path: root/support/doc/server/code.md

# Server code documentation

The server is a web server developed with [NodeJS](https://nodejs.org)/[Express](http://expressjs.com).


## Technologies

  * [NodeJS](https://nodejs.org) -> Language
  * [MongoDB](https://www.mongodb.com/) -> Database
  * [Express](http://expressjs.com) -> Web server framework
  * [Mongoose](http://mongoosejs.com/) -> MongoDB object modeling
  * [WebTorrent](https://webtorrent.io/) -> BitTorrent over WebRTC
  * [Electron](http://electron.atom.io/) -> To make WebRTC inside NodeJS
  * [Mocha](https://mochajs.org/) -> Test framework


## Files

The server main file is [server.js](https://github.com/Chocobozzz/PeerTube/blob/master/server.js).
The server modules description are in the [package.json](https://github.com/Chocobozzz/PeerTube/blob/master/package.json) at the project root.
All other server files are in the [server](https://github.com/Chocobozzz/PeerTube/tree/master/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](http://standardjs.com/).


## Developing

  * Install [the dependencies](https://github.com/Chocobozzz/PeerTube#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](https://github.com/Chocobozzz/PeerTube/blob/master/server/initializers/constants.js#L71)).

`npm run help` give you all available commands.

If you want to test the decentralization feature, you can easily run 3 pods by runnin `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.

![Architecture scheme](https://github.com/Chocobozzz/PeerTube/blob/master/support/doc/server/upload-video.png)

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

If an 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](https://github.com/Chocobozzz/PeerTube/blob/master/server.js). You can begin to look at this file.
Then you can try to understand the [controllers](https://github.com/Chocobozzz/PeerTube/tree/master/server/controllers): they are the entrypoint of each API request.