pubsub.rb

# PubSub with a microservice: send a message to a fleet of workers, 
# let one of workers pick the task and send the result message directly to the requester.

# the manager
# pub.rb
require 'redis'

trap(:INT) { puts 'Bye!'; exit }
r = Redis.new

loop do
  input = gets.strip
  r.rpush 'requests', input
  r.subscribe input do |on|
    on.message do |c, m|
      puts "microservice said: #{m}"
      r.unsubscribe
    end
  end
end

# the microservice
# sub.rb
require 'redis'

trap(:INT) { puts 'Bye!'; exit }
r = Redis.new

loop do
  message = r.blpop('requests', 0).last
  r.publish message, "your message '#{message}' has been processed"
end