Arun Gupta, Miles to go ...

Arun Gupta is a technology enthusiast, a passionate runner, and a community guy who works for Sun Microsystems.

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Thursday May 17, 2007

Getting Started with JRuby - Tutorial at RailsConf rails

Earlier today, I attended Charles Nutter and Thomas Enebo "Your First Day with JRuby on Rails" tutorial at Rails Conf 2007. The key message is Ruby as the programming language and Java for the platform and libraries provides the best of both worlds to developers.

JRuby is 100% pure-Java implementation of the Ruby programming language. The goal is to use the power of Ruby programming language and leverage the power of Java platform. Read a more detailed tutorial here. All Ruby scripts work with JRuby instead of the original C-based implementation. Also the goal is NOT an attempt to alter Ruby or add incompatible features. You can download JRuby implementation, unzip it and set JRUBY_HOME to the installation directory. Here is a sample JRuby code:

1. require 'java' 2. include_class 'java.lang.ArrayList' 3. include_class 'javax.swing.JFrame' 4. 5. list = ArrayList.new 6. frame = JFrame.new("Ruby SWINGS!") 7. list << frame 8. list.each { |f| f.set_size(200, 200) } 9. puts frame.title

The code above shows how Ruby and Java code can be mixed with each other. Line 1 includes Java support. Line 2 imports Java classes. Line 5 and 6 creates a new variables using a mix of Java and Ruby syntax. Line 7 and 8 uses the instance variables in Ruby syntax. Line 9 prints the title of the frame. If you run this code using JRuby interpreter then you get:

%JRUBY_HOME%/bin/jruby sample1.rb Ruby SWINGS!

Here are some of the differences (from the original C-based implementation) in JRuby:

Database support - This is required only if you want to re-use existing JDBC connection pool. Otherwise native adapter works fine and is preferred because of performance reasons.
1. Change 'database.yml' from
  
  development: adapter: mysql database: HelloWorld_development username: root password: host: localhosttodevelopment: adapter: jdbc driver: com.mysql.jdbc.Driver url: jdbc:mysql://localhost:3306/helloworld_development username: root password:
2. Include "require 'jdbc_adapter'" in 'environment.rb'.
3. Either set CLASSPATH to include JDBC driver (for example, MySQL Connector/J 5.0.5) or copy into 'work/jruby/lib' directory.
No Native extensions (at least, not until ports are available). Today, Mongrel, Hpricot are available. Database support and RMagick are in progress.
Command-line performance - JVM performs much better after the first boot so don't expect stellar command-line performance.

Here are some other points that the tutorial talked/showed:

Goldspike (nee rails-integration) that allows to WAR'up a RoR application.
Installation of GlassFish V3 as Ruby gem which will be released soon. This will allow the following interaction possible:

gem install glassfish-rails jruby script/server glassfish => Starting GlassFish => Rails application on http://localhost:8080/8080 => Rails application on http://localhost:8080/4848 => Clustering enabled => Connecting pooling enabled => Load balancing enabled => Server Ready.
JvYAML is a Java port of RbYAML.- Java YAML 1.1 parser and emitter
Deployment of Mephisto on GlassFish V3
Powerful editing, code completion, re-factoring capabilities using NetBeans IDE 6 M9. You can find more details here.

The biggest pain point from the audience was Rails deployment. With JRuby and GlassFish, you can continue deploying your apps on Mongrel. Because of JRuby, it also allows you to deploy your RoR applications on GlassFish, open-source, production-quality, Java EE 5 compatible application server.

BTW, there is supposed to be wireless connectivity through out the conference but it's very spotty :(

Technorati: glassfish rubyonrails ror netbeans railsconf

Posted by Arun Gupta in web2.0 | Comments[4]

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jMaki on Rails For Dummies

Craig announced jMaki on Rails. Here I provide detailed steps to read data from a MySQL database and display it in a jMaki-wrapped Yahoo DataTable widget.

Download NetBeans 6.0 M9 (Full version) and configured to install only "Base IDE", "Java IDE", "Web and Java EE" and "Ruby" modules. A cutting-edge build can be obtained from the hudson build.
Download and install jMaki plug-in in NetBeans update center.
1. In NetBeans 'Tools', 'Plugins', select 'Downloaded', click on 'Add Plugins ...'.
2. Select the downloaded .NBM module, click on 'Install'. This will install the jMaki plug-in and restart the IDE.
3. To verify, go to 'Tools', 'Plugins', select 'Installed'. It should show 'jMaki Ajax support' with '1.6.9.7' version number.
Create a new "Ruby on Rails Application" Project, lets say named 'jmaki_ror'.
Create a new controller by right-clicking the project, select 'Generate ...', select 'controller', specify the Name as 'jmaki' and Views as 'yahoo'.
jMaki-enable the Rails app
1. Open a command prompt and go to your application directory. Make sure you have a SVN client configured on your machine. Then invoke the following commands:
  
  script/plugin source http://jmaki-goodies.googlecode.com/svn/trunk/rails_plugins script/plugin install jmaki_core script/plugin install jmaki_yahooThe first step adds the plug-in registry to the list of registries used for searching plug-ins. The second two steps install the core and yahoo plug-ins.
2. Expand 'Views', right-click on 'layouts', select 'New', select 'Empty RHTML (Embedded Ruby) file ...'. Enter the 'File Name' as 'standard'. This will add 'standard.rhtml' in layouts sub-tree. Enter the following fragment before <body>:
  
