HLD-321·Coordination & IDs
Hard · 1,500 ptsGlobal Video Conferencing Room Signaling & SFU Topology
Design Zoom / Google Meet’s room signaling, participant roster state, and regional Selective Forwarding Unit (SFU) relay allocation at 9:00 AM join storms.
Max p99
≤ 50 ms
Availability
≥ 99.5%
Budget
≤ $8,300
Functional Requirements
- FR-1POST /meetings/{meeting_id}/join — Allocates optimal regional SFU node and updates participant roster.
- FR-2GET /meetings/{meeting_id}/roster — Serves active speaker, mute/video flags, and cascaded SFU endpoints.
- FR-3PATCH & DELETE /meetings/{meeting_id}/join — Updates, cancels, or deletes meeting_id records and immediately invalidates or updates cached state (read-after-write).
- FR-4Must guarantee read-after-write participant state and survive signaling shard failover.
Workload Profile
Mid-Hour Calls42,000 Roster Read RPS / 8,500 Join/Mute Write RPS
9:00 AM Global Join Storm120,000 Read RPS / 26,000 Join Write RPS
Active Working Set24 GB live meeting room rosters & SFU capacity maps
Traffic DistributionSynchronized top-of-hour burst + 10k-attendee townhall meeting_id skew
Consistency Model
Read-after-write on room admission, host mute-all controls, and SFU cascade assignments.
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