JRuby and Hibernate

The beautiful thing about Rails on JRuby is that you have access to Java. Perhaps you have existing code you'd like to reuse or maybe there's some functionality in a Java library you'd like to use. Whatever the reason, it's good to know how to do it.

So today I created a new Rails app to demonstrate how to use Rails' controllers and views with some model classes from one of my earlier Java projects. My old app used the typical HibernateUtil singleton (section 1.2.5 of the Hibernate docs). I also liked the ActiveRecord pattern so my Java domain classes had some handy "find" methods. So in order to make this work in a Rails app, I installed the goldspike plugin:

script/plugin install http://jruby-extras.rubyforge.org/svn/trunk/rails-integration/plugins/goldspike

and then ran the rake task war:standalone:create

I copied the classes and lib directories from my old apps' WEB-INF directory to the WEB-INF directory in my Rails app and then generated a controller and modified it to look like this:

require 'java'
import 'com.example.domain.Person'
import 'com.example.util.HibernateUtil'

class PersonController < ApplicationController
  def list
    with_transaction do
      @people = Person.find_all.to_a
      @people.sort!{|p1, p2| p1.name.downcase <=> p2.name.downcase}
    end
  end
  
  def with_transaction
    begin
      tx = HibernateUtil.session_factory.current_session.beginTransaction
      yield
      tx.commit
      HibernateUtil.session_factory.current_session.close
    rescue
      tx.rollback
    end
  end
end

Finally, I added a list.rhtml template for the "list" action and voila! I have a Rails-ish app that uses Hibernate instead of ActiveRecord.

Ruby Cocoa

RubyCocoa and the Scripting Bridge are two software development technologies bundled with Leopard. The app presented here demonstrate how to create a native Mac interface written in Ruby that communicates with iTunes via Applescript. It does nothing more than display the iTunes version number.

1. Create a "Ruby-Cocoa Application" from the "New Project" dialog in XCode
2. Add a "Ruby NSObject subclass" to the project called "ITunesController"
3. Add an ib_outlet for a text field and an ib_action called "show_version" to the ITunesController ruby class.
4. Generate an Objective-C header file that scripting bridge can use to communicate with iTunes. Use the two terminal command, sdef and sdp, within your project folder like this: "sdef /Applications/iTunes.app | sdp -fh --basename iTunes"
5. Add the header file to your project.
6. Add "ScriptingBridge.framework" to your project.
7. Open "MainMenu.nib" in Interface Builder and add a button and a label to the Window. Also instantiate an NSObject subclass.
8. Set the NSObject's class to "ITunesController". (You may need to select the "Read Class Files..." menu item to get ITunesController to show up as a valid option)
9. Wire the button to your controller's "show_version" method and wire the controller's text_field outlet to the label.

Here's what my project looks like:


Here's what my Ruby "ITunesController" class looks like:

require 'osx/cocoa'

include OSX
class ITunesController < NSObject
    ib_outlet :text_field
    def show_version(sender)
        iTunes = SBApplication.applicationWithBundleIdentifier:'com.apple.iTunes'
        @text_field.setStringValue("iTunes version: #{iTunes.version}")
    end
    ib_action :show_version
end

Here's what the app looks like:


Now you should be able to run the project and get the iTunes version number displayed in your own application. Yeah, the end result is kind of lame but the journey was pretty cool. The interesting bits for me were:

1. My Ruby class extends Cocoa's NSObject class.
2. The class methods ib_outlet and ib_action are parts of the Ruby DSL for doing Cocoa development with Ruby.
3. The RubyCocoa framework makes it really simple to swap out Objective-C for Ruby when doing Cocoa development.
4. Everything else is the same. I still use XCode for my controllers and model and still use Interface Builder to graphically build my GUI and bind it to my code. The only difference is that I get to use Ruby and all of its beauty to get the job done.
5. The downside is that I don't get anything too useful in the way of code completion while in XCode. Still might be worth it if you really dig Ruby.

Yahoo Address Book & Leopard

Leopard's new address book allows you to sync with your Yahoo! contacts.  It's not intuitive so here goes:

1. Open the general tab of Leopard's Address Book preferences.
2. Check "Synchronize with Yahoo!"
3. Click on the Configure Button and enter your Yahoo! ID and Password
4. Open iSync's Preferences (here's where it gets weird)
5. Check "Show status in menu bar"
6. Select "Sync Now" from the new menu bar icon on the right
7. Enjoy!

Of course you should back up everything before you try this.  I've been using Yahoo! Mail for years so it's my most correct and complete contact list.  I'm glad I can now benefit from this in Leopard.  Now if Yahoo! would just be as good as Google and give me IMAP support for free or if Apple would give me a GMail Address Book Sync, I'd be able to use Apple's mail client most of the time.

Now that I think about it, it'd also be nice to have iCal sync up with either Yahoo's or Google's calendar too!