SockBit: a Socket.IO + RabbitMQ proof of concept

Blog post

This code accompanies my blog post at http://dev.imagineeasy.com/post/91224992649/the-realtime-web-with-socket-io-and-rabbitmq which I have copied into the docs directory in this repo.

Summary

This project shows how Socket.IO can be used as a browser-server message transport layer, forwarding application instructions into a messaging queue (RabbitMQ) from which a daemon-based application core can pop jobs off and perform them.

In addition to allowing Socket.IO to scale without need for shared storage or syncing within Socket.IO, it also completely decouples the application logic from this browser-server message transport. This frees us from the need to implement the transport and application layers on the same platform or in the same language, as well as allowing for change down the road. We can now write the application in PHP (as here), or Hack, or Go ...

We can also replace Socket.IO with the Ruby implementation of Faye, or the Python implementation of Autobahn, without affecting the application core.

In this example, when the user changes the textarea value in the browser, the following occurs:

• Browser sends note_updated message to server
• Server queues an update job in RabbitMQ
• Application process pops job and executes update
• Application process broadcasts the update via RabbitMQ to the listening Socket.IO instances
• Socket.IO notifies browsers of the update

Not implemented

• Access control
• Error handling
• http://en.wikipedia.org/wiki/Operational_transformation for edit conflicts
• Socket.IO rooms, i.e. only forwarding the broadcasts to the browsers viewing the affected project

Running

$ vagrant ssh

# in vagrant shell, start your processes, e.g.:
$ cd /vagrant/
$ nodejs socketio_server.js 8080 &
$ nodejs socketio_server.js 8081 &
$ php application/sockbit.php &

Now point separate browser sessions to

• http://33.33.34.101:8080
• http://33.33.34.101:8081