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Rails and Java EE integration - Warbler instead of Goldspike


Part 1 of this tri-series blog explained how a Java EE Servlet and Rails application can be packaged together as WAR file using Goldspike plugin and deployed on GlassFish v2 UR1. There are few issues with Goldspike as explained here. A better and recommended option is to use Warbler for packaging which provides a minimal, flexible and Ruby-like way to create WAR. Warbler really cleans up the packagingof WAR, for example excluding .svn directories, tests and migrations - really nice. For now, it uses RailsServlet for dispatching but even that is pluggable.

This blog, Part 2, will explain how to generate a WAR file using Warbler. Rails powered by GlassFish provides all the details on why GlassFish provides an industry-grade and functionally-rich Application Server.

Now detailed steps:
  1. In an existing JRuby 1.1 installation (enabled with Rails), install Warbler gem:

    ~/testbed/jruby-1.1 >bin/jruby -S gem install warbler
    JRuby limited openssl loaded. gem install jruby-openssl for full support.
    Updating metadata for 35 gems from http://gems.rubyforge.org
    Successfully installed warbler-0.9.4
    1 gem installed
    Installing ri documentation for warbler-0.9.4...
    Installing RDoc documentation for warbler-0.9.4...
  2. Create a Rails app "railsee2" as:

    ~/testbed/jruby-1.1/samples/rails >../../bin/jruby -S rails railsee2
          create  app/controllers
          create  app/helpers
          create  app/models
          . . .
          create  log/production.log
          create  log/development.log
          create  log/test.log

    In order to keep it simple, this application will not be using any database so uncomment the following line from "config/environment.rb"(by removing "#" from beginning of the line):

    config.frameworks -= [ :active_record, :active_resource, :action_mailer ]
  3. Create a new file "web.xml" in "config" directory and use the following contents:

    <!DOCTYPE web-app PUBLIC
      "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"

    This "web.xml" is used by Warbler when packaging the WAR file.
  4. Create and Copy Servlet
    1. Create a Java library with Servlet code as explained in bullet #5 here.
    2. Copy "HelloServlet.jar" from "dist" directory of NetBeans project to "lib" directory of Rails application.
  5. Create and deploy the WAR
    1. Create a WAR file as:

      ~/testbed/jruby-1.1/samples/rails/railsee2 >~/testbed/jruby-1.1/bin/jruby -S warble
      JRuby limited openssl loaded. gem install jruby-openssl for full support.
      jar cf railsee2.war -C tmp/war .
    2. Deploy the WAR to GlassFish v2 UR1 as:

      ~/testbed/jruby-1.1/samples/rails/railsee2 >~/testbed/glassfish/v2ur1/glassfish/bin/asadmin deploy railsee2.war
      Command deploy executed successfully.
  6. The bundled Servlet is now accessible at "http://localhost:8080/railsee2/hello". The default browser output looks like:

    And passing a parameter to the URL as "http://localhost:8080/railsee2/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.
  1. Create a new Controller and View as

    ~/testbed/jruby-1.1/samples/rails/railsee2 >../../../bin/jruby script/generate controller home index
    JRuby limited openssl loaded. gem install jruby-openssl for full support.
          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 generated controller in "app/controllers/home_controller.rb" to:

    class HomeController < ApplicationController

    include Java

      def index
            url = java.net.URL.new("http://localhost:8080/railsee2/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;
  3. Change the generated view in "app/views/home/index.rhtml.erb" to:

    <p>Find me in app/views/home/index.html.erb</p>

    <%= @servlet_output %>
  4. Re-create the WAR as describd in bullet # 5 above. And now "http://localhost:8080/railsee2/home/index" shows the output as shown:

This blog explained how a Java EE 5 Servlet and Rails application can be packaged Warbler and deployed on GlassFish. Warbler docs provide detail about usage, configuration, web.xml and other details.

The next blog in this tri-series blog will explain how such an application can be deployed on GlassFish v3. And the cool thing there is that you don't need Goldspike, Warbler or any other additional plugins - total native deployment, stay tuned!


Published at DZone with permission of Arun Gupta, DZone MVB. See the original article here.

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