ARCHITECTURE.md

   1 # Architecture
   2
   3 ## Vocabulary
   4
   5   - **Fediverse:** several servers following one another, several users
   6     following each other. Designates federated communities in general.
   7   - **Vidiverse:** same as Fediverse, but federating videos specifically.
   8   - **Instance:** a server which runs PeerTube in the fediverse.
   9   - **Origin instance:** the instance on which the video was uploaded and which
  10     is seeding (through the WebSeed protocol) the video.
  11   - **Cache instance:** an instance that decided to make available a WebSeed
  12     of its own for a video originating from another instance. It sends a `ptCache`
  13     activity to notify the origin instance, which will then update its list of
  14     WebSeeds for the video.
  15   - **Following:** the action of a PeerTube instance which will follow another
  16     instance (subscribe to its videos).
  17
  18 ## Base
  19
  20 ### Communications
  21   * All the communication between the instances are signed with [Linked Data
  22     Signatures](https://w3c-dvcg.github.io/ld-signatures/) with the private key
  23     of the account that authored the action.
  24   * We use the [ActivityPub](https://www.w3.org/TR/activitypub/) protocol (only
  25     server-server for now). Object models could be found in
  26     [shared/models/activitypub
  27     directory](/shared/models/activitypub).
  28   * All the requests are retried several times if they fail.
  29
  30 ### Instance
  31   * An instance has a websocket tracker which is responsible for all videos
  32     uploaded by its users.
  33   * An instance has an administrator that can follow other instances.
  34   * An instance can be configured to follow back automatically.
  35   * An instance can blacklist other instances (only used in "follow back"
  36     mode).
  37   * An instance cannot choose which other instances follow it, but it can
  38     decide to **reject all** followers.
  39   * After having uploaded a video, the instance seeds it (WebSeed protocol).
  40   * If a user wants to watch a video, they ask its instance the magnet URI and
  41     the frontend adds the torrent (with WebTorrent), creates the HTML5 video
  42     player and streams the file into it.
  43   * A user watching a video seeds it too (BitTorrent). Thus another user who is
  44     watching the same video can get the data from the origin server and other
  45     users watching it.