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Introduction

Goal

A Peer-to-Peer (P2P) chat application.

Process

  1. Set up a Trello Board and GitHub repo.
  2. Researched P2P logic (What is P2P, how does it work etc.)
  3. Considered creating Python P2P built from scratch
    • But... then we realized we had very little time.
  4. Looked into javascript ideas, discovered WebRTC through research!
  5. Used PeerJS as basis for application and went from there adding features until we ran out of time.

Components

images/diagram.png

PeerJS (and NodeJS)

  • PeerJS is a API that uses WebRTC for P2P communication.
    • WebRTC (Web Real Time Communication) is a relatively new idea. It’s purpose is to allow web browsers to communicate directly with each other.
    • Currently WebRTC is supported in Chrome, FireFox and Opera.
    • WebRTC can be used for chat, videochat, and file sharing.
  • PeerJS adds a layer between our code and WebRTC
    • Peers: Webbrowser tabs which are assigned ID’s which are needed to form connections.
    • PeerJS offers a free cloud server which is used to assign ID’s and broker connections between peers. NodeJS (which is really cool btw) is used to power the PeerServer.
      • Note: You can also run your own NodeServer, we were doing this at first, but why pass up free hosting.
      • NO DATA goes to the cloud server once the connection is established. In this way the actual communications are P2P.
  • Connections: Two Peers can connect to each other via their ID’s. Connections are strictly between two peers.

Javascript

We wrote a script which implemented PeerJS and added some features.

  1. We added multichat. PeerJS connections are strictly one-to-one. To add multichat, we made it so that when a Peer starts a connection, it informs all of its current Peers of the new Peer’s ID and prompts them to connect as well.
    • In this way all Peers are connected to all other Peers via several one-to-one connections. Then, if any Peer drops out all of the other Peer’s simply end that one connection and they can still communicate with everyone else.
    • You can still whisper particular Peer’s in a group conversation.
  2. We added the option of public sharing of ID’s (powered by Twitter). PeerJS is set up in such a way that you must know another Peer’s ID in order to connect to them. This is great for private chat, but we wanted a public feature.
    • We added the option to share your ID with the general public. We set up a bot to tweet your ID and a topic of your choice. The Tweets are displayed in the app so you can quickly connect to anonymous Peers to chat about topics you find interesting.
  3. We also added the option to save your chat log (powered by EverNote). Similar to the Twitter bot, we can automate posting of chats to Evernote.
  4. We wanted to add encryption, but we found out via research that WebRTC already implements some forms of encryption (AES encryption) plus we were running out of time :o

HTML and CSS

  • We used HTML and CSS to style our web application and make it look awesome.

Python

  • Python is used to power the Twitter and Evernote bot. We also used Flask and Heroku for this.

Demo

We will now Demo the App

Distributed Aspects

  • P2P Communication - lots of one-to-one connections set up between Peers allows the addition or removal of individual Peers. No central server.
  • Use of CloudServer to broker connections
  • Use of Twitter as “free broadcasting medium” for Topic/ID pairs.
  • Use of Evernote as “free storage” for chat logs.
  • Use of Heroku to host Twitter/Evernote Bot.

What we Learned

  • Learned a lot about Javascript (as well as HTML and CSS)
  • Learned how to make bots to tweet etc.
  • Learned how to make javascript and python talk to eachother.
  • Learned about a up and rising area of computerscience (WebRTC)
  • Made a fun little chatapp

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