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🛰 NATS Visualizer

Four simulated microservices publish events over NATS. Watch Core pub/sub, JetStream persistence, and KV health heartbeats update in real time.

OpenSwoole-native NATS client — a thin coroutine-native TCP client replaces third-party NATS libraries that require incompatible event loops. The read loop runs in a dedicated coroutine and yields cooperatively on every recv().
Core pub/sub (best-effort) — Auth and Inventory subscribe via wildcard Core pub/sub (via.events.*). Fire-and-forget: if you kill one of these services its simulator stops and any events published while it is offline are gone forever.
Guaranteed delivery (JetStream durable consumers) — Orders and Payments subscribe via named durable push consumers with explicit ACK. Kill = pause the consumer: the simulator keeps publishing, JetStream buffers un-ACKed messages. Revive = re-subscribe: the burst of missed events arrives immediately.
JetStream persistence — the VIAEVENTS stream captures every message in memory. The durable consumer tracks its last-delivered sequence across subscribe/unsubscribe cycles — a revived subscriber never misses a message.
KV health heartbeats — each service publishes a heartbeat to $KV.viahealth.{service} every 2 s. Guaranteed services always heartbeat (only the consumer is paused); best-effort services stop heartbeating when killed. The health grid reads KV age.
Lazy init — the NATS connection is established on the first page load inside the HTTP coroutine, where coroutine APIs are always safe. A double-init guard (flag set before Coroutine::create()) prevents race conditions.
NATS Connecting… 0 events logged
Services
📦
Orders 🔒
— waiting —
0 events
💳
Payments 🔒
— waiting —
0 events
🔐
Auth 📡
— waiting —
0 events
📊
Inventory 📡
— waiting —
0 events
NATS
Core via.events.* auth, inventory
JetStream VIAEVENTS 0 msgs
Durable ui-orders, ui-payments ACK guaranteed
KV viahealth heartbeats
Audit via.events.* 0 ✓
Health (KV age)
📦 Orders —
📦 DOWN
💳 Payments —
💳 DOWN
🔐 Auth —
🔐 DOWN
📊 Inventory —
📊 DOWN
Event Stream
Waiting for events…
Source Example handler .php → NatsClient .php → Template .twig →

🎯 Actions

kill-orders / kill-payments

Pauses the JetStream durable consumer (unsubscribes from the deliver inbox). Simulator keeps publishing; NATS buffers un-ACKed messages. Health tile stays green — the service is still alive, only the consumer is paused.

kill-auth / kill-inventory

Stops the event simulator entirely. Events are silently dropped — Core pub/sub has no persistence. Health tile flips to DOWN after 8 s of silence.

revive-{service} (×4)

Guaranteed services: re-subscribes to the deliver inbox; JetStream immediately delivers all buffered events in a burst. Best-effort: restarts the simulator and publishes a fresh KV heartbeat.

👁 Views

mission_control.html.twig

Flow diagram piping services → NATS → browser, service kill/revive cards with delivery-type badges, NATS topology with health tiles, and a live event stream.