Plaza MQTT

Plaza MQTT is the public square of the network, providing best-effort broadcast for presence, heartbeats, and real-time social events.

1. Purpose

• Low-latency discovery via hey_there.
• Periodic status heartbeats (Newspapers).
• Real-time social signaling (teasing, buzz).
• Coordination for Checkpoint consensus.

2. Conceptual Model

• Pub/Sub: Standard MQTT (default tls://mqtt.nara.network:8883).
• Best-Effort: QoS 0 only; no delivery guarantees.
• Coordination: Used for jittered responses (e.g., howdy) to avoid thundering herds.

Invariants

• Signed Payloads: Every message must be signed with the sender’s soul.
• Jittered Join: 0-5s delay before initial hey_there.
• Hybrid-Resilient: Falls back to Mesh HTTP gossip if MQTT is down.

3. Interfaces

Topic Reference

Topic	Purpose	Payload
nara/plaza/hey_there	Join announcement	SyncEvent(hey-there)
nara/plaza/chau	Graceful departure	SyncEvent(chau)
nara/plaza/howdy	Discovery response	HowdyEvent
nara/plaza/social	Social interactions	SyncEvent(social)
nara/newspaper/{name}	Status heartbeat	NewspaperEvent
nara/checkpoint/*	Checkpoint consensus	Proposal, Vote, Final

Newspaper Heartbeats

Published every 10-300s (per Chattiness).

• Signature: Covers raw JSON of the Status field.
• Content: Identity, Personality, Observations, and Buzz.

4. Algorithms

Connection & Jitter

1. TLS Connect.
2. Jitter: rand(0..5)s.
3. Subscribe to nara/#.
4. Broadcast hey_there.

Reconnect Loop

Randomized backoff (5-35s) on connection loss.

5. Failure Modes

• Broker Outage: Loss of real-time heartbeats; fallback to Zines.
• Spoofing: Unprotected topics require mandatory signature verification by subscribers.
• Message Loss: State derivation must be resilient to dropped QoS 0 broadcasts.

6. Security

• Transport: TLS.
• Application: Ed25519 self-authentication.
• Anonymity: Identity tied to soul, not IP (from Nara perspective).

7. Test Oracle

• TestMQTT_ConnectJitter: Delay verification.
• TestMQTT_SignedSyncEvents: Subscriber verification check.
• TestMQTT_NewspaperSignature: Status payload integrity.
• TestMQTT_ReconnectLoop: Backoff behavior.