Architecture

Rheomesh Architecture

Rheomesh is a Selective Forwarding Unit (SFU) implementation that provides efficient real-time media streaming capabilities. This document outlines the core architectural components and data flow within the system.

Overview

Rheomesh follows a typical SFU architecture pattern where the server acts as a central media router that selectively forwards media streams between connected clients without transcoding the media content.

Core Components

SFU Server

The SFU server is the central component that handles all media routing operations:

• Worker: The top-level container that manages system resources. Create one Worker per server process.
• Router: A media routing unit that handles multiple transports. Think of it as a “meeting room” where participants can exchange media. Multiple routers can be created to distribute load across different media sessions
• Transport: Individual connections for publishing or subscribing to media streams.

Transport Layer

The transport layer manages WebRTC connections between clients and the server:

• PublishTransport: Handles incoming media streams from clients who are publishing content (e.g., camera, microphone)
• SubscribeTransport: Manages outgoing media streams to clients who are consuming content
• RecordingTransport: Manages raw RTP transporting for recording.

Media Handling

• Publisher: Represents a media producer that receives and processes incoming media tracks from clients
• Subscriber: Represents a media consumer that sends media tracks to subscribing clients
• LocalTrack/RecordingTrack/RelayedTrack: Individual media streams (video or audio) that flow between clients

Data Flow

The media streaming process follows this sequence:

1. Publishing Phase:
   • Browser1 creates a VideoTrack and establishes a PublishTransport connection
   • The media is sent via RTP protocol to the SFU’s PublishTransport
   • The Publisher component processes and makes the track available for distribution
2. Routing Phase:
   • The Router manages track distribution between Publishers and Subscribers
3. Subscription Phase:
   • Browser2 establishes a SubscribeTransport connection
   • The Subscriber component receives the track from the Publisher
   • Media is forwarded via RTP to the subscribing client’s VideoTrack

Architecture Diagram

graph LR
subgraph SFU
    W[Worker] --> R1[Router]
    W --> R2[Router]
    subgraph R1[Router]
        PS1[PublishTransport]
        P1[Publisher]
        PS1 --> P1
        SS2[SubscribeTransport]
        S1[Subscriber]
        SS2 --> S1
        P1 -->|Track| S1
    end
end
subgraph Browser1
    PC1[PublishTransport]
    T1[VideoTrack]
    T1 --> PC1
end
subgraph Browser2
    SC2[SubscribeTransport]
    T2[VideoTrack]
    SC2 --> T2
end
PC1 -->|RTP| PS1
SS2 -->|RTP| SC2