CanJam

This was a project that I worked on with three other students for our Concurrency course; Skylar Gilfeather, Cecelia Crumlish, and Roger Burtonpatel. You can find our detailed final report here.

CanJam is a multiplayer melody maker that allows users to play music with each other across multiple laptop instances. We were inspired by the Chrome Music Lab Melody Maker. Our goal with this project is to build a fun, colorful and fun-to-play visual interface, including different musical instruments.

Project Goal

The minimum deliverable for CanJam was to display unique colors and play unique synth sounds for each user interacting with the canvas. This goal was achieved, supporting four different synth types. In the future, optimizing the synth generation process, or using a different sound library entirely, could allow us to generate a wider variety of sounds.

Additionally, our minimum deliverable required that users could connect CanJam canvases independent of a central server - i.e., CanJam should be peer-to-peer. In our protocol, users manage setup communications and share sound packets with their peers in a connected cluster of CanJam instances. However, because CanJam peers share sounds by unreliably broadcasting large batches of small Sound packets, it was difficult to achieve the illusion of continuously playing sound. It sounds more like short beats of sound. However, despite this drawback, our testing showed that at least six CanJam users could collaboratively play on the same canvas with no increase in these performance issues when playing a peer's incoming sounds.

The Jamsocket Module

One of my largest contributions to this project was the jamsocket module - a socket wrapper that provides both reliable and unreliable UDP communication methods. I designed the jamsocket protocol to provide speedy (but unreliable) message sending methods alongside slower (but reliable) message sending methods. Both features operate over the same UDP socket. Key features of the Jamsocket class include:

• It uses the socket library to create and manage a UDP socket.
• It provides methods to send and receive data, with optional reliability.
• It uses a separate thread that listens for incoming packets and handles timeouts for outstanding packets.
• It uses different types of packets, including Ack, Data, DataNoAck, Skip, Die, Hello, and HelloAck to send data and maintain connections with other Jamsockets.

The Jamsocket class is used by the multithreaded InboundWorker and OutboundWorker classes to send and receive messages over the network. Sound messages are sent unreliably to achieve low-latency, while all other messages are sent reliably to ensure a consistent room state.

Conclusion

I used many of the skills I gained from my other networking courses at Tufts for this project. It gave me full creative freedom to design a peer-to-peer protocol and a neat socket wrapper protocol, as well as learning tons about concurrency in Python! As four undergraduate seniors, it put our project management skills to the test to delegate work efficiently and design decoupled modules that interfaced well together.

If you're interested in the real nitty gritty, find our final report here, and find the full codebase here.