create  app/helpers       create  app/models       create  app/views/layouts       create  config/environments       create  config/initializers       create  db       create  doc       create  lib       create  lib/tasks       create  log       create  public/images       create  public/javascripts       create  public/stylesheets       create  script/performance       create  script/process       create  test/fixtures       create  test/functional       create  test/integration       create  test/mocks/development       create  test/mocks/test       create  test/unit       create  vendor       create  vendor/plugins       create  tmp/sessions       create  tmp/sockets       create  tmp/cache       create  tmp/pids       create  Rakefile       create  README       create  app/controllers/application.rb       create  app/helpers/application_helper.rb       create  test/test_helper.rb       create  config/database.yml       create  config/routes.rb       create  public/.htaccess       create  config/initializers/inflections.rb       create  config/initializers/mime_types.rb       create  config/boot.rb       create  config/environment.rb       create  config/environments/production.rb       create  config/environments/development.rb       create  config/environments/test.rb       create  script/about       create  script/console       create  script/destroy       create  script/generate       create  script/performance/benchmarker       create  script/performance/profiler       create  script/performance/request       create  script/process/reaper       create  script/process/spawner       create  script/process/inspector       create  script/runner       create  script/server       create  script/plugin       create  public/dispatch.rb       create  public/dispatch.cgi       create  public/dispatch.fcgi       create  public/404.html       create  public/422.html       create  public/500.html       create  public/index.html       create  public/favicon.ico       create  public/robots.txt       create  public/images/rails.png       create  public/javascripts/prototype.js       create  public/javascripts/effects.js       create  public/javascripts/dragdrop.js       create  public/javascripts/controls.js       create  public/javascripts/application.js       create  doc/README_FOR_APP       create  log/server.log       create  log/production.log       create  log/development.log       create  log/test.log

3. Install Goldspike plugin in the application as:
   
   

   ~/testbed/jruby-1.1RC3/samples/rails/railsee1 >../../../bin/jruby script/plugin install svn://rubyforge.org/var/svn/jruby-extras/trunk/rails-integration/plugins/goldspike A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/test A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/test/war_config_test_config.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/test/test_java_library.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/test/test_maven_library.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/test/test_create_war.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/Rakefile A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/init.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/tasks A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/tasks/war.rake A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/lib A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/lib/util.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/lib/war_config.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/lib/run.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/lib/java_library.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/lib/packer.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/lib/create_war.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/install.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/generators A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/generators/goldspike A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/generators/goldspike/goldspike_generator.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/generators/goldspike/templates A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/generators/goldspike/templates/web.xml.erb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/generators/goldspike/templates/war.rb A    /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1/vendor/plugins/goldspike/README Exported revision 960.       exists  config       create  config/war.rb       create  WEB-INF       create  WEB-INF/web.xml.erb

   
   Optionally Warbler may be used for packaging and Goldspike for dispatching.
4. Create a Java library with Servlet code
1. Using NetBeans IDE, create a project of type "Java Class Library" and specify the name "HelloServlet".
2. Right-click on the project, select "New" and "Servlet...". Enter the class name as "HelloServlet" and package as "server" as shown below:
   
   
3. Right-click on the project, select Properties and in "Libraries", "Compile Tab Libraries" add "javaee.jar" from GlassFish v2 UR1 "lib" directory.
4. Change the "try" block in "processRequest" method to following:
   
   

   String name = request.getParameter("name"); if (name == null || name.equals(""))     name = "Duke";             out.println("<h1>Servlet HelloServlet at " + request.getContextPath () + " says Hello " + name + "!</h1>");

5. Right-click on the project and select "Clean and Build".
5. Configure Rails app for Servlet
1. In your Rails application directory, add the following fragments to "WEB-INF/web.xml.erb":
   
   

   <servlet>                 <servlet-name>hello</servlet-name>                 <servlet-class>server.HelloServlet</servlet-class> </servlet>

   
   

   <servlet-mapping>                 <servlet-name>hello</servlet-name>                 <url-pattern>/hello</url-pattern> </servlet-mapping>

2. Create "WEB-INF/lib" directory and copy "HelloServlet.jar" from the "dist" directory of NetBeans project here.
6. Create & Deploy the WAR
1. Create a WAR file as:
   
   

   ~/testbed/jruby-1.1RC3/samples/rails/railsee1 >../../../bin/jruby -S rake war:standalone:create (in /Users/arungupta/testbed/jruby-1.1RC3/samples/rails/railsee1) info: Assembling web application info: Packing needed Java libraries ... info:   adding Java library jruby-complete-1.1RC3 info:   adding Java library goldspike-1.6 info:   adding Java library activation-1.1 info:   adding Java library commons-pool-1.3 info:   adding Java library bcprov-jdk14-124 info: Packing needed Ruby gems ... info:   adding Ruby gem rails version 2.0.2 info:   adding Ruby gem rake version 0.8.1 info:   adding Ruby gem activesupport version 2.0.2 info:   adding Ruby gem activerecord version 2.0.2 info:   adding Ruby gem actionpack version 2.0.2 info:   adding Ruby gem actionmailer version 2.0.2 info:   adding Ruby gem activeresource version 2.0.2 info:   adding Ruby gem activerecord-jdbc-adapter version 0.8 info: Packing needed files ... info: Creating web archive

2. Deploy the WAR to GlassFish v2 UR1 as:
   
   

   ~/testbed/jruby-1.1RC3/samples/rails/railsee1 >~/testbed/glassfish/v2ur1/glassfish/bin/asadmin deploy railsee1.war Command deploy executed successfully.

7. The bundled Servlet is now accessible at "http://localhost:8080/railsee1/hello". The default browser output looks like:
   
   
   
   And passing a parameter to the URL as "http://localhost:8080/railsee1/hello?name=Arun" shows the output as:
   
   
With this, your Java EE Servlet is now bundled with your Rails application deployed on GlassFish v2 UR1.

Now, lets add Controller and View to Rails application and invoke this servlet from there to show complete integration with Rails.

8. Create a new Controller and View as
   
   

   ~/testbed/jruby-1.1RC3/samples/rails/railsee1 >../../../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

9. Change the generated controller in "app/controllers/home_controller.rb" to:
   
   

   class HomeController < ApplicationController include Java   def index         url = java.net.URL.new("http://localhost:8080/railsee1/hello");         conn = url.open_connection;         reader = java.io.BufferedReader.new(java.io.InputStreamReader.new(conn.get_input_stream));         @servlet_output = "";         input_line = reader.read_line;         while input_line != nil                 @servlet_output << input_line;                 input_line = reader.read_line;         end         reader.close;   end end

10. Change the generated view in "app/views/home/index.rhtml.erb" to:
    
    

    <h1>Home#index</h1> <p>Find me in app/views/home/index.html.erb</p> <%= @servlet_output %>

11. Re-create & re-deploy the WAR as describd in bullet # 6 above. And now "http://localhost:8080/railsee1/home/index" shows the output as shown:
    
    

This shows how a Java EE 5 Servlet can be easily invoked from a Rails application deployed on GlassFish. JRuby-on-Rails and GlassFish allows you to leverage business knowledge that exists in Java EE applications very easily and still providing Rails agility.


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