Pub-Sub envelope subscriber in Ruby

#! /usr/bin/env ruby
require 'zmq'
context = ZMQ::Context.new
subscriber = context.socket ZMQ::SUB
subscriber.connect "tcp://*:5563"
subscriber.setsockopt ZMQ::SUBSCRIBE,'B'
while true
# Two recv s because of the multi-part message.
address = subscriber.recv
content = subscriber.recv
puts "[#{address}] #{content}"
end