PeerTube/support/doc/server/code.md

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# Server code documentation
The server is a web server developed with [TypeScript](https://www.typescriptlang.org/)/[Express](http://expressjs.com).
## Technologies
* [TypeScript](https://www.typescriptlang.org/) -> Language
* [PostgreSQL](https://www.postgresql.org/) -> Database
* [Express](http://expressjs.com) -> Web server framework
* [Sequelize](http://docs.sequelizejs.com/en/v3/) -> SQL ORM
* [WebTorrent](https://webtorrent.io/) -> BitTorrent tracker and torrent creation
* [Mocha](https://mochajs.org/) -> Test framework
## Files
The server main file is [server.ts](https://github.com/Chocobozzz/PeerTube/blob/master/server.ts).
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.ts -> 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 -> Sequelize models for each SQL tables (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 `yarn install` at the root directory to install all the dependencies
* Run PostgreSQL and create the database `peertube_dev`.
* Run `npm run dev:server` to run the server, watch server files modifications and restart it automatically. The server (API + client) listen on `localhost:9000`.
The `NODE_ENV=test` is set to speed up communications between pods (see [constants.ts](https://github.com/Chocobozzz/PeerTube/blob/master/server/initializers/constants.ts)).
`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 (throught Express framework)
* a WebTorrent Tracker
A video is seeded by the server throught the [WebSeed](http://www.bittorrent.org/beps/bep_0019.html) protocol (HTTP).
![Architecture scheme](https://github.com/Chocobozzz/PeerTube/blob/master/support/doc/server/upload-video.png)
When a user uploads a video, the rest API create the torrent file and then adds it to its database.
If a user wants to watch the video, the tracker will indicate all other users that are watching the video + the HTTP url for the WebSeed.
## Newcomers
The server entrypoint is [server.ts](https://github.com/Chocobozzz/PeerTube/blob/master/server.ts). 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.