Using Redis as Message Broker for RPC (Server)

redis_server.rb

#!/usr/bin/env ruby
require 'redis'
require 'json'
require './calculator'

calculator = Calculator.new

# connect to Redis
redis_client = Redis.connect(url: 'redis://localhost:6379')

while true
  # pop last element off our list in a blocking fashion
  channel, request = redis_client.brpop('calc')

  request = JSON.parse request

  # call a method on the calculator instance, passing along params
  args   = request['params'].unshift(request['method'])  
  result = calculator.send *args

  reply = {
    'id' => request['id'],
    'result' => result,
    'jsonrpc' => '2.0'
  }

  # 'respond' by inserting our reply at the tail of a 'reply'-list
  redis_client.rpush(request['id'], JSON.generate(reply))
  
  # set an expire time for our list to make sure we don't leak
  redis_client.expire(req_message['id'], 30)
end