Simple Redis pub/sub

_usage.md

Usage

• Install the redis gem
• Start subscribe.rb with ruby subscribe.rb, this will not exit
• Run ruby publish.rb and you should see the message being received in the output of subscribe.rb

notifications.rb

require 'redis'
require 'json'

class Notifications
  class << self

    def redis
      @redis ||= Redis.new
    end

    def subscribe(channel, &block)
      redis.subscribe(channel.to_s) do |on|

        on.subscribe do |name, active|
          # NOOP
        end

        on.message do |name, payload|
          block.call(decode_payload(payload))
        end

        on.unsubscribe do |name, active|
          # NOOP
        end

      end
    end

    def publish(channel, payload = {})
      redis.publish(channel, encode_payload(payload))
    end

  private

    def encode_payload(payload)
      JSON.generate(payload)
    end

    def decode_payload(payload)
      JSON.parse(payload)
    end

  end
end

publish.rb

require_relative 'notifications'

Notifications.publish('user.sign_in', { user_id: 1 })

subscribe.rb

require_relative 'notifications'

trap(:INT) do
  exit
end

Notifications.subscribe('user.sign_in') do |payload|
  puts "Received payload from user.sign_in => #{payload.inspect}"
end