basic event machine pubsub for ChicagoRuby

server.rb

#!/usr/bin/env ruby

require "rubygems"
require "eventmachine"

class PubSubServer < EM::Connection 
  attr_accessor :channels
  
  SubscriberChannel = EM::Channel.new
  
  def self.start(host = '0.0.0.0', port = 8080)
    puts "starting PubSubServer"
    EM.start_server(host, port, self)
  end
  
  def initialize
    super
    self.channels = []
  end
    
  def receive_data(data)
    puts data.inspect
    message = Message.new(data)
    
    case message.command
    when "SUBSCRIBE"
      if channels.empty?
        SubscriberChannel.subscribe do |pushed_message|
          if channels.include?(pushed_message.channel)
            send_data(pushed_message.message)
          end
        end
      end
      channels << message.channel
      
      send_data("OK\n")
      
    when "SEND"
      SubscriberChannel.push(message)
      send_data("OK\n")
      
    else
      send_data("I don't know what #{message.command} is\n")
    end
  end
end

class Message
  attr_reader :command, :channel, :message
  
  def initialize(data)
    @data = data
    parse_data
  end
  
  def parse_data
    @command, @channel, @message = @data.strip.split(' ', 3)
  end
end

EventMachine::run do
  PubSubServer.start
end

subscriber.rb

#!/usr/bin/env ruby

require "rubygems"
require "eventmachine"

module Subscriber
  def post_init
    EM.defer do
      ARGV.each do |channel|
        puts "subscribing to #{channel}"
        send_data("SUBSCRIBE #{channel}")
        sleep 1
      end
    end
  end
  
  def receive_data(data)
    puts data.inspect
  end
end

EventMachine.run do
  EventMachine.connect "0.0.0.0", 8080, Subscriber
end