Use Redis pub/sub for channels. ⚡ to @mcolyer for the idea!

package.json

@@ -68,7 +68,8 @@
     "todo-tmbundle": "1.0.0",
     "xml-tmbundle": "1.0.0",
     "yaml-tmbundle": "1.0.0",
-    "nslog": "0.1.0"
+    "nslog": "0.1.0",
+    "redis": "0.8.4"
   },
   "devDependencies": {
     "biscotto": "0.0.12",

src/packages/collaboration/lib/guest-session.coffee

@@ -19,7 +19,7 @@ class GuestSession extends Session
   start: ->
     channel = @subscribe("presence-atom")
 
-    channel.on 'pusher:subscription_succeeded', =>
+    channel.on 'channel:open', =>
       console.log 'in the channel', arguments
 
     channel.one 'client-welcome', ({doc, siteId, repoSnapshot}) =>

src/packages/collaboration/lib/host-session.coffee

@@ -41,11 +41,11 @@ class HostSession extends Session
 
     @doc = @createDocument()
     channel = @subscribe("presence-atom")
-    channel.on 'pusher:subscription_succeeded', =>
+    channel.on 'channel:opened', =>
       @trigger 'started'
       @connectDocument(@doc, channel)
 
-    channel.on 'pusher:member_added', =>
+    channel.on 'channel:participant-joined', =>
       @snapshotRepository (repoSnapshot) =>
         welcomePackage =
           siteId: @nextGuestSiteId++

src/packages/collaboration/lib/redis-channel.coffee

@@ -0,0 +1,31 @@
+_ = require 'underscore'
+redis = require 'redis'
+guid = require 'guid'
+
+module.exports =
+class RedisChannel
+  _.extend @prototype, require('event-emitter')
+
+  constructor: (@name) ->
+    @clientId = guid.create().toString()
+
+    @subscribeClient = redis.createClient()
+    @sendClient = redis.createClient()
+    @subscribeClient.on 'error', (error) -> console.error("Error on subscribe client", error)
+    @sendClient.on 'error', (error) -> console.error("Error on send client", error)
+
+    @subscribeClient.subscribe @name, =>
+      console.log "subscribed to channel", @name
+      @send 'channel:participant-joined', @clientId
+      @trigger 'channel:opened'
+
+    @subscribeClient.on 'message', (channelName, message) =>
+      return unless channelName is @name
+      [senderId, eventName, args...] = JSON.parse(message)
+      unless senderId is @clientId
+        console.log "message on channel", eventName, args...
+        @trigger(eventName, args...)
+
+  send: (eventName, args...) ->
+    message = JSON.stringify([@clientId, eventName, args...])
+    @sendClient.publish(@name, message)

src/packages/collaboration/lib/session.coffee

@@ -1,14 +1,14 @@
 _ = require 'underscore'
 keytar = require 'keytar'
 
-RateLimitedChannel = require './rate-limited-channel'
+RedisChannel = require './redis-channel'
 
 module.exports =
 class Session
   _.extend @prototype, require('event-emitter')
 
   subscribe: (channelName) ->
-    new RateLimitedChannel(@getPusherConnection().subscribe(channelName))
+    new RedisChannel(channelName)
 
   getPusherConnection: ->
     @pusher ?= new Pusher '490be67c75616316d386',

src/packages/collaboration/spec/collaboration-spec.coffee

@@ -24,9 +24,9 @@ class ChannelServer
     setTimeout =>
       for client in @getChannelClients()
         if client is channelClient
-          client.trigger 'pusher:subscription_succeeded'
+          client.trigger 'channel:opened'
         else
-          client.trigger 'pusher:member_added'
+          client.trigger 'channel:participant-joined'
     channelClient
 
   getChannelClients: -> _.values(@channelClients)
@@ -53,7 +53,7 @@ class ChannelClient
   send: (eventName, eventData) ->
     @channelServer.send(this, eventName, eventData)
 
-fdescribe "Collaboration", ->
+describe "Collaboration", ->
   describe "joining a host session", ->
     [hostSession, guestSession, pusher, repositoryMirrored] = []