Blog by Piotr Banaszkiewicz

Peer instruction: update 3

The decision has been made, and I switched to a different codebase.

I had one exam this week (Aparatura Automatyzacji, eng. Automation Systems) and five more in next 2-3 weeks, so it is quite challenging for me to find time for peer instruction right now.

I did, however, spend most of this weekend trying to make Pitt broadcasting mode for instructors.

It works! Proof below:

Me as instructor and two students. Having dual monitor setup helps getting this kind of screenshots. (click to enlarge)

As you can see, the layout and design in general is very rough. And so is the code.

This code is mostly based upon multiple events being propagated through sockets.

But I really don’t like the design of these events, and, frankly speaking, I much more prefer a “pub/sub” (publication - subscription) architecture.

At this moment, when the instructor triggers an event, the server has to repropagate it to every student.

In “pub/sub” arch, however, there’s no repropagation in between.

Some people use redis for pub/sub, but I found some really cool protocol: WAMP (don’t confuse it with Windows, Apache, MySQL, PHP stack!).

WAMP authors clearly explain why it is good so please go there and read. Let me just point out a few cool features of WAMP:

  • WAMP is not a NodeJS module, it’s a protocol
  • it can be (and indeed is!) implemented in various languages
  • therefore it’s a solid foundation for a quickly changing service.

What I dislike about WAMP is that at the moment there’s only one leading implementation: Autobahn. And I’m not yet sure if I want to drop NodeJS backend in the future, but if so, then there’s already fast Autobahn|Python.