PeerTube/support/doc/server/code.md

Server code documentation

The server is a web server developed with NodeJS/Express.

Technologies

• NodeJS -> Language
• MongoDB -> Database
• Express -> Web server framework
• Mongoose -> MongoDB object modeling
• WebTorrent -> BitTorrent over WebRTC
• Electron -> To make WebRTC inside NodeJS
• Mocha -> Test framework

Files

The server main file is server.js. The server modules description are in the package.json at the project root. All other server files are in the server directory:

server.js -> app initilization, main routes configuration (static routes...)
config    -> server YAML configurations (for tests, production...)
scripts   -> Scripts files for npm run
server
|__ controllers  -> API routes/controllers files
|__ helpers      -> functions used by different part of the project (logger, utils...)
|__ initializers -> functions used at the server startup (installer, database, constants...)
|__ lib          -> library function (WebTorrent, OAuth2, friends logic...)
|__ middlewares  -> middlewares for controllers (requests validators, requests pagination...)
|__ models       -> Mongoose models for each MongoDB collection (videos, users, pods...)
|__ tests        -> API tests and real world simulations (to test the decentralized feature...)

Conventions

Uses JavaScript Standard Style.

Developing

• Install the dependencies
• Run npm install at the root directory to install all the dependencies
• Run MongoDB
• Run npm run dev to compile the client and automatically run the server. If the client files are already compiled you can simply run NODE_ENV=test node server

The NODE_ENV=test is set to speed up communications between pods (see constants.js).

npm run help gives you all available commands.

If you want to test the decentralization feature, you can easily run 3 pods by running npm run play. The pods password are test1, test2 and test3.

Architecture

The server is composed by:

• a REST API
• a WebTorrent Tracker
• A separate Electron process

The seperate Electron process has the goal to seed videos through WebRTC because WebRTC directly in NodeJS is not usable for now.

When a user uploads a video, the rest API asks the Electron process to seed it (communicate with IPC) and then adds it to its Mongo database.

If a user wants to watch the video, the tracker will indicate all other users that are watching the video + the Electron process.

Newcomers

The server entrypoint is server.js. You can begin to look at this file. Then you can try to understand the controllers: they are the entrypoint of each API request.