  <head> <%= stylesheet_link_tag "jmaki-standard", :media => "all" -%> <%= javascript_include_tag "jmaki" -%> <%= jmaki_setup -%> </head>
3. Within <body>, add the following fragment:
  
  <%= @content_for_layout %>
4. In 'Controllers', 'jmaki_controller.rb', add the following fragment before 'def yahoo' line:
  
  layout "standard"
Configure the MySQL database
1. Create database using the command: 'mysqladmin -u root create jmaki_ror_development'. You need to make sure that the database name in this script is changed to match the project name.
2. Right select the NetBeans project, select 'Generate', select 'model', specify the arguments as 'grid', click 'OK'. This will generate, in NetBeans project, Database Migrations, migrate, 001_create_grids.rb.
3. Open 001_create_grids.rb, change self.up helper method such that it looks like:
  
  def self.up create_table :grids do |t| t.column :company, :string t.column :price, :float t.column :change, :float t.column :percent_change, :float t.column :last_updated, :string end end
4. Right-select NetBeans project, select 'Run Rake Target', 'db', 'migrate'. This generates the database table. Execute the following query to insert data into the table:
  
  insert into grids values (1, 'A Co', 71.72, 0.02, 0.03, 'Jan 1, 2007, 10:00am' ); insert into grids values (2, 'B Inc', 29.01, 0.42, 1.47, 'Feb 1, 2007, 10:00am' ); insert into grids values (3, 'C Group Inc', 83.81, 0.28, 0.34, 'Mar 1, 2007, 10:00am' ); insert into grids values (4, 'D Company', 52.55, 0.01, 0.02, 'Apr 1, 2007, 10:00am' );
Add jMaki-wrapped Yahoo DataTable widget
1. In NetBeans project, in 'Views', 'jmaki', 'yahoo.rhtml', drag-and-drop 'Data Table' widget from the 'Yahoo' category of jMaki palette.
  1. Until the jMaki data model for grid and data widgets is consistent between Java and JRuby, you need to replace the generated code in 'yahoo.rhtml' with the following:
    
    <%= jmaki_widget 'yahoo.dataTable', :args => { :columns => [ { :title => 'Company', :width => 200, :locked => false }, { :title => 'Price', :width => 75, :renderer => 'usMoney' }, { :title => 'Change', :width => 75, :renderer => 'change' }, { :title => '% Change', :width => 75, :renderer => 'pctChange' }, { :title => 'Last Updated', :width => 85, :renderer => 'italic' } ] }, :value => @table_data -%>
  2. '@table_data' is defined in 'jmaki_controller' in 'def yahoo' as:
    
    def yahoo @table_data = [] Grid.find_all().each do |data| @table_data << [ data.company, data.price, data.change, data.percent_change, data.last_updated] end end
That's it, run your app and view the page at 'http://localhost:3000/jmaki/yahoo'. Now jMaki-wrapped Yahoo DataTable widget is picking data from the MySQL database.

And as a next step, you can WAR'up this RoR application and deploy it on GlassFish V2 using these instructions.

Technorati: jmaki rubyonrails ror netbeans mysql glassfish

Posted by Arun Gupta in web2.0 | Comments[4]

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Database-enabled RoR WAR on GlassFish

UPDATE: Simplified steps for GlassFish V2 are available here and for V3 here.

Follow up from here.

In this post I'll show how a Ruby-on-Rails (RoR) application, talking to MySQL database, can be deployed as a WAR file on GlassFish V2. Here are the steps I followed:

Create a HelloWorld RoR app talking to MySQL database as described here.
Expand NetBeans project, expand 'Configuration' and open 'database.yml'. Change production database entry from:

production: adapter: mysql database: HelloWorld_production username: root password: host: localhost
to

production: adapter: jdbc driver: com.mysql.jdbc.Driver url: jdbc:mysql://localhost:3306/helloworld_development username: root password:

Notice, even though this is production setting we are using a "development" database.
In 'Configuration', 'environment.rb', add

require 'jdbc_adapter'

right before

Rails::Initializer.run do |config|

On some platforms, this syntax has caused problems. In that case, it may alternatively be specified (step 9) as:
```
if RUBY_PLATFORM =~ /java/
       require 'rubygems'
       RAILS_CONNECTION_ADAPTERS = %w(jdbc)
end
```
Recreate the WAR file by invoking the command 'rake war:standalone:create' from your application directory.
Drop this WAR file in "domains/domain1/autodeploy" directory of your GlassFish instance and you are done!