Add some docs to the message queue

lib/message-queue.js

@@ -1,12 +1,18 @@
 
+/*
+  A Module that exposes a message queue. One can subscribe to channels and receive
+  callbacks when someone publishes messages to these channels
+*/
 
 var Subscribers = {};
 
+// Subscription objects are returned by the subscribe function.
 function Subscription (channels, cb) {
   this.channels = channels;
   this.cb = cb;
 }
 
+// Call this method to unsubscribe a subscription
 Subscription.prototype.unsubscribe = function () {
   var cb   = this.cb;
   this.channels.forEach(function (channel) {
@@ -24,6 +30,8 @@ Subscription.prototype.unsubscribe = function () {
   })
 }
 
+// Subscribe to an array of channels (TODO make this an array or string)
+// listenerCB will be fired when an event is published to one of the channels.
 exports.subscribe = function (channels, listenerCB) {
   if(typeof listenerCB != "function") {
     throw new Error("subscribe needs a callback parameter");
@@ -38,6 +46,7 @@ exports.subscribe = function (channels, listenerCB) {
   return new Subscription(channels, listenerCB);
 }
 
+// Publish an event of data to a channel
 exports.publish = function (channel, data) {
   var subs = Subscribers[channel];
   if(subs) {