Created
October 26, 2011 14:20
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Code to listen to redis pubsub channel for events and send them to connected clients
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| source 'http://rubygems.org' | |
| gem "hiredis", "~> 0.3.1" | |
| gem "em-synchrony" | |
| gem 'em-hiredis' | |
| #gem "redis", "~> 2.2.0", :require => ["redis/connection/synchrony", "redis"] | |
| gem "goliath" | |
| #gem 'em-synchrony', :git => 'git://github.com/igrigorik/em-synchrony.git' |
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| <!DOCTYPE html> | |
| <html> | |
| <body> | |
| <h3>Hello SSE!</h3> | |
| <script> | |
| function getQuerystring(key, default_) | |
| { | |
| if (default_==null) default_=""; | |
| key = key.replace(/[\[]/,"\\\[").replace(/[\]]/,"\\\]"); | |
| var regex = new RegExp("[\\?&]"+key+"=([^&#]*)"); | |
| var qs = regex.exec(window.location.href); | |
| if(qs == null) | |
| return default_; | |
| else | |
| return qs[1]; | |
| } | |
| var channel = getQuerystring('channel') || "foo"; | |
| var source = new EventSource('/events?channel=' + channel); | |
| // new connection opened callback | |
| source.addEventListener('open', function(e) { | |
| console.log('connection opened'); | |
| }, false); | |
| // subscribe to unnamed messages | |
| source.onmessage = function(e) { | |
| console.log(e); | |
| document.body.innerHTML += e.data + '<br />'; | |
| alert(e.data); | |
| }; | |
| // connection closed callback | |
| source.addEventListener('error', function(e) { | |
| if (e.eventPhase == EventSource.CLOSED) { | |
| console.log('connection closed'); | |
| } | |
| }, false); | |
| </script> | |
| </body> | |
| </html> |
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| # | |
| # This is now a working example! | |
| # | |
| require 'rubygems' | |
| require 'em-hiredis' | |
| require 'goliath' | |
| class Wizard < Goliath::API | |
| use Rack::Static, :urls => ["/index.html"], :root => Goliath::Application.app_path("public") | |
| use Goliath::Rack::Params | |
| attr_accessor :redis | |
| def response(env) | |
| path = env[Goliath::Request::REQUEST_PATH] | |
| return [404, {}, "Not found"] unless path == "/events" | |
| channel = env.params[:channel] | |
| return [404, {}, "Channel required"] if channel.nil? || channel == "" | |
| env.logger.info "Connecting to channel '#{channel}' for updates" | |
| env['redis'] = EM::Hiredis.connect | |
| env['redis'].subscribe(channel) | |
| env['redis'].on(:message) do |chn, msg| | |
| env.logger.info "Message received from channel #{chn}: #{msg} (We're looking for #{channel})" | |
| if chn === channel | |
| res = env.stream_send("data:#{msg}\n\n") | |
| end | |
| end | |
| streaming_response(200, {'Content-Type' => 'text/event-stream'}) | |
| end | |
| def on_close(env) | |
| path = env[Goliath::Request::REQUEST_PATH] | |
| return unless path == "/events" | |
| channel = env.params[:channel] | |
| return if channel.nil? || channel == "" | |
| env.logger.info "Connection closed, Unsubscribing." | |
| env['redis'].unsubscribe(channel) | |
| env['redis'].close | |
| end | |
| end |
I'm probably "a bit" late, but eventually this can help someone stumbling upon this in the next time so I will share it anyway. The reason for the error is that em-hiredis has been updated.
This is from their readme:
The regular EM::Hiredis::Client no longer understands pubsub messages - this logic has been moved to EM::Hiredis::PubsubClient. The pubsub client can either be initialized directly (see code) or you can get one connected to the same redis server by calling #pubsub on an existing EM::Hiredis::Client instance.
Hope this helps somebody.
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Trying to run this, but running into an issue.
When I load index.html, I get this error:
[14029:INFO] 2013-06-26 21:51:01 :: Status: 200, Content-Length: 1074, Response Time: 19.60ms
[14029:INFO] 2013-06-26 21:51:01 :: Connecting to channel 'foo' for updates
[14029:ERROR] 2013-06-26 21:51:01 :: Use pubsub client
... long stack trace ...
Any ideas?
I do have redis installed.