recv.rb

require 'rubygems'
require 'zmq'

z = ZMQ::Context.new
s = z.socket(ZMQ::UPSTREAM)
s.connect "tcp://127.0.0.1:5555"

while true
  puts s.recv
end

send.rb

require 'rubygems'
require 'zmq'

z = ZMQ::Context.new
s = z.socket(ZMQ::DOWNSTREAM)
s.bind("tcp://127.0.0.1:5555")

ARGV[0].to_i.times do |c|
  s.send(c.to_s)
end