ZeroMQ

• The socket library that acts as a concurrency framework.
• Carries messages across inproc, IPC, TCP, and multicast.
• Connect N-to-N via fanout, pubsub, pipeline, request-reply.
• Asynch I/O for scalable multicore message-passing apps.
• 40+ languages including C, C++, Java, .NET, Python, Ruby, NodeJS

Who is using?

• AT&T
• Cisco
• NASA
• Zynga
• Spotify
• Samsung Electronics
• CERN

Request

#!/usr/bin/env ruby

require 'rubygems'
require 'ffi-rzmq'

context = ZMQ::Context.new

puts "Connecting to hello world server..."
requester = context.socket(ZMQ::REQ)
requester.connect("tcp://localhost:5555")

0.upto(9) do |request_nbr|
  puts "Sending request #{request_nbr}..."
  requester.send_string "Hello"

  reply = ''
  requester.recv_string(reply)

  puts "Received reply #{request_nbr}: [#{reply}]"
end

Response

#!/usr/bin/env ruby

require 'rubygems'
require 'ffi-rzmq'

context = ZMQ::Context.new

puts "Starting Hello World server..."

socket = context.socket(ZMQ::REP)
socket.bind("tcp://*:5555")

while true do
  request = ''
  rc = socket.recv_string(request)

  puts "Received request. Data: #{request.inspect}"

  sleep 1
  socket.send_string("world")
end

Subscriber A

#!/usr/bin/env ruby

require 'ffi-rzmq'

context = ZMQ::Context.new
subscriber = context.socket ZMQ::SUB
subscriber.connect "tcp://localhost:5563"
subscriber.setsockopt ZMQ::SUBSCRIBE, 'ALL'
subscriber.setsockopt ZMQ::SUBSCRIBE, 'A'

loop do
  # Two recv s because of the multi-part message.
  address = ''
  subscriber.recv_string address

  content = ''
  subscriber.recv_string content

  puts "[#{address}] #{content}"
end

Subscriber B

#!/usr/bin/env ruby

require 'ffi-rzmq'

context = ZMQ::Context.new
subscriber = context.socket ZMQ::SUB
subscriber.connect "tcp://localhost:5563"
subscriber.setsockopt ZMQ::SUBSCRIBE, 'ALL'
subscriber.setsockopt ZMQ::SUBSCRIBE, 'B'

loop do
  # Two recv s because of the multi-part message.
  address = ''
  subscriber.recv_string address

  content = ''
  subscriber.recv_string content

  puts "[#{address}] #{content}"
end

Publisher

#!/usr/bin/env ruby

require 'ffi-rzmq'

context = ZMQ::Context.new
publisher = context.socket ZMQ::PUB
publisher.bind "tcp://*:5563"

loop do
  publisher.send_string 'A', ZMQ::SNDMORE
  publisher.send_string "Message for A"

  publisher.send_string 'B', ZMQ::SNDMORE
  publisher.send_string "Message for B"

  publisher.send_string 'ALL', ZMQ::SNDMORE
  publisher.send_string "Message for ALL"

  sleep 1
end