app.rb

require 'bundler'
Bundler.require

class App < Sinatra::Base
  helpers Sinatra::Streaming

  get '/' do
    subscriber = EM::Hiredis.connect
    subscriber.psubscribe '*'

    stream :keep_open do |out|
      subscriber.on(:pmessage) do |key, channel, message|
        subscriber.punsubscribe '*' if out.closed?

        out << "#{key}, #{channel}, #{message}" unless out.closed?
      end
    end
  end
end

Gemfile

source 'https://rubygems.org'

gem 'sinatra'
gem 'sinatra-contrib', require: 'sinatra/streaming'

group :development do
  gem 'thin'
  gem 'pry-rails'
end

gem 'eventmachine', "= 1.0.0.rc.4"
gem "redis", "~> 3.0"
gem "hiredis", "~> 0.4.5"
gem 'em-hiredis'

javascript

jQuery doesn't support that, but you can do that with plain XHR:

var xhr = new XMLHttpRequest()
xhr.open("GET", "/test/chunked", true)
xhr.onprogress = function () {
  alert("PROGRESS: " + xhr.responseText)
}
This works in all modern browsers, including IE 10. W3C specification here.

The downside here is that xhr.responseText contains an accumulated response. You can use substring on it, but a better idea is to use the responseType attribute and use slice on an ArrayBuffer.


http://stackoverflow.com/questions/6789703/how-to-write-javascript-in-client-side-to-receive-and-parse-chunked-response-i/12280916#12280916