REMOTE LEARNING PLATFORM

1// SFU topology: one publisher → many subscribers via media server
2export class SFUSignalingService {
3  constructor(
4    private io: Server,
5    private redis: Redis
6  ) {
7    this.io.adapter(createAdapter(redis, redis.duplicate()));
8  }
9
10  async publishStream(roomId: string, offer: RTCSessionDescription) {
11    const room = await this.getOrCreateRoom(roomId);
12
13    // Publisher sends one stream; SFU fans it out to all subscribers
14    // This removes the N² WebRTC connection problem from mesh topology
15    room.publisherOffer = offer;
16    await this.redis.hset(`room:${roomId}`, "offer", JSON.stringify(offer));
17
18    // Notify all waiting subscribers in this room (cross-server via Redis)
19    this.io.to(roomId).emit("publisher:ready", { roomId });
20  }
21}