Created
May 5, 2011 16:30
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web sockets with eventmachine and redis pub/sub
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| # A sample Gemfile | |
| source "http://rubygems.org" | |
| gem "redis" | |
| gem 'eventmachine', :git => 'git://github.com/eventmachine/eventmachine.git' | |
| gem "em-hiredis" | |
| # gem "em-synchrony" | |
| gem "em-websocket" |
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| require 'rubygems' | |
| require 'bundler/setup' | |
| require 'em-websocket' | |
| require 'em-hiredis' | |
| EM.run do | |
| @channel = EM::Channel.new | |
| @redis = EM::Hiredis.connect | |
| puts 'subscribing to redis' | |
| @redis.subscribe('ws') | |
| @redis.on(:message){|channel, message| | |
| puts "redis -> #{channel}: #{message}" | |
| @channel.push message | |
| } | |
| # Creates a websocket listener | |
| EventMachine::WebSocket.start(:host => '0.0.0.0', :port => 8081) do |ws| | |
| puts 'Establishing websocket' | |
| ws.onopen do | |
| puts 'client connected' | |
| puts 'subscribing to channel' | |
| sid = @channel.subscribe do |msg| | |
| puts "sending: #{msg}" | |
| ws.send msg | |
| end | |
| ws.onmessage { |msg| | |
| @channel.push "<#{sid}>: #{msg}" | |
| } | |
| ws.onclose { | |
| @channel.unsubscribe(sid) | |
| } | |
| end | |
| end | |
| end |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>Websockets!</title> | |
| <script type="text/javascript"> | |
| function onMessage(evt) { | |
| con = document.getElementById("console"); | |
| con.innerHTML += evt.data; | |
| con.innerHTML += '<br />'; | |
| } | |
| websocket = new WebSocket("ws://localhost:8081"); | |
| websocket.onmessage = function(evt) { onMessage(evt); }; | |
| </script> | |
| </head> | |
| <body> | |
| <div id="console"> | |
| </div> | |
| </body> | |
| </html> |
Thanks for the example! almost 4 years later exactly and this still works with only one change
line 9 is now: @redis = EM::Hiredis.connect.pubsub
@redis = EM::Hiredis.connect.pubsub + 1
Otherwise EventMachine::WebSocket.start can not use redis, it will block by @redis.subscribe
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thanks @gvarela. It works. You save my day!