00_sync.rb

require 'net/http'                                                                                                                              
require 'uri'                                                                                                                                   
                                                                                                                                                
random_url = URI('http://www.random.org/integers/?num=1&min=1&max=6&col=1&base=10&format=plain&rnd=new')                                        
                                                                                                                                                
ints = []                                                                                                                                       
                                                                                                                                                
resp = Net::HTTP.get_response(random_url)                                                                                                       
ints << resp.body.strip                                                                                                                         
puts "Random integers: #{ints.inspect}"                                                                                                         
                                                                                                                                                
resp = Net::HTTP.get_response(random_url)                                                                                                       
ints << resp.body.strip                                                                                                                         
puts "Random integers: #{ints.inspect}"                                                                                                         
                                                                                                                                                
resp = Net::HTTP.get_response(random_url)                                                                                                       
ints << resp.body.strip                                                                                                                         
puts "Random integers: #{ints.inspect}"                                                                                                         
                                                                                                                                                
resp = Net::HTTP.get_response(random_url)                                                                                                       
ints << resp.body.strip                                                                                                                         
puts "Random integers: #{ints.inspect}"                                                                                                         
                                                                                                                                                
resp = Net::HTTP.get_response(random_url)                                                                                                       
ints << resp.body.strip                                                                                                                         
puts "Random integers: #{ints.inspect}"

01_callbacks.rb

require 'bundler/setup'                                                                                                                         
require 'eventmachine'                                                                                                                          
require 'em-http-request'                                                                                                                       
                                                                                                                                                
random_url = URI('http://www.random.org/integers/?num=1&min=1&max=6&col=1&base=10&format=plain&rnd=new')                                        
                                                                                                                                                
ints = []                                                                                                                                       
                                                                                                                                                
EM.run do                                                                                                                                       
  http = EM::HttpRequest.new(random_url).get.callback do                                                                                        
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    http = EM::HttpRequest.new(random_url).get.callback do                                                                                      
      ints << http.response.strip                                                                                                               
      puts "Random integers: #{ints.inspect}"                                                                                                   
                                                                                                                                                
      http = EM::HttpRequest.new(random_url).get.callback do                                                                                    
        ints << http.response.strip                                                                                                             
        puts "Random integers: #{ints.inspect}"                                                                                                 
                                                                                                                                                
        http = EM::HttpRequest.new(random_url).get.callback do                                                                                  
          ints << http.response.strip                                                                                                           
          puts "Random integers: #{ints.inspect}"                                                                                               
                                                                                                                                                
          http = EM::HttpRequest.new(random_url).get.callback do                                                                                
            ints << http.response.strip                                                                                                         
            puts "Random integers: #{ints.inspect}"                                                                                             
                                                                                                                                                
            puts 'stopping'                                                                                                                     
            EM.stop                                                                                                                             
          end                                                                                                                                   
        end                                                                                                                                     
      end                                                                                                                                       
    end                                                                                                                                         
  end                                                                                                                                           
end

02_promise.rb

require 'bundler/setup'                                                                                                                         
require 'eventmachine'                                                                                                                          
require 'em-http-request'                                                                                                                       
                                                                                                                                                
random_url = URI('http://www.random.org/integers/?num=1&min=1&max=6&col=1&base=10&format=plain&rnd=new')                                        
                                                                                                                                                
ints = []                                                                                                                                       
                                                                                                                                                
EM.run do                                                                                                                                       
  EM::HttpRequest.new(random_url).promise_get.then { |http|                                                                                     
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    EM::HttpRequest.new(random_url).promise_get                                                                                                 
  }.then { |http|                                                                                                                               
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    EM::HttpRequest.new(random_url).promise_get                                                                                                 
  }.then { |http|                                                                                                                               
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    EM::HttpRequest.new(random_url).promise_get                                                                                                 
  }.then { |http|                                                                                                                               
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    EM::HttpRequest.new(random_url).promise_get                                                                                                 
  }.then { |http|                                                                                                                               
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    EM.stop                                                                                                                                     
  }                                                                                                                                             
end

03_fiber.rb

require 'fiber'                                                                                                                                 
require 'bundler/setup'                                                                                                                         
require 'eventmachine'                                                                                                                          
require 'em-http-request'                                                                                                                       
                                                                                                                                                
random_url = URI('http://www.random.org/integers/?num=1&min=1&max=6&col=1&base=10&format=plain&rnd=new')                                        
                                                                                                                                                
ints = []                                                                                                                                       
                                                                                                                                                
def fiber_get(url)                                                                                                                              
  fiber = Fiber.current                                                                                                                         
                                                                                                                                                
  http = EM::HttpRequest.new(url).get                                                                                                           
                                                                                                                                                
  http.callback { fiber.resume(http) }                                                                                                          
                                                                                                                                                
  return Fiber.yield                                                                                                                            
end                                                                                                                                             
                                                                                                                                                
EM.run do                                                                                                                                       
  Fiber.new {                                                                                                                                   
    http = fiber_get(random_url)                                                                                                                
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    http = fiber_get(random_url)                                                                                                                
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    http = fiber_get(random_url)                                                                                                                
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    http = fiber_get(random_url)                                                                                                                
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    http = fiber_get(random_url)
    ints << http.response.strip                                                                                                                 
    puts "Random integers: #{ints.inspect}"                                                                                                     
                                                                                                                                                
    EM.stop                                                                                                                                     
  }.resume                                                                                                                                      
end