em-json.rb

require 'eventmachine'
require 'json'
require 'net/http'

EM.run do
  uri = URI('http://guest:[email protected]:15672/api/overview')
  req = Net::HTTP::Get.new(uri.request_uri)
  req.basic_auth(uri.user, uri.password)

  EM::PeriodicTimer.new(1) do
    request = -> {
      Net::HTTP.start(uri.hostname, uri.port) {|http| http.request(req) }
    }
    callback = ->(response) { puts JSON.parse(response.body) }

    EM.defer(request, callback)
  end
end