A quick test to mess around with em-synchrony.

Gemfile

source :rubygems

gem "eventmachine"
gem "em-synchrony", :require => "em-synchrony"
gem "em-http-request", :require => "em-http"

sync_test.rb

#!/usr/bin/env ruby
require "rubygems"
require "bundler"
require "bundler/setup"

require "json"
require "em-synchrony"

URL     = "YOUR_SERVER/services/user/account"
request = {}

request[:body] = {
  "action"            => "authenticateUser",
  "screenNameOrEmail" => "your_username",
  "password"          => "super_secret_password"
}.to_json


require "em-http"
EM.run {
  puts "EM start"

  http = EventMachine::HttpRequest.new(URL).post(request)
  http.callback {
    resp = JSON.parse http.response
    puts resp
    puts "EM Stop"
    EM.stop
  }

  puts "EM end of block"
}

require "em-synchrony/em-http"
EventMachine.synchrony {
  puts "EM Sync start"

  http = EM::Synchrony.sync EventMachine::HttpRequest.new(URL).apost(request)
  puts JSON.parse http.response

  puts "EM Sync end of block"
  EM.stop
}

When this example is run, we see "EM Stop" output before the result of the related request. The second request outputs "EM sync start" and related messages in the order which they appear in the code.