url_service_demo.rb

# See: http://docs.oracle.com/javafx/2/threads/jfxpub-threads.htm

require 'jrubyfx'
require 'open-uri'

class FirstLineURLTask < Java::javafx.concurrent.Task
  def initalize(url)
    @url = url
  end

  def call
    first_line = open(@url) do |f|
      f.readline
    end
    return first_line
  end
end

class FirstLineService < Java::javafx.concurrent.Service
  include JRubyFX
  property_accessor :url
  def initialize
    super()
    @url = SimpleStringProperty.new
  end

  protected
  def createTask
    return FirstLineURLTask.new(@url)
  end
end

class FirstLineServiceApp < JRubyFX::Application
  def start(stage)
    service = FirstLineService.new
    service.url = "http://google.com"
    service.on_succeeded do |t| 
      puts "done"
    end
    service.start()
    with(stage,
         title: "Service Demo: Retrieves first line of URL in background", width: 300, height: 150) do
      layout_scene do
        label(id: "result", text: "working")
      end
    end
    stage.show
  end
end

FirstLineServiceApp.launch
# I'll get
=begin
% jruby url_service_demo.rb
Exception running Application:
#<ArgumentError: wrong number of arguments (1 for 0)>
url_service_demo.rb:39:in `start'
/home/max/Programmierung/gsoc/jruby/lib/ruby/gems/shared/gems/jrubyfx-1.0.0-java/lib/jrubyfx/java_fx_impl.rb:120:in `launch_app_after_platform'
org/jruby/gen/InterfaceImpl299080017.gen:13:in `run'
=end