6.5 KiB
Owncast Backend Architecture
This is a work in progress document detailing the future backend architecture of Owncast. It should be seen as a living document until a refactor of the backend is complete.
Dependencies
Dependencies are services that are required across the application. This can be things like the chat service or a data repository for config values or user data.
Note: A better name that "dependencies" might be clearer. Perhaps "services" or "providers".
TODO: Have a complete list of dependencies.
Data Repositories
The repository pattern provides a layer of abstraction between the application and the data store, allowing the application to interact with the data store through a well-defined interface, rather than directly accessing the data store. This helps to decouple the application from the data store.
TODO: List out the repositories and what they do.
Learn more about the repository pattern.
Application Controller
The AppController has references to all the dependencies and serves as an arbiter between consumers of these services and the services themselves.
A reference to the AppController is passed in to the all the core functionality in the application and each package would have its own interface that AppController implements. This can include getting access to dependency services like getting access to the chat service, getting access to the config repository values or knowing application state such as if a stream is live or how many viewers are watching via metrics.
TODO: Show examples of how the application is passed in to packages and how to reference dependencies through it.
Diagram
%% Owncast backend architecture.
%% See https://jojozhuang.github.io/tutorial/mermaid-cheat-sheet/
%% for a cheat sheet on creating this diagram.
%% Paste this document in https://mermaid.live as a quick way to edit.
%% TODO: Add links between nodes and the actual code.
%% This is a graph style diagram, Top Down.
graph TD
%% Define Nodes and Subgraphs
subgraph VideoPipeline[Video Pipeline]
VideoTranscoder(fa:fa-video Video Transcoder)
RTMPService[fa:fa-video RTMP Service]
end
subgraph ChatService[fa:fa-comment Chat Service]
end
subgraph Dependencies
OutboundWebhooks[Outbound]
App{Application}
ChatService--->App
Webhooks--->App
ConfigRepository(fa:fa-hard-drive Config Repository)--->App
UserRepository(fa:fa-hard-drive User Repository)--->App
APRepository(fa:fa-hard-drive ActivityPub Repository)--->App
NotificationsRepository(fa:fa-hard-drive Notifications Repository)--->App
ChatRepository(fa:fa-hard-drive Chat Repository)
Database(fa:fa-hard-drive Database)--->ConfigRepository
Database--->UserRepository
Database--->APRepository
Database--->NotificationsRepository
ChatRepository-->ChatService
ApplicationState(fa:fa-list Application State)--->App
GeoIP(fa:fa-globe GeoIP Lookup)--->App
Statistics(fa:fa-list Statistics)--->App
end
subgraph VideoStorageProviders[Video Storage Providers]
LocalStorage((fa:fa-hard-drive Local Storage))
S3Storage((fa:fa-hard-drive S3 Storage))
end
subgraph ActivityPub
ActivityPubInboundHandlers[fa:fa-hashtag Inbound]
ActivityPubOutboundHandlers[fa:fa-hashtag Outbound]
end
subgraph Authentication
IndieAuth[fa:fa-key IndieAuth]
FediAuth[fa:fa-key FediAuth]
end
subgraph Notifications
DiscordNotifier[fa:fa-comment Discord]
BrowserNotifier[fa:fa-browser Browser]
end
subgraph WebServer[Web Server]
ActivityPubHandlers[fa:fa-file ActivityPub Handlers]
subgraph WebAssets[Web Assets]
EmbeddedStaticFiles((fa:fa-file Embedded\nStatic Assets))
OnDiskStaticFiles((fa:fa-file On Disk\nStatic Assets))
WebApplication[fa:fa-file Web\nApplication]
PublicFiles[fa:fa-file Public\nDirectory]
end
subgraph HTTPHandlers[fa:fa-browser HTTP Handlers]
AdminAPIs[Admin APIs]
ThirdPartyAPIs[3rd Party APIs]
WebSocket[WebSocket]
subgraph ChatAPIs[Chat APIs]
ChatUserRegistration[Chat User Registration]
Emoji[Emojis]
subgraph ChatAuthAPIs[Chat Authentication]
FediAuth
IndieAuth
end
end
subgraph VideoAPIs[fa:fa-video Video APIs]
ViewerPing[Viewer Ping]
PlaybackMetrics[Playback health metrics]
end
ActivityPubHandlers
ApplicationConfig[Application Config]
ApplicationStatus[Application Status]
Directory[Directory API]
Followers[Followers]
end
end
subgraph Streamer
BroadcastingSoftware>fa:fa-video BroadcastingSoftware]
end
%% All the services and packages require access
%% to dependencies through a Application reference.
App-.->HTTPHandlers
App-.->VideoPipeline
App-.->ActivityPub
App-.->Authentication
App-.Stream went\nonline.->Notifications
App-.->DirectoryNotifier[Directory Notifier]
LocalStorage--HLS-->OnDiskStaticFiles
RTMPService>RTMP Ingest]--RTMP-->VideoTranscoder
VideoTranscoder--HLS-->VideoStorageProviders
%% Viewers
VideoPlayer-->VideoStorageProviders
WebBrowser-->WebAssets
%% Streamers
BroadcastingSoftware--RTMP-->RTMPService
%% Style the nodes
%% Define reusable styles for node types
classDef bigtext font-weight:bold,font-size:20px
classDef repository fill:#4F625B,color:#fff
classDef webservice fill:#6082B6,color:#fff
classDef rtmp fill:#608200, color:#fff
classDef inbound fill:#6544e9,stoke:#fff,color:#fff
classDef outboundservice fill:#2386e2,stroke:green,color:#fff
classDef storage fill:#42bea6,color:#fff
%% Assign styles to nodes
class App bigtext
class UserRepository repository
class ConfigRepository repository
class APRepository repository
class NotificationsRepository repository
class ChatRepository repository
class HTTPHandlers inbound
class ActivityPubInboundHandlers inbound
class InboundWebhooks inbound
class ActivityPubOutboundHandlers outboundservice
class DiscordNotifier outboundservice
class BrowserNotifier outboundservice
class OutboundWebhooks outboundservice
class DirectoryNotifier outboundservice
class BroadcastingSoftware rtmp
class RTMPService rtmp
class Database storage
class LocalStorage storage
class S3Storage storage
%% Customize the theme styles
%%{init: {'theme':'base', 'themeVariables': {'darkMode': true, 'lineColor': '#c3dafe', 'tertiaryTextColor': 'white', 'clusterBkg': '#2d3748', 'primaryTextColor': '#39373d', "edgeLabelBackground": "white", "fontFamily": "monospace"}}}%